Community RSS Feed
http://community.wolfram.com
RSS Feed for Wolfram Community showing any discussions in tag Wolfram Scienceattachment.php?postid=632 sorted by activeCan not make a proper Classic Klein Bottle in version 11.20 of Mathematica.
http://community.wolfram.com/groups/-/m/t/1224031
Everything works fine in version 10, but in Version 11.20 there is a slice taken out of the Klein Bottle image...It does this no matter what version of the code I use in Version 11.2. It also does it while making a stylized Klein Bottle described here... http://members.wolfram.com/jeffb/visualization/klein.shtml Here is an example of code that makes a faulty output...Can someone come up with code that makes a proper Klein Bottle without a slice taken out out it in Version 11.20?
klein[u_, v_] := Module[{
bx = 6 Cos[u] (1 + Sin[u]),
by = 16 Sin[u],
rad = 4 (1 - Cos[u]/2),
X, Y, Z},
X = If[Pi < u <= 2 Pi, bx + rad Cos[v + Pi], bx + rad Cos[u] Cos[v]];
Y = If[Pi < u <= 2 Pi, by, by + rad Sin[u] Cos[v]];
Z = rad Sin[v];
{X, Y, Z}
]
ParametricPlot3D[klein[u, v], {u, 0, 2 Pi}, {v, 0, 2 Pi},
Axes -> False, Boxed -> False, ViewPoint -> {1.4, -2.6, -1.7}]Roy Scott2017-11-18T01:58:23ZGet FinancialData price history?
http://community.wolfram.com/groups/-/m/t/1097940
Since 16 may 2017, why am I not able to get the price history of US stock market tickers? Please see output below! Has anything changed?
In[9]:= FinancialData["GE", {{2017, 1, 3}, {2017, 5, 15}}]
Out[9]= Missing["NotAvailable"]
In[10]:= FinancialData["IBM", {{2017, 1, 3}, {2017, 5, 15}}]
Out[10]= Missing["NotAvailable"]sridev ramaswamy2017-05-18T12:09:48ZMachine Learning With Weighted Data
http://community.wolfram.com/groups/-/m/t/1223968
It does not appear easy within the current Classify, Predict or NetTrain functions to accommodate weighted data. It I am wrong about this, can anyone tell me how to do so. If anyone has a work around, could you please make a suggestion.
Motivation: I have several projects that would benefit from weighted data, the latest being to explain this really interesting paper using Mathematica: [https://arxiv.org/pdf/1602.04938.pdf][1] . The idea would basically be to emulate one machine learning method -- the complex one such as a neural net -- with a less opaque one (such as a decision tree) but with the emulator only being responsible for producing similar answers within a neighborhood of certain points. This way one could use something close to human language to explain what a more complex and more opaque classifier was doing.
I'm attaching a draft notebook that shows some preliminary work in this field and indicates where having a weighted classifier would be an improvement.
[1]: https://arxiv.org/pdf/1602.04938.pdfSeth Chandler2017-11-17T22:10:07ZFinding yoga-poses constellations in the night sky
http://community.wolfram.com/groups/-/m/t/1207400
![found constellations][9]
## Story Time ##
At its first meeting in 1922, the International Astronomical Union (IAU), officially adopted the list of 88 constellations that we use today.
These include 14 men and women, 9 birds, two insects, 19 land animals, 10 water creatures, two centaurs, one head of hair, a serpent, a dragon, a flying horse, a river and 29 inanimate objects. As many of us have (frustratingly) witnessed first hand while star-gazing - most of these bear little resemblance to their supposed figures. Instead, it is more likely that the ancient constellation-makers meant them to be symbolic, a kind of celestial "Hall of Fame" for their favorite animals or heroes.
This begs two questions I sought to answer with this project:
1. Can we 'do better' now with the WL's StarData[] curated data and Machine Learning functionality?
2. What if the ancient constellation-makers were slightly more creative? Say they looked up at the sky, and only saw yoga-poses!
Some examples of the found yoga-pose constellations, projected on images of the night sky are shown here, with a walk-through of the code below:
[![example yoga-pose constellations][1]][2]
## Yoga Poses ##
First things first, finding images for yoga poses.
Turns out, the WL has a built in YogaPose Entity Class with 216(!) available entities and their schematics.
A lot of these are very similar (e.g. palms facing up/down) and we therefore only select a subset of them, which differ substantially from each other:
yogaposes = EntityClass["YogaPose", All] // EntityList;
chosenPoses =
List /@ {4, 6, 7, 8, 11, 14, 23, 25, 28, 35, 38, 43, 51, 54, 56, 59,
63, 65, 71, 72, 76, 77, 78, 84, 88, 90, 98, 100, 102, 103, 110,
111, 112, 113, 116, 118, 119, 125, 126, 133, 139, 142, 149, 152,
153, 154, 155, 156, 160, 164, 165, 167, 172, 177, 178, 180, 182,
183, 184, 190, 193, 194, 195, 197, 202, 204, 206, 207, 209, 210,
212, 215, 216};
Shallow[Extract[yogaposes, chosenPoses]]
We write a wrapper to ensure the schematics are padded to give a square image and visualize our 73 constellations:
makeSquare[gr_, size_, bool_: False] :=
Block[{range, magnitudes, order, padding, newRanges, res},
range = AbsoluteOptions[gr, PlotRange][[1, 2]];
magnitudes = Abs[Subtract @@@ range];
order = Ordering[magnitudes, 2, Greater];
padding = Subtract @@ magnitudes[[order]]/2;
newRanges = {{-1, 1} padding + Last[range[[order]]],
First[range[[order]]]};
res = Show[gr, PlotRange -> Reverse@newRanges[[order]],
ImageSize -> size];
If[bool, Rasterize[res], res]]
Multicolumn[
makeSquare[#["SimplifiedSchematic"], 64] & /@
Most[Extract[yogaposes, chosenPoses]], 9, Frame -> All]
![constellations graphic][3]
## Neural Network ##
Our problem now can be worded as a classification one: *given 5-10 stars, classify them as one of the 73 yoga-poses constellations*
The problem with that formulation of-course is that 5-10 randomly selected points inside the constellation region isn't specific enough to differentiate between constellations. The image below shows that although 1000 sets of 10 points will define the shape, 10 points alone fall short:
![pointsInMesh][4]
Instead, we compute the Voronoi diagram of the points, using DistanceTransform to leverage already-optimized convolutional neural nets used for classifying images. Note that, even if (naturally) the results are less clear with fewer points (left to right) - the result with only 10 points at the far right is still quite recognizable to a human eye:
![distanceTransforms][5]
With this in-mind, we create a neural network similar to the [VGG16][6] neural network, with successive 5x5 convolutions, ReLu activation functions and Max pooling layers. Finally note that we use an average pooling instead of fully connected layers to reduce the number of parameters and the use of dropout layers.
conv[output_] := ConvolutionLayer[output, {5, 5}, "PaddingSize" -> 2]
pool[size_] := PoolingLayer[{size, size}, "Stride" -> size]
lenet = NetChain[
{conv[32], Ramp, conv[32], Ramp, pool[2], conv[64], Ramp, conv[64],
Ramp, pool[2], conv[128], Ramp, conv[128], Ramp, conv[128], Ramp,
PoolingLayer[{9, 9}, "Stride" -> 9, "Function" -> Mean],
FlattenLayer[], DropoutLayer[], 73, SoftmaxLayer[]},
"Output" -> NetDecoder[{"Class", Extract[yogaposes, chosenPoses]}],
"Input" -> NetEncoder[{"Image", {64, 64}, ColorSpace -> "Grayscale"}]
]
The training set then consists of generating 10-15 points inside the constellation region (resized and padded to allow for rotations later), and taking their DistanceTransform:
meshes[n_] :=
meshes[n] =
ImagePad[ColorNegate@
makeSquare[
yogaposes[[chosenPoses[[n, 1]]]]["SimplifiedSchematic"], 44], 10]
trainingSet[n_, m_, iter_] :=
With[{reg =
ImageMesh[meshes[n], CornerNeighbors -> False,
Method -> "MarchingSquares"]},
Thread[ColorConvert[
ImageAdjust[
DistanceTransform[Image[SparseArray[# -> 0, {64, 64}, 1]]]],
"Grayscale"] & /@
Clip[Round@RandomPoint[reg, {iter, m}], {1, 64}] ->
yogaposes[[chosenPoses[[n, 1]]]]]]
exampleTrainingSet =
Flatten[trainingSet[#, 10, 1] & /@ RandomInteger[{1, 73}, 10], 1]
The net took a couple of hours to train on ~100,000 examples on my CPU.
Here we import the trained net:
lenetTrained = Import["constellationsNet.wlnet"]
## Night Sky ##
We're almost ready to classify the night sky. We first need the location of the 10,000 brightest stars along with their Right Ascension and Declination:
brightest =
StarData[EntityClass[
"Star", {EntityProperty["Star", "ApparentMagnitude"] ->
TakeSmallest[10000]}], {"RightAscension", "Declination",
"ApparentMagnitude"}]
We can plot these on the night sky using no projection (i.e. RA Vs Dec), using the sinusoidal projection (taken by Kuba's excellent [answer][7] in SE) or on the celestial sphere given by the following transformations respectively:
$$sinusoidal:\{(\alpha -\pi ) \cos (\delta
),\delta \}$$
$$map to3D:\{\cos (\alpha ) \cos (\delta ),\sin
(\alpha ) \cos (\delta ),\sin (\delta
)\}$$
![brightestStarsProjections][8]
## Classification ##
Finally, we use these 10,000 brightest stars to compute a multivariate smooth kernel distribution out of which to sample from and a Nearest function to compute neighboring stars. We need to of-course use our own distance function on the celestial sphere:
wrap[list_] := Block[{xs, ys},
{xs, ys} = Transpose[list];
Thread[{Mod[xs, 2 \[Pi]], Mod[ys, \[Pi], -\[Pi]/2]}]]
mapTo3D[\[Alpha]_, \[Delta]_] = {Cos[\[Alpha]] Cos[\[Delta]],
Cos[\[Delta]] Sin[\[Alpha]], Sin[\[Delta]]};
dist[{u_, v_}, {x_,
y_}] := (#1[[1]] - #2[[1]])^2 + (#1[[2]] - #2[[2]])^2 + (#1[[
3]] - #2[[3]])^2 & @@ mapTo3D @@@ {{u, v}, {x, y}}
pts = wrap@QuantityMagnitude[UnitConvert[brightest[[6 ;;, ;; 2]]]];
nf = Nearest[pts, DistanceFunction -> dist]
sm = SmoothKernelDistribution[pts]
Our search algorithm is therefore defined as follows:
1. Pick a random position from the night sky distribution
2. Compute its 5-10 nearest neighbors
3. Classify those stars and their rotations by $\frac{2 \pi }{15}$
4. Select the rotation which gives the highest accuracy
5. Associate constellation to running association and repeat
rescale[list_] := Block[{xs, ys},
{xs, ys} = Thread[list];
Thread[Rescale[#, MinMax[#], {11, 54}] & /@ {xs, ys}]]
rotate[\[Alpha]_, pts_] :=
ImageAdjust@
DistanceTransform[
Image@SparseArray[
Round@RotationTransform[\[Alpha] , {65/2, 65/2}][rescale[pts]] ->
0, {64, 64}, 1]]
sky = <||>;
accumulate[] :=
Block[{pts =
nf[Mod[RandomVariate[sm] + {0, \[Pi]}, 2 \[Pi]] - {0, \[Pi]},
RandomInteger[{5, 10}]], \[Alpha], pred},
{\[Alpha], pred} =
Last[SortBy[
First /@
Table[Thread[{\[Alpha],
lenetTrained[rotate[\[Alpha], pts],
"TopProbabilities"]}], {\[Alpha], 0, 2 \[Pi], (2 \[Pi])/
15}], Last]];
If[Not[KeyExistsQ[sky, pred[[1]]]] ||
TrueQ[sky[pred[[1]], "Accuracy"] < pred[[2]]],
AssociateTo[sky,
pred[[1]] -> <|"Accuracy" -> pred[[2]],
"Image" ->
HighlightImage[
makeSquare[pred[[1]]["SimplifiedSchematic"],
64], {PointSize[Medium], Red,
Round[RotationTransform[\[Alpha], 65/2 {1, 1}][rescale@pts],
0.5]}], "Points" -> pts, "Angle" -> \[Alpha]|>], Nothing];]
We can import a precomputed association with 20 such constellations:
selectedAsc = Import["skyAsc.m.gz"]
## Results ##
Finally, we orient the schematic based on the optimally found angle and (manually) connect the dots.
orient[pts_, \[Alpha]_] :=
Round[RotationTransform[\[Alpha], 65/2 {1, 1}][rescale@pts], 0.5]
lines = {{{10, 7, 3, 1, 4, 9, 2, 5, 8}, {2, 6}}, {{7, 3, 1, 9,
6}, {10, 2, 1, 8}, {4, 3, 5}}, {{7, 8, 9, 4, 3, 2, 10}, {1, 2, 6,
5}}, {{10, 2, 1, 3, 9, 5}, {7, 1, 4, 6, 8}}, {{5, 4, 1, 2,
3}}, {{10, 4, 5, 7, 9, 3, 8}, {6, 1, 2, 3}}, {{9, 5, 6, 3, 1, 2,
7}, {7, 4, 8}}, {{7, 6, 2, 3, 5, 8}, {9, 5, 4}, {3, 1}}, {{6, 2,
1, 3, 4}, {2, 5}}, {{5, 6, 4, 1, 2, 8, 3, 7}}, {{10, 6, 3, 2,
7}, {5, 2, 1, 4, 9, 8}}, {{9, 5, 1, 2, 4, 8, 7}, {6, 3, 8}}, {{6,
10, 4, 2, 1, 3, 9, 7, 5, 8}}, {{6, 7, 3, 2, 1, 4, 5}}, {{10, 8,
3, 6, 7, 2, 5, 9}, {5, 1, 4, 3}}, {{6, 5, 2, 1, 3}, {1, 4}}, {{5,
1, 2, 3}, {1, 4}}, {{6, 3, 2, 1, 4}, {3, 5}, {2, 7}}, {{3, 6, 8,
2, 4, 5, 1, 7}}, {{3, 1, 2, 6, 5}}};
makeSquareAndScale[gr_, \[Alpha]_, size_, opacity_] :=
Block[{range, magnitudes, order, padding, newRanges, s},
range = AbsoluteOptions[gr, PlotRange][[1, 2]];
magnitudes = Abs[Subtract @@@ range];
order = Ordering[magnitudes, 2, Greater];
padding = Subtract @@ magnitudes[[order]]/2;
s = size/First[magnitudes[[order]]];
newRanges = {{-1, 1} padding + Last[range[[order]]],
First[range[[order]]]};
Graphics[{Opacity[opacity],
GeometricTransformation[
GeometricTransformation[
gr[[1]], {ScalingMatrix[{s,
s}], -1 First /@ (s Reverse@newRanges[[order]])}],
RotationTransform[\[Alpha], (size + 1)/2 {1, 1}]]},
ImageSize -> size]]
With[{l = Map[Line, lines, {2}]},
Multicolumn[
Table[Show[
makeSquareAndScale[
Keys[selectedAsc][[i]][
"SimplifiedSchematic"], -selectedAsc[[i, -1]], 64, 0.25],
Graphics[
GraphicsComplex[
rescale[selectedAsc[[i, -2]]], {l[[i]], Red, PointSize[Large],
Point /@ Sort /@ Flatten /@ lines[[i]]}]],
ImageSize -> 150], {i, 20}], 5, Frame -> All,
Appearance -> "Horizontal"]]
![found constellations][9]
These can also be superimposed on the full night-sky:
Graphics[{With[{l = Map[Line, lines, {2}]},
Table[GraphicsComplex[
selectedAsc[[i, -2]], {Orange, Thickness[Large], l[[i]], Red,
PointSize[Medium], Point /@ Sort /@ Flatten /@ lines[[i]]}], {i,
20}]], Opacity[0.25], PointSize[Small],
Point[Complement[pts, Flatten[Values@selectedAsc[[All, -2]], 1]]]},
ImageSize -> 750]
![found overlay][10]
sinusoidal[\[Alpha]_, \[Delta]_] = {(\[Alpha] - \[Pi]) Cos[\[Delta]], \
\[Delta]}
Graphics[{With[{l = Map[Line, lines, {2}]},
Table[GraphicsComplex[
sinusoidal @@@ selectedAsc[[i, -2]], {Orange, Thickness[Large],
l[[i]], Red, PointSize[Medium],
Point /@ Sort /@ Flatten /@ lines[[i]]}], {i, 20}]],
Opacity[0.25], PointSize[Small],
Point[sinusoidal @@@
Complement[pts, Flatten[Values@selectedAsc[[All, -2]], 1]]]},
ImageSize -> 750]
![found sinusoidal][11]
It is then a matter of Overlaying these found constellations to existing images of night skies to produce the images at the beginning of the post:
overlay[{img_, constellation_}, {size_, loc_, opac_}] :=
ImageCompose[imgs[[img]],
ImageResize[
Show[makeSquareAndScale[
Keys[selectedAsc][[constellation]][
"SimplifiedSchematic"], -selectedAsc[[constellation, -1]], 64,
opac], Graphics[
GraphicsComplex[
rescale[selectedAsc[[constellation, -2]]], {White,
Thickness[0.0075], Line /@ lines[[constellation]], White,
PointSize[.025],
Point /@ Sort /@ Flatten /@ lines[[constellation]]}]],
ImageSize -> 1000], size], Scaled[loc]]
## Conclusions / Lessons Learned ##
- It IS possible to find collections of stars in the night sky matching all sorts of shapes. Other built-in entities to try are Pokemons, Dinosaurs etc
- Not all the found constellation work 'perfectly'
- Machine Learning is a powerful tool, and the WL implementation makes it easy to get started
- Reformulating the problem to an easier, already solved problem (e.g. points -> 2D image input) can help Classification Accuracy
- Perhaps the most interesting aspect of neural networks now, is diversifying its applications - so be creative
This work was presented at the 2017 WTC (as part of a larger talk entitled "(De)Generative Art"). <br>
I look forward to any comments/suggestions.
<br>
<br>George
<br>
<br> PS The editor doesn't seem to let me attach the .wlnet and .m.gz files.
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=exampleImages.png&userId=11733
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=exampleImages.png&userId=616023
[3]: http://community.wolfram.com//c/portal/getImageAttachment?filename=4214constellationsGraphic.png&userId=616023
[4]: http://community.wolfram.com//c/portal/getImageAttachment?filename=randomPointsInmesh.png&userId=616023
[5]: http://community.wolfram.com//c/portal/getImageAttachment?filename=distanceTransforms.png&userId=616023
[6]: https://arxiv.org/pdf/1409.1556v6.pdf
[7]: https://mathematica.stackexchange.com/questions/89668/geoprojection-for-astronomical-data-wrong-ticks/89792#89792
[8]: http://community.wolfram.com//c/portal/getImageAttachment?filename=maps.png&userId=616023
[9]: http://community.wolfram.com//c/portal/getImageAttachment?filename=foundConstellations.png&userId=616023
[10]: http://community.wolfram.com//c/portal/getImageAttachment?filename=overlaidConstellations.png&userId=616023
[11]: http://community.wolfram.com//c/portal/getImageAttachment?filename=overlaidConstellationsSinusoidal.png&userId=616023George Varnavides2017-10-24T04:17:44ZCould not read result file, missing data matrix, the file might be courupt
http://community.wolfram.com/groups/-/m/t/1223831
I'm trying to run a Modelica code in SystemModeler:
model code
//constants
constant Real pi = 2 * Modelica.Math.asin(1.0);
parameter Real mukpc = 0.2;
parameter Real muspc = 0.0;
parameter Real mukps = 0.0;
parameter Real musps = 0.0;
parameter Real mukcs = 0.2;
parameter Real muscs = 0.0;
parameter Real mp = 1.0;
parameter Real js = 2.0;
parameter Real b1 = 0.01;
parameter Real b2 = 0.01;
parameter Real b3 = 0.015;
parameter Real r1 = 0.01;
parameter Real r2 = 0.003;
parameter Real r3 = 0.003;
parameter Real Ts = 1;
parameter Real Tw = 0.9;
parameter Real absTol = 0.01;
//variables
Real X1, X2, X3, Y1, Y2, Y3, tets, V1, V2, V3, omgs, A1, A2, A3, alps, Fp1, Fp2, Fp3, Fncp1, Fncp2, Fncp3, Ffcp1, Ffcp2, Ffcp3, Tcp1, Tcp2, Tcp3, Ffsp1, Ffsp2, Ffsp3, Fnsp1, Fnsp2, Fnsp3, Tfsp1, Tfsp2, Tfsp3, Text, Tfsc, Fscx, Fscy, T1, T2, T3;
initial equation
tets = pi / 3;
omgs = 0.1;
equation
//inpute forces
Fp1 = if mod(time, 3 * Ts) < Tw then 1000 else 0;
Fp2 = if mod(time, 3 * Ts) < Tw + Ts and mod(time, 3 * Ts) > Ts then 1000 else 0;
Fp3 = if mod(time, 3 * Ts) < Tw + 2 * Ts and mod(time, 3 * Ts) > 2 * Ts then 1000 else 0;
Text = 0;
//derivatives
V1 = der(X1);
V2 = der(X2);
V3 = der(X3);
A1 = der(V1);
A2 = der(V2);
A3 = der(V3);
omgs = der(tets);
alps = der(omgs);
//kinematics
X1 = r1 * cos(tets) + r2;
Y1 = r1 * sin(tets);
X2 = r1 * cos(tets + 2 * pi / 3) + r2;
Y2 = r1 * sin(tets + 2 * pi / 3);
X3 = r1 * cos(tets + 4 * pi / 3) + r2;
Y3 = r1 * sin(tets + 4 * pi / 3);
//dynamic equations
//shaft
js * alps = T1 + T2 + T3 - Text - Tfsc;
Fscx = Fnsp1 + Fnsp2 + Fnsp3;
Fscy = Ffsp1 + Ffsp2 + Ffsp3;
//Fsc =sqrt(Fscx^2+Fscx^2);
T1 = Fnsp1 * Y1 - Ffsp1 * X1 - Tfsp1;
T2 = Fnsp1 * Y2 - Ffsp2 * X2 - Tfsp2;
T3 = Fnsp3 * Y3 - Ffsp3 * X3 - Tfsp3;
//p1
mp * A1 = Fp1 - Ffcp1 - Fnsp1;
Ffsp1 = Fncp1;
Tfsp1 + Fnsp1 * (b2 / 2 - Y1) = Ffsp1 * b1 - Fp1 * b2 / 2 + Tcp1;
//p2
mp * A2 = Fp2 - Ffcp2 - Fnsp2;
Ffsp2 = Fncp2;
Tfsp2 + Fnsp2 * (b2 / 2 - Y2) = Ffsp2 * b1 - Fp2 * b2 / 2 + Tcp2;
//p3
mp * A3 = Fp3 - Ffcp3 - Fnsp3;
Ffsp3 = Fncp3;
Tfsp3 + Fnsp3 * (b2 / 2 - Y3) = Ffsp3 * b1 - Fp3 * b2 / 2 + Tcp3;
//friction
Ffcp1 = -mukpc * (abs(Fncp1) + abs(Tcp1 / b3)) * sign(V1);
Ffcp2 = -mukpc * (abs(Fncp2) + abs(Tcp2 / b3)) * sign(V2);
Ffcp3 = -mukpc * (abs(Fncp3) + abs(Tcp3 / b3)) * sign(V3);
Tfsp1 = 0;
Tfsp2 = 0;
Tfsp3 = 0;
Ffsp1 = 0;
Ffsp2 = 0;
Ffsp3 = 0;
Tfsc = mukcs * sqrt(Fscx ^ 2 + Fscy ^ 2) * sign(omgs);
end code;
But I get the error:
> Error
> Simulation of foo exited with an error(-1073741819), see log window for details
![enter image description here][2]
and then:
> Error: Could not read result file "C:/Users/foo/AppData/Local/Temp/WolframSystemModeler-5.0.0/sme.5.0.0_1510933977_23281.mat". Missing data_2 matrix, the file might be corrupt.
![enter image description here][3]
**I would appreciate if you could help me understand what is the problem and how can I solve it?**
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=5892Untitled.png&userId=1014408
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=4053Untitled.png&userId=1014408
[3]: http://community.wolfram.com//c/portal/getImageAttachment?filename=10469Untitled.png2.png&userId=1014408Foad Sojoodi Farimani2017-11-17T16:05:50ZCan this expression be written in closed form?
http://community.wolfram.com/groups/-/m/t/1222861
Observe the following Wolfram Mathematica expression which results in a table of integer sequences:
b[n_, k_] := b[n, k] = If[n == 0, 1, If[n == 1, If[k > 0, 1, 0], Sum[Binomial[n-1, r-1]*b[r-1, k-1]*b[n-r, k-1], {r, 1, n}] ] ]; t [n_, k_] := b[n, k] - If[k > 0, b[n, k-1], 0]; Table[Table[t[n, k], {k, 0, n}], {n, 0, 10}]
I'm struggling to interpret what this is actually doing. Clearly it's quite a complicated mess of if statements, but I'm not entirely sure if they are necessary or not. I obtained the expression from here:
https://oeis.org/A195581
Because I wanted to determine an expression (dependent on the two variables n and k) which would result in table of integers seen there. Would somebody please write the Mathematica code above in closed form so that it's easier to understand? If this is not possible, can you at least try to explain what's going on, and perhaps give an expression which models the above in *most* situations?John Travolski2017-11-16T03:22:25ZCorrection to Documentation for Cepstrogram & Cepstrogram
http://community.wolfram.com/groups/-/m/t/1218929
Just as an FYI, the default partition size for these two routines is
2^(Round[Log[2,Length[list]]]+1)
rather than
2^Round[Log[2,Length[list]]]+1
as stated in the docs. The default step size is any number between `Round[partition/3]` and the length of the list.
Cheers, ScottScott Guthery2017-11-09T01:11:25ZMy Mathematica keeps asking for Activation Key on startup?
http://community.wolfram.com/groups/-/m/t/1222950
Hi all,
Upon startup, every now and then, my Mathematica program will ask for an activation key. **It is not expired.**I will go on the Wolfram User Portal to find my activation key, and I will enter it. It will not work. I will have to uninstall and redownload Mathematica.
Does anybody have any suggestions or know what may be causing this issue?
Best,
NNish Paul2017-11-16T01:31:52Z[✓] Pasting numerical expressions into Input Cells?
http://community.wolfram.com/groups/-/m/t/1220439
I would like to create a PasteButton that will paste the following expression into an existing Input Cell and display in the Input Cell with the 6 place precision while keeping the full underlying machine precision. From my efforts I suspect that this is not possible because the only way to obtain the shortened display is to paste an entire Output Cell..
expr = N[x/3 + 2 y/3]
giving
0.333333 x + 0.666667 y
The following is just the simplest approach, which does not work. I haven't found any other approach that works either.
PasteButton["1/3", expr]
The resulting button pastes the following where the shorter form would be preferable.
0.3333333333333333` x+0.6666666666666666` y
Does anyone know a way to specify a PasteButton that will paste the 6 place Output display into an Input Cell?David J M Park Jr2017-11-12T06:12:37ZSort a table with respect to other?
http://community.wolfram.com/groups/-/m/t/1221539
Hi,
I have two 36 X 3 tables. First columns in both of them are independent terms/numbers, while second and third columns have same indices (numbers) from 1 - 6, but in different orders. I want to arrange the rows of table B in the same order as in A, with respect to second and third elements of them.
For example if
A = {{X, 2, 1}, {Y, 2, 3}, {Z, 2, 4}...}
and
B = {{x, 2, 3}, {y, 2, 4}, {z, 2, 1}....}
I want B to be rearranged to
B_new = {{z, 2, 1}, {x, 2, 3}, {y, 2, 4}....}
Will be thankful for any suggestion. Attached is the *.nb file having these tables.S G2017-11-14T10:28:55ZTrace path of a point from a body using MultiBody library in SM
http://community.wolfram.com/groups/-/m/t/1222597
In many CAE software (SolidWorks, RecurDyn...) it is possible to trace the curve that a certain point follows during a simulation. This is useful to show the motion of the point and compare the results with the expected ones or even with the output of another software.
Is there a way to do this in SystemModeler? I am working with mutibody mechanical systems using the MultiBody library.
For example, in the following simulation:
![enter image description here][1]
The goal is to show the arc followed by the sphere during the simulation. The curve is to be drawn as the motion occurs and export the data to a plain text file (if possible).
Best regards,
William
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=SMMotion.gif&userId=1190887JOSE OLIVER2017-11-15T11:03:39ZDatabin not updated?
http://community.wolfram.com/groups/-/m/t/1222161
Hi, I recently started to use Data Drop to store sensor data for analysis and visualization,
Creating the bin was easy and my Python program on my Raspberry Pi writes data to it via the Web API.
When I refer to it in Mathematica on my Mac (as Databin["psyLf0X2"] ) it tells me it has 6 entries and every time I evaluate it again that does not change.
However when I look in My Databins it actually has 14 entries... Why is it not updated?
What am I missing?Ted vanderTogt2017-11-15T15:53:18ZThe voters have spoken - but what did they say? (Part 3)
http://community.wolfram.com/groups/-/m/t/1222959
Introduction
----------
Elections are fundamental to our democracies and way of life. The electorate bestows power on the lawmakers and public officials whose legitimisation is derived solely from the fact that they are elected. In recent times, many elections, such as the presidential elections the United States and the Brexit and general elections in the United Kingdom have seen a very pronounced polarisation the electorate. Can mathematics and the Wolfram Language help to better understand this crucial process of the most fundamental decision making process in societies? The main question I want to discuss in a sequence of posts is what can be learnt from elections. So this post is about computational politics.
It is important to notice that democracies rely on a general acceptance of the result of elections. Without that consensus a peaceful co-existence is at risk. Societies agree on certain electoral procedures and the results have to be understood to be final. There are, however, more fundamental questions such as how do we derive the "voters will" from ballots. That is a highly non-trivial problem. Also, elected politicians often claim that they represent the "will of the people". But is that true and what is the "will of the people"? Hence, my question: the voters have spoken - but what did they say?
This is the third of a series of posts:
1. [Electoral systems - interpreting the will of the voters][1]
2. Gerrymandering - shaping the voters' will to your liking
3. **Analysis of the Brexit vote - how do we know what did the voters really want?**
This part of the sequence of posts will analyse the results of the Brexit vote in the United Kingdom. The question asked was basically a yes/no question and with small majority the social choice was to conduct Brexit. The rules of this process have been followed and the decision is binding. There is, however, a related question: Did the outcome in this particular case actually give sufficient evidence that this is the "will of the people" as many politicians state. If we want to evaluate the power of evidence there are mathematically established procedures. Similar procedures are for example applied in medical trials to evaluate the evidence provided by data to support a particular hypothesis. We will apply this type of procedure to the Brexit elections.
All posts were developed with [Bjoern Schelter][2], who is also a member of this community. He is indeed the expert on these methods.
**Disclaimer:** this post might be modified slightly over the next couple of days.
Data download and preparation
----------
We will start by obtaining some of the data required for this post. The [central dataset is provided by the electoral commission][3]. It is attached to this post. We download and them import the data like so:
SetDirectory[NotebookDirectory[]]
votingData = Import["EU-referendum-result-data.csv"];
Here is a short extract of the data:
votingData[[1 ;; 5]] // Transpose // TableForm
![enter image description here][4]
Next, we will need some data on the local authorities/electoral districts from [here][5]. We then import:
localauthorities = Import["Local_Authority_Districts_December_2016_Generalised_Clipped_Boundaries_in_Great_Britain.shp"];
explanationShape = Import["Local_Authority_Districts_December_2016_Full_Clipped_Boundaries_in_Great_Britain.csv"];
These data sets contain information about the shape and location of the local authority boundaries and data on how to match that with the voting outcome in the first file. To get a first glance at the data we re-arrange and organise the data like so:
Monitor[areas =
Table[QuantityMagnitude[UnitConvert[If[Length[#] > 1, Total[GeoArea /@ #], GeoArea[#]]], "SI"] & @(localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]), {k, 1, Length[localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]]]}];, k]
and
translateshpvote = SortBy[(Flatten /@ Transpose[{SortBy[Transpose[{Range[380], areas}], Last], SortBy[explanationShape[[2 ;;]], #[[9]] &]}])[[All, {1, 4}]], First];
The first representation is not very telling. It shows the outcome of the election.
Graphics[Flatten[
Table[{ColorDataFunction["TemperatureMap", "Gradients", {0, 1}, Blend["TemperatureMap", #]& ][(Select[
votingData[[2 ;;]], #[[4]] == translateshpvote[[k, 2]] &][[1]])[[-3]]/100.], localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1, 380}],1], AspectRatio -> GoldenRatio]
![enter image description here][6]
The "blue-r" the colour the higher the percentage of leave votes. Yellow indicates a preference for remain. We will need to clean the data further and will then plot it with a threshold to see which regions decided for Leave and which ones for Remain:
substitute = ({#[[1]][[{1, 4}]] -> #[[2]][[{1, 4}]], #[[2]][[{1,
4}]] -> #[[1]][[{1, 4}]]} &@((Flatten /@
Transpose[{SortBy[Transpose[{Range[380], areas}], Last],
SortBy[explanationShape[[2 ;;]], #[[9]] &]}])[[205 ;; 206]]))
translateshpvoteclean = translateshpvote /. substitute;
Graphics[Flatten[
Table[{ColorDataFunction["TemperatureMap", "Gradients", {0, 1}, Blend["TemperatureMap", #]& ][
If[# > 0.5, 1, 0] & @((Select[Select[votingData[[2 ;;]], #[[1]] < 381 &], #[[4]] == translateshpvoteclean[[k, 2]] &][[1]])[[-3]]/100.)],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1, 380}],1], AspectRatio -> GoldenRatio]
![enter image description here][7]
The strong divide between England and Scotland becomes apparent from that figure. We will use the following style of the image in much of the remainder of the post:
Graphics[Flatten[
Table[{ColorData[
"RedGreenSplit"][((Select[
Select[votingData[[2 ;;]], #[[1]] < 381 &], #[[4]] ==
translateshpvoteclean[[k, 2]] &][[1]])[[-3]]/100.)],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1, 380}],
1], Background -> Black, AspectRatio -> GoldenRatio]
![enter image description here][8]
What does the Brexit election outcome tell us? What did voters want?
----------
UK wide the percentage of leave votes (with respect to all valid votes) is:
N[Total[votingData[[2 ;;, 13]]]/Total[votingData[[2 ;;, 11]]]]
51.89%. This is in percentage of all valid votes. The percentage of leave with respect to the entire electorate is:
N[Total[votingData[[2 ;;, 13]]]/Total[votingData[[2 ;;, 6]]]]
37.4%. This is the percentage of the entire electorate who voted for remain.
N[Total[votingData[[2 ;;, 12]]]/Total[votingData[[2 ;;, 6]]]]
34.7%. The percentage of non-voters is:
N[(Total[votingData[[2 ;;, 6]]] - Total[Flatten@votingData[[2 ;;, 12 ;; 13]]])/Total[votingData[[2 ;;, 6]]]]
27.8%. This means that we do not know the will of about 28% of all voters. Following the predefined social choice procedure, the vote was narrowly won by leave. That does not necessarily imply that this is "the will of the majority of people".
What would the result be with indirect representation?
----------
If we had a representational vote we would have to count the districts for remain and leave
{Count[#, "Remain"], Count[#, "Leave"]} &@((#1 > #2) & @@@ votingData[[2 ;;, {12, 13}]] //. {False -> "Leave", True -> "Remain"})
{119,263}. This result is even more extreme for leave. This is because the population in the local authorities is very different.
Histogram[votingData[[2 ;;, 6]], PlotRange -> All, PlotTheme -> "Marketing", ImageSize -> Large,
FrameLabel -> {"population", "number of authorities"}, LabelStyle -> Directive[Bold, 15]]
![enter image description here][9]
This shows that there are large fluctuations in the population of the areas. Let's represent that slightly differently. We first collect data about Leave votes, Electorate, Turnout and Electorate.
electionEUresolved =
Transpose@({#[[1]], #[[2]], #[[3]], #[[4]]} &@Transpose@((({#[[13]], #[[11]], #[[9]], #[[6]]} & /@ (Reverse@SortBy[votingData[[2 ;;]], #[[9]] &])))));
BubbleChart[{#[[3]], N@#[[1]]/#[[2]], #[[4]]} & /@ electionEUresolved,
BubbleSizes -> Small,
ChartLabels ->
Placed[(Reverse@SortBy[votingData[[2 ;;]], #[[9]] &])[[
All, {5, 3}]], Tooltip],
Epilog -> {Red, Line[{{50, 0.5}, {100, 0.5}}]},
PlotTheme -> "Marketing", BubbleScale -> "Area", ImageSize -> Large,
FrameLabel -> {"turnout", "percentage leave votes"},
LabelStyle -> Directive[Bold, 15]]
![enter image description here][10]
The bubble sizes (areas) correspond to the size of the electorate. Let's see whether there is a correlation with turnout:
lm = LinearModelFit[{#[[3]], N@#[[1]]/#[[2]]} & /@ electionEUresolved,x, x, Weights -> electionEUresolved[[All, 4]]]
![enter image description here][11]
The following table shows that the positive slope is highly significant.
lm["ParameterTable"]
![enter image description here][12]
We can add that to the figure:
Show[BubbleChart[{#[[3]], N@#[[1]]/#[[2]], #[[4]]} & /@
electionEUresolved, BubbleSizes -> Small,
ChartLabels ->
Placed[(Reverse@SortBy[votingData[[2 ;;]], #[[9]] &])[[
All, {5, 3}]], Tooltip],
Epilog -> {Red, Line[{{50, 0.5}, {100, 0.5}}]},
PlotTheme -> "Marketing", BubbleScale -> "Area", ImageSize -> Large,
FrameLabel -> {"turnout", "percentage leave votes"},
LabelStyle -> Directive[Bold, 15]],
Plot[lm[x], {x, 50, 85}, PlotStyle -> White]]
![enter image description here][13]
Seeing such a linear dependence, raises the natural question to which extent the result is biased by such correlations in the data. Linear Models are a powerful tool to account for various potential influencing factors on the final outcome of the election.
Linear Modelling
----------
Linear Models are a generalisation of linear regression; linear models allow us to model a Gaussian Distributed outcome by various inputs that may or may not be continuous. To demonstrate this we use the simple voting data; the dependent, outcome, variable is the percentage of people who voted to leave the EU.
percentleave = N[votingData[[2 ;;, 13]]/votingData[[2 ;;, 11]]];
collatedData = (Flatten /@
Transpose[{Table[
Select[votingData, explanationShape[[k, 2]] === #[[4]] &], {k,
2, Length[explanationShape[[1 ;;]]]}],
explanationShape[[2 ;;]]}]);
We can then prepare the data for the linear model:
inputLinearModel =
Flatten /@ Transpose[{# - Mean[#] &@ collatedData[[All, 9]], collatedData[[All, 3]], # - Mean[#] &@ (collatedData[[All, 6]]/collatedData[[All, 30]]),
N[collatedData[[All, 13]]/collatedData[[All, 11]]]}];
The steps above generate the table that defines the input into the linear model. All continuous input variables have been centralised such that their mean is zero. This is not needed but simplifies the interpretability of the results. This input variables to the linear model are turnout, i.e., the fraction of people who voted in the given local administrative area, region, i.e., the rough geographical region (non continuous, nominal variable), and a proxy for the population density.
lmodel = LinearModelFit[inputLinearModel, {turnout, region, popdensity}, {turnout, region, popdensity}, NominalVariables -> region];
lmodel["ParameterTable"]
![enter image description here][14]
The model output shows the estimates with respect to the intercept (1) in the table. The missing region is Yorkshire and The Humber such that Mathematica relates all results to this region. Note, that the estimate of 0.548879 means that Yorkshire and The Humber would have voted to leave the EU with 54.89%; this is the model output and does not necessarily match the actual result of the election. Since all continuous variables are mean zero, these 54.89% would be the result for Yorkshire and The Humber under the assumption that the have a typical UK average population density and turnout. The model can obviously be used to approximate the result for Yorkshire and The Humber better by evaluating the function with the correct values for the area. All other influencing factors are estimated with respect to this result. In other words to obtain the result for Scotland, the Scotland result would need to be added to the Yorkshire and The Humber result; so the best model guess for Scotland if otherwise indistinguishable from the while UK would have been -23.93%+54.89%=30.96%. This obviously deviates from the actual result for Scotland, which is likely caused by the other covariates, the turnout and population density in Scotland are different from the average UK value.
Next we want to analyse the same model but with data for Gibraltar and Ni added. We first need the respective areas of the regions:
fixNIGI =
Join[#[[1 ;; -2]],
ConstantArray[Missing[],
8], {#[[-1]]}, {Missing[]}] & /@ (Flatten /@
Transpose[{Select[
votingData, #[[1]] > 380 &], {QuantityMagnitude[
UnitConvert[
Entity["AdministrativeDivision", {"NorthernIreland",
"UnitedKingdom"}]["Area"], Quantity[1, (("Meters")^2)]]],
QuantityMagnitude[
UnitConvert[Entity["Country", "Gibraltar"]["Area"],
Quantity[1, (("Meters")^2)]]]}}]);
Then we can add the data to the table, create the input the linear model and estimate it:
collatedDatacomplete = Join[collatedData, fixNIGI];
inputLinearModelcomplete =
Flatten /@ Transpose[{# - Mean[#] &@ collatedDatacomplete[[All, 9]],
collatedDatacomplete[[All, 3]], # - Mean[#] &@ (collatedDatacomplete[[All, 6]]/collatedDatacomplete[[All, 30]]),
N[collatedDatacomplete[[All, 13]]/collatedDatacomplete[[All, 11]]]}];
lmodelcomplete = LinearModelFit[inputLinearModelcomplete, {turnout, region, popdensity}, {turnout, region, popdensity}, NominalVariables -> region]
lmodelcomplete["ParameterTable"]
![enter image description here][15]
The values match the result above quite well, obviously there is now a result for NI as well. The key thing about linear models is that one can combine the various areas to get a area weighted estimate for the election result. To achieve this we need to obtain the parameters from the table above.
parametermatrix = Delete[lmodelcomplete["ParameterTableEntries"], {{2}, {-1}}]
To achieve a area weighted result, we need to obtain the weights for each region which is defined as the number of entries per area divided by the total number of entries:
weights = N[#/Total[#]] &@RotateRight[SortBy[Tally[inputLinearModelcomplete[[All, 2]]], First]][[All, 2]]
As all parameters are given with respect to one area and present differences to this area, we need to add all estimates to the intercept, see example for Scotland above. This is achieved through linear algebra, by defining a so called contrast matrix.
contrast = IdentityMatrix[Length[weights]];
contrast[[1]] = ConstantArray[1, Length[weights]];
contrast = Transpose[contrast]
Multiplying the matrix to the parameter estimates gives the response functions, the model results for each area.
responsefunctions = contrast.parametermatrix[[All, 1]]
Multiplying this with the weights for each area results in a weighted mean for the UK. It is worth noting that this result is no longer influenced by the turnout and the average population density as these are 0 for the UK, as we subtracted their overall mean in the beginning.
weights.responsefunctions
So the model's referendum result would have been 52.99% in favour of leave, so higher than the actual result. Importantly, Linear Models provide errors for each parameter estimate, such that we can estimate the overall uncertainty of this result. As standard errors are not additive but variances are, we obtain the estimated standard error for this result as follows, assuming independence of the estimates
seresponsefunctions = contrast.(parametermatrix[[All, 2]]^2)
The final standard error is
Sqrt[weights.seresponsefunctions]
0.0255668. This means that best model guess is that 52.99% p/m 2.56% are in favour of leave, using a Gaussian approximation, this implies that there is a
Probability[x < -(weights.responsefunctions - 0.5)/Sqrt[weights.seresponsefunctions], x \[Distributed] NormalDistribution[0, 1]]
12.11% chance that this result was obtained although the majority of the UK electorate does actually not want to leave the EU. We emphasise that by no means are we challenging the result of the referendum, we are just arguing that given model assumptions the results obtained are actually compatible with a population split in which the majority does not want to leave the EU. In many fields such as Science and Medicine, a 12.11% 'risk' that the result is actually a false positive, i.e., the conclusions drawn and actions taken are wrong, is considered too high, 5% or 1% are typical values, in particle Physics the threshold is much lower. So it remains to be investigated if statements that the election results reflect the true opinion of the population. Again, we do not challenge the outcome of the election as there are clear rules to the election that are known in advance such as that it is everybody's free choice to vote or not and how the final result is obtained. There is just a potential non-causal link to people's real opinions, which is often assumed but not necessarily correctly so.
Getting more data...
----------
An interesting thing to check is whether we can learn something from adding additional data on the various voting districts. The data is from [here][16]. We import the file with the data
additionaldata = Import["EU-referendum-results-and-characteristics-data.xlsx"];
We also use the electoral region id data from above:
ids = collatedDatacomplete[[All, 4]];
Then we need to deal with incomplete data/clean the data up:
fillers = ConstantArray[Missing[], #] & /@ Length /@ additionaldata[[2 ;; 11, 4]];
We now can generate a fixed data table:
fulldatatable =
Table[Join[collatedDatacomplete[[k]], Flatten@Table[If[Length[#] > 0, #, fillers[[i - 1]]] &@
Select[additionaldata[[i]], MemberQ[#, ids[[k]]] &], {i, 2, 11}]] /. "" -> Missing[], {k, 1, Length[ids]}];
To better work with the data we then generate a look-up table for the various columns:
datadescriptors =
Rule @@@ (Transpose[{Range[Length[#]], #}] & @
Join[votingData[[1]], explanationShape[[1]],
additionaldata[[2, 9]], additionaldata[[3, 1]],
additionaldata[[4, 8]], additionaldata[[5, 9]],
additionaldata[[6, 8]], additionaldata[[7, 4]],
additionaldata[[8, 8]], additionaldata[[9, 4]],
additionaldata[[10, 3]], additionaldata[[11, 3]]])
![enter image description here][17]
The following shows again a part of the table of all the data we can use now:
![enter image description here][18]
We can then generate some first part of the input for the linear model.
inputLinearModel =
Flatten /@ Transpose[{# - Mean[#] &@ collatedData[[All, 9]], collatedData[[All, 3]], # - Mean[#] &@ (collatedData[[All, 6]]/collatedData[[All, 30]]),
N[collatedData[[All, 13]]/collatedData[[All, 11]]]}];
Again we need to clean the data
fulldatatable[[All, 198]] /. "#" -> Missing[]
subMissing[x_] := If[StringContainsQ[ToString[FullForm[x]], "Missing"], Missing[], x ]
SetAttributes[subMissing, Listable]
This generates the full input for the linear model:
inputLinearModelcomplete =
Flatten /@
Transpose[{fulldatatable[[All, 3]], (# - Mean[#]) &@
fulldatatable[[All,
9]], (# - Mean[#]) &@ (fulldatatable[[All, 6]]/
fulldatatable[[All, 30]]), (# -
Mean[DeleteMissing[#]]) &@ (subMissing /@ (fulldatatable[[
All, 198]]/fulldatatable[[All, 6]])), (# -
Mean[DeleteMissing[#]]) &@ (fulldatatable[[All, 243]] /.
"#" -> Missing[]), (# -
Mean[DeleteMissing[#]]) &@ (subMissing /@ (fulldatatable[[
All, 227]]/fulldatatable[[All, 6]])),
N[fulldatatable[[All, 13]]/fulldatatable[[All, 11]]]}];
Here are a couple of lines of the input data we choose for our linear model:
inputLinearModelcomplete[[1 ;; 20]] // TableForm
![enter image description here][19]
Some more cleaning:
inputLinearModelcomplete = Select[subMissing /@ inputLinearModelcomplete, ! MemberQ[#, Missing[]] &];
Next we fit the linear model:
lmodelfulldata =
LinearModelFit[inputLinearModelcomplete, {region, turnout, popdensity, highqual, earning, nchildren}, {region, turnout, popdensity, highqual,
earning, nchildren}, NominalVariables -> {region}];
lmodelfulldata["ParameterTable"]
![enter image description here][20]
It is easy to see that the income and the number of children in the household significantly influence the preference for/against Brexit. We now use the parameter matrix to compute the weights and contrasts as before:
parametermatrix = lmodelfulldata["ParameterTableEntries"][[1 ;; 12]];
weights = N[#/Total[#]] &@RotateRight[SortBy[Tally[inputLinearModelcomplete[[All, 2]]], First]][[All, 2]];
contrast = IdentityMatrix[Length[weights]];
contrast[[1]] = ConstantArray[1, Length[weights]]; contrast = Transpose[contrast];
With the contrasts we can calculate the response functions:
responsefunctions = contrast[[1 ;; 12, 1 ;; 12]].parametermatrix[[1 ;; 12, 1]]
What is the best estimate for the "will of the voters"?
----------
We an now also use the linear model to estimate what the most likely scenario (based on the model) for the "underlying will of the voter" is given the data from above and the result of the election. We first prepare the data we need, which this time includes the outcome of the election.
inputLinearModelcompletewRcode =
Flatten /@
Transpose[{fulldatatable[[All, 4]],
fulldatatable[[All, 3]], (# - Mean[#]) &@
fulldatatable[[All,
9]], (# - Mean[#]) &@ (fulldatatable[[All, 6]]/
fulldatatable[[All, 30]]), (# -
Mean[DeleteMissing[#]]) &@ (subMissing /@ (fulldatatable[[
All, 198]]/fulldatatable[[All, 6]])), (# -
Mean[DeleteMissing[#]]) &@ (fulldatatable[[All, 243]] /.
"#" -> Missing[]), (# -
Mean[DeleteMissing[#]]) &@ (subMissing /@ (fulldatatable[[
All, 227]]/fulldatatable[[All, 6]])),
N[fulldatatable[[All, 13]]/fulldatatable[[All, 11]]]}];
This is how the data looks:
inputLinearModelcompletewRcode[[1 ;; 20]] // TableForm
![enter image description here][21]
Again we clean the data a bit:
inputLinearModelcompletewRcode = Select[subMissing /@ inputLinearModelcompletewRcode, ! MemberQ[#, Missing[]] &];
Now we can use the linear model to estimate the actual percentage of yes/no votes in the different voting areas:
codepercent = Transpose[{inputLinearModelcompletewRcode[[All, 1]], MapThread[lmodelfulldata, Transpose[inputLinearModelcompletewRcode[[All, 2 ;; -2]]]]}]
First we represent the actual election outcome. Green corresponds to "Remain" and red to "Leave" votes.
Graphics[Flatten[
Table[{ColorData[
"RedGreenSplit"][((Select[
Select[votingData[[2 ;;]], #[[1]] < 381 &], #[[4]] ==
translateshpvoteclean[[k, 2]] &][[1]])[[-3]]/100.)],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1, 380}],
1], Background -> Black, AspectRatio -> GoldenRatio]
![enter image description here][22]
We can now calculate the best estimate of the Leave/Remain split based on our model:
polygonscoloured =
Table[{ColorData["RedGreenSplit"][1. - ((Select[codepercent, #[[1]] == translateshpvoteclean[[k, 2]] &][[1]])[[-1]]) /. Missing[] -> 0.],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1, Length[translateshpvote]}];
Graphics[polygonscoloured, AspectRatio -> GoldenRatio, Background -> Black]
![enter image description here][23]
The split between England and Scotland has become even more pronounced. Note that we haven't dealt very cleanly with the few missing data cases. Next, we can compare the outcome of the elections with the best estimate of the actual Remain/Leave distribution.
Next, we compare the election outcome to our best model estimate:
GraphicsRow[{
Graphics[
Flatten[Table[{ColorData[
"RedGreenSplit"][((Select[
Select[votingData[[2 ;;]], #[[1]] < 381 &], #[[4]] ==
translateshpvoteclean[[k, 2]] &][[1]])[[-3]]/100.)],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1,
380}], 1], Background -> Black, AspectRatio -> GoldenRatio],
Graphics[Table[{ColorData["RedGreenSplit"][
1 - ((Select[
codepercent, #[[1]] ==
translateshpvoteclean[[k, 2]] &][[1]])[[-1]]) /.
Missing[] -> 0.],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1,
Length[translateshpvote]}], Background -> Black,
AspectRatio -> GoldenRatio],
Graphics[Flatten[
Table[{ColorData[
"RedGreenSplit"][(0.5 +
3.*((1 - ((Select[
codepercent, #[[1]] ==
translateshpvoteclean[[k, 2]] &][[1]])[[-1]] /.
Missing[] ->
0.)) - ((Select[
Select[votingData[[2 ;;]], #[[1]] <
381 &], #[[4]] ==
translateshpvoteclean[[k, 2]] &][[1]])[[-3]]/
100.)))],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1,
380}], 1], Background -> Black, AspectRatio -> GoldenRatio]},
ImageSize -> Full]
![enter image description here][24]
On the left we have the outcome of the elections. In the middle we represent the estimate of the remain/leave ratio based on our linear model. The right figure shows the size of the "correction". The model shows a strong separation between Scotland and most regions in England. The exception in England is the region around London.
Area weighted model
----------
Next we will pool the different regions to better understand regional difference.
codepercent = Transpose[{inputLinearModelcompletewRcode[[All, 1]], MapThread[lmodelfulldata, Transpose[inputLinearModelcompletewRcode[[All, 2 ;; -2]]]]}]
We basically set all the inputs to zero apart from the region data
codepercentregion =
Transpose[{inputLinearModelcompletewRcode[[All, 1]],
MapThread[lmodelfulldata,
Transpose[(Flatten /@
Transpose[{inputLinearModelcompletewRcode[[All, 1 ;; 2]],
ConstantArray[0, {382, 6}]}])[[All, 2 ;; -2]]]]}];
GraphicsRow[{Graphics[
Flatten[Table[{ColorData[
"RedGreenSplit"][((Select[
Select[votingData[[2 ;;]], #[[1]] < 381 &], #[[4]] ==
translateshpvoteclean[[k, 2]] &][[1]])[[-3]]/100.)],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1,
380}], 1], Background -> Black, AspectRatio -> GoldenRatio],
Graphics[Table[{ColorData["RedGreenSplit"][
1 - (((If[# == {}, {Select[
votingData, #[[4]] ==
translateshpvoteclean[[k, 2]] &][[1, {4, -2}]]/{1,
100.}}, #] &@
Select[codepercentregion, #[[1]] ==
translateshpvoteclean[[k, 2]] &])[[1]])[[-1]])],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1,
Length[translateshpvote]}], Background -> Black,
AspectRatio -> GoldenRatio],
Graphics[Flatten[
Table[{ColorData[
"RedGreenSplit"][(0.5 +
3.*((1 - (((If[# == {}, {Select[
votingData, #[[4]] ==
translateshpvoteclean[[k, 2]] &][[1, {4, -2}]]/{1,
100.}}, #] &@
Select[
codepercentregion, #[[1]] ==
translateshpvoteclean[[k, 2]] &])[[
1]])[[-1]])) - (((If[# == {}, {Select[
votingData, #[[4]] ==
translateshpvoteclean[[k, 2]] &][[1, {4, -2}]]/{1,
100.}}, #] &@
Select[
Select[
votingData[[2 ;;]], #[[1]] < 381 &], #[[4]] ==
translateshpvoteclean[[k, 2]] &])[[1]])[[-3]]/
100.)))],
localauthorities[[1, 2, 1, 2, 1, 2, 1, 1, 1]][[k]]}, {k, 1,
380}], 1], Background -> Black, AspectRatio -> GoldenRatio]},
ImageSize -> Full]
![enter image description here][25]
This provides the smoothed picture as regions are pooled and weighted according to their representation in the UK. As before the leftmost image represents the outcome of the election, the middle one is the best region weighted estimate and the right figure shows the differences. The strong divide between the different regions is enhanced in this representation.
Population weighted representation
----------
The representations above have the critical drawback that equal area sizes do not necessarily correspond to equally sized electorates. We can represent everything such that area corresponds to population size. This will decrease the size of the regions with low population densities such as Scotland. The following file (attached) contains a hexagonal lattice that describes the areas in the UK.
hexagonshape = Import["GB_Hex_Cartogram_LAs.shp"]
![enter image description here][26]
The following file contains a lookup table of regions vs area codes.
hexagonlegend = Import["GB_Hex_Cartogram_LAs.dbf"];
hexagonlegend[[1 ;; 10, {3, 2}]] // TableForm
![enter image description here][27]
We now need to translate between the hexagonal structure and the voting areas from our model.
tranlatehexagonvoteclean =
Table[Select[hexagonlegend, #[[2]] == translateshpvoteclean[[i, 2]] &], {i, 1,Length[translateshpvoteclean]}][[All, 1, 1]];
We can then represent the estimate from our model in an population/area adjusted representation.
Graphics[Table[{ColorData["RedGreenSplit"][1 - (( If[# == {}, {Select[votingData, #[[4]] ==
translateshpvoteclean[[k, 2]] &][[1, {4, -2}]]/{1, 100.}}, #] &@
Select[codepercent, #[[1]] == translateshpvoteclean[[k, 2]] &])[[1]][[-1]]) /. Missing[] -> 0.],
hexagonshape[[1, 2, 1, 2]][[tranlatehexagonvoteclean[[k]]]]}, {k, 1, Length[tranlatehexagonvoteclean]}], Background -> Black]
![enter image description here][28]
Preliminary summary
----------
These calculations show that we might have to perform some sort of estimation procedure to better understand the "will of the people". The method we have used is quite standard in for example medical studies. This is, however, not a suitable way of decision making in societies. As said many times before, the decision is based on an agreed upon procedure. It is not based on a statistical analysis of the data, which as in our case is model dependent.
Bootstrapping
----------
Note, that there are different approaches to try to mathematically guesstimate what the people who did not vote think about Brexit. Alternatively to the method described above we could pool all data from all local authorities and scale up to the entire electorate (unnecessary) and bootstrap on that.
The argument of many politicians would be that the non-voters essentially behave like the voters. In that case we basically scale up the results from the voters to the entire electorate. The bootstrapping in this case would look like this:
Monitor[fullpoolresults =
Table[Count[RandomChoice[Total /@ Transpose[{N@#[[13]]/#[[11]]*#[[6]], #[[6]] - N@#[[13]]/#[[11]]*#[[6]]} & /@ (Reverse@
SortBy[votingData[[2 ;;]], #[[9]] &])] -> {"Leave", "Remain"}, 46500001], "Remain"]/46500001., {i, 1, 100}];, i]
We can fit a smooth kernel distribution to the outcomes of the bootstrapping procedure:
distfullpool = SmoothKernelDistribution[fullpoolresults]
As expected the probability that more than 50% of the electorate would have wanted to Remain is (numerically) zero.
Probability[x > 0.50, x \[Distributed] distfullpool]
(*0*)
So, under this model assumption it is certain that people really wanted Brexit.
The assumption that the electorate is that homogeneous is quite questionable. We might therefore choose to bootstrap with respect to the local authorities. In other words, we assume that it is on the authority level that voters are similar.
Monitor[localauthresults =
Table[N@(Total[#[[All, 13]]/#[[All, 11]]*#[[All, 6]]]/
Total[#[[All, 6]]]) &@
RandomChoice[(Reverse@SortBy[votingData[[2 ;;]], #[[9]] &])[[All,
6]] -> (Reverse@SortBy[votingData[[2 ;;]], #[[9]] &]),
Length[votingData[[2 ;;]]]], {i, 1, 1000}], I];
This bootstraps for the percentage of Remain votes. We can then again fit a distribution:
distlocalauthorities = SmoothKernelDistribution[localauthresults]
and plot the result:
Plot[PDF[distlocalauthorities, x], {x, 0.45, 0.55}, PlotRange -> All,
FrameLabel -> {"percent leave", "probablity density"},
LabelStyle -> Directive[Bold, 18], ImageSize -> Large,
PlotTheme -> "Marketing"]
![enter image description here][29]
This means that the average of the bootstrap results for Remain votes is below 50%.
Mean[distlocalauthorities]
0.494498. This is, however, quite close to 50%. There is a substantial area above the 50% level:
Probability[x > 0.50, x \[Distributed] distlocalauthorities]
0.17122. This suggests that there is a 17% probability that the voter actually wanted to tell us that they want to remain. This is a substantial fraction/probability. Under these assumptions it is by no means clear that the electorate wanted to leave. Once again, this is not how we take democratic decisions. The decision making process is determined by the outcome of the election and not by an estimate of the voters' will. The point is that it is questionable whether politicans can claim that the voters' will is clear.
The last approach is to bootstrap over the local authorities according to the number of ballots cast:
localvotersresults =
Table[N@(Total[#[[All, 13]]]/Total[#[[All, 11]]]) &@RandomChoice[(Reverse@SortBy[votingData[[2 ;;]], #[[9]] &])[[All, 11]] -> (Reverse@SortBy[votingData[[2 ;;]], #[[9]] &]), Length[votingData[[2 ;;]]]], {10000}];
Once more we estimate the distribution:
localvotersdist = SmoothKernelDistribution[localvotersresults]
and plot the resulting probability density function:
Plot[PDF[localvotersdist, x], {x, 0.45, 0.55}, PlotRange -> All,
FrameLabel -> {"percent leave", "probablity density"},
LabelStyle -> Directive[Bold, 18], ImageSize -> Large,
PlotTheme -> "Marketing"]
![enter image description here][30]
Probability[x < 0.50, x \[Distributed] localvotersdist]
0.487381. So under this assumption we would interpret the voters' will as nearly completely undecided. There is a 50%/50% split, i.e. it is practically equally likely that the voters wanted to remain as that voters wanted to leave.
Conclusion
----------
"The will of the voters" is difficult to understand in close elections. It is by no means as clear that the winning alternative of an election represents the "will of the people" when elections are very close. Politicians often like to stress that they represent the will of the people after winning an election. Mathematically speaking, this is not necessarily true. Note, that this is irrelevant for the decision making process. As a society we have decided to abide by fixed electoral rules. Only people who actually vote will make their voices heard. We can mathematically try to figure out what the entire electorate wanted, or to be precise make probability statements about what they wanted. These statements are clearly model dependent.
[1]: http://community.wolfram.com/groups/-/m/t/1221950
[2]: http://community.wolfram.com/web/bschelter
[3]: https://www.electoralcommission.org.uk/find-information-by-subject/elections-and-referendums/past-elections-and-referendums/eu-referendum/electorate-and-count-information
[4]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1600.47.30.png&userId=48754
[5]: http://esriuktechnicalsupportopendata-techsupportuk.opendata.arcgis.com/datasets/686603e943f948acaa13fb5d2b0f1275_0
[6]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1600.55.48.png&userId=48754
[7]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1600.59.21.png&userId=48754
[8]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.01.56.png&userId=48754
[9]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.09.35.png&userId=48754
[10]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.09.59.png&userId=48754
[11]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.12.00.png&userId=48754
[12]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.12.45.png&userId=48754
[13]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.13.40.png&userId=48754
[14]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.17.37.png&userId=48754
[15]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.20.53.png&userId=48754
[16]: https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwihifGz0cHXAhXHKcAKHdtTDU0QFggmMAA&url=http://researchbriefings.files.parliament.uk/documents/CBP-7639/EU-referendum-results-and-characteristics-data.xlsx&usg=AOvVaw3RFJU1dCOJM-tukE0VZGpx
[17]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.28.13.png&userId=48754
[18]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.29.24.png&userId=48754
[19]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.32.00.png&userId=48754
[20]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.33.34.png&userId=48754
[21]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.37.36.png&userId=48754
[22]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.39.19.png&userId=48754
[23]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.40.41.png&userId=48754
[24]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.42.25.png&userId=48754
[25]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.44.22.png&userId=48754
[26]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.47.25.png&userId=48754
[27]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.49.14.png&userId=48754
[28]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.51.29.png&userId=48754
[29]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.55.45.png&userId=48754
[30]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1601.58.42.png&userId=48754Marco Thiel2017-11-16T02:01:31ZClassifying Japanese characters from the Edo period
http://community.wolfram.com/groups/-/m/t/1221098
Introduction
----------
I recently came across a post for a computer program that in some fields intends to compete with the Wolfram Language and which has a toolbox for Machine Learning. I wanted to compare the work described with the workflow in Mathematica. The challenge is to classify old Japanese Characters from texts from the so-called Edo period:
Style[StringTake[WikipediaData["Edo period"], 601], 16]
![enter image description here][1]
The characters are written in running style and apparently are difficult to read for Japanese speakers today. We will use two approaches of machine learning in the Wolfram Language to tackle this problem.
Historical Background
-----------------------------
Before we proceed, let's have a look at the Tokugawa shogunate. I will use code borrow from [@Vitaliy Kaurov][at0] from his great article on ["Computational history: countries that are gone"][2]. The following lines compute the historic boundaries of the shogunate:
Monitor[tokugawaPOLY =
Table[EntityValue[Entity["HistoricalCountry", "TokugawaShogunate"],
EntityProperty["HistoricalCountry",
"Polygon", {"Date" -> DateObject[{t}]}]], {t, 1600, 1870}];, t]
We then only filter for "changes" in the boundaries:
tokugawaPOLY // Length
tokugawaPOLYcomp =
DeleteMissing[
DeleteDuplicates[Transpose[{Range[1600, 1870], tokugawaPOLY}],
Last[#1] == Last[#2] &], 1, 2];
tokugawaPOLYcomp // Length
In the 271 I consider in the first place there are only 4 changes to the boarders, which we can plot like so:
GeoGraphics[{EdgeForm[Red], GeoStyling[Opacity[.1]], #} & /@
tokugawaPOLYcomp[[All, 2]], GeoProjection -> "Mercator",
ImageSize -> 800, GeoBackground -> GeoStyling["StreetMap"],
GeoRange -> Entity["Country", "Japan"],
GeoRangePadding -> Quantity[800, "Kilometers"], GeoZoomLevel -> 6]
![enter image description here][3]
So the boarders were indeed very stable for a long period reflecting the "no more wars" philosophy of the day.
Arts and culture
----------
The stability led to a very rich art and literature scene. Here are some images that reflect the style of the time:
ImageCollage["Thumbnail" /. Normal[Normal[WebImageSearch["Edo Period"]]], Method -> "Rows"]
![enter image description here][4]
Our dataset
----------
Also literature flourished during this period. Our dataset will be taken from the [Center for Open Data in the Humanities][5]. The keen reader might have noticed that the page is in Japanese. Mathematica can translate the page, and [so can Google][6]. The dataset is called the "Japanese classic registered glyph data set"; 日本古典籍字形データセット.
TextTranslation["日本古典籍字形データセット"]
"Japan classics-type datasets". Following the first link (grey box) on the original Japanese page one gets to t[his page][7], from the bottom of which (look for a download symbol and the text "(TAR+GZ 24.57 MB)" the dataset can be downloaded. This is the google translation of the reference:
> Japanese Classic Statement Character Data Set" (Kokugaku Kenkyu Other
> Collection / CODH Processing)
which in the original is "日本古典籍字形データセット』（国文研ほか所蔵／CODH加工".
The glyphs come from "bamboo letters" from 15 classic texts; the dataset contains more than 20000 glyphs of the 10 most frequent symbols. These letters were annotated by the "National Institute of Letters of Japan" (google). The dataset was also used in a [data/machine learning challenge][8].
After extracting the file to a folder on the desktop I can import the images with:
characterImages = Import["/Users/thiel/Desktop/pmjt_sample_20161116/train_test_file_list.h5", "Data"];
Here is a sample of the glyphs:
Grid[Partition[ImageAdjust[Image[#/256.]] & /@ characterImages[[3, 1 ;; 24]], 6], Frame -> All]
![enter image description here][9]
Similar to the MNIST dataset, they consist of 28 times 28 pixels. They give the grey level as integers, which is why I divide by 256. This shows the pixelation of the glyphs:
Image[characterImages[[3, 12]]/256.] // ImageAdjust
![enter image description here][10]
The dataset conveniently contains a training and a test set. There are
characterImages[[3]] // Length
19909 glyphs in the training set. All of these are annotated:
Flatten[characterImages[[4]]]
![enter image description here][11]
We can convert the training data to images like so:
Monitor[trainingset = Table[ImageAdjust[Image[characterImages[[3, k]]/256.]] -> Flatten[characterImages[[4]]][[k]], {k, 1, 19909}];, k]
The test set contains
characterImages[[1]] // Length
3514 glyphs. The annotation of which are found in
characterImages[[2]] // Flatten // Short
![enter image description here][12]
This is how we prepare the test set data for our machine learning:
Monitor[testset = Table[ImageAdjust[Image[characterImages[[1, k]]/256.]] -> Flatten[characterImages[[2]]][[k]], {k, 1, 3514}];, k]
What are the 10 most frequent symbols?
----------
In one of the annotation files we find the character codes of the symbols so that we can map the classification to actual symbols. These are the glyphs we will consider:
Rasterize /@ (Style[
FromCharacterCode[
ToExpression["16^^" <> StringJoin[Characters[#]]]],
100] & /@ {"3057", "306B", "306E", "3066", "308A", "3092",
"304B", "304F", "304D", "3082"})
![enter image description here][13]
We can also make an image collage of them:
ImageCollage[
Image /@ (Rasterize /@ (Style[
FromCharacterCode[
ToExpression["16^^" <> StringJoin[Characters[#]]]],
100] & /@ {"3057", "306B", "306E", "3066", "308A", "3092",
"304B", "304F", "304D", "3082"})), Method -> "Rows"]
![enter image description here][14]
I though it would be nice if they were in a more calligraphic form. So I tried to used ImageRestyle to try and make them more calligraphic. I think that the attempt was not very successful, but I want to show it anyway.
First I download a couple of calligraphic symbols:
caligraphy = "Thumbnail" /. Normal[Normal[WebImageSearch["japanese calligraphy"]]]
I liked the 5th one, which I will use for the style transfer:
calisymbols =
ImageRestyle[#, caligraphy[[5]],
PerformanceGoal ->
"Quality"] & /@ (Rasterize /@ (Style[
FromCharacterCode[
ToExpression["16^^" <> StringJoin[Characters[#]]]],
100] & /@ {"3057", "306B", "306E", "3066", "308A", "3092",
"304B", "304F", "304D", "3082"}))
![enter image description here][15]
We can also remove the background to get an alternative representation:
![enter image description here][16]
Machine Learning (Classify)
----------
Our first approach to classify the glyphs will be via Classify. The classification is very fast (only a couple of seconds on my machine) and quite accurate:
standardcl = Classify[trainingset, ValidationSet -> testset, PerformanceGoal -> "Quality"]
We can first calculate the ClassifierMeasurements
cmstandard = ClassifierMeasurements[standardcl, testset]
and the accuracy:
cmstandard["Accuracy"]
With 92.5% this is quite accurate and also much faster than the competitor product. The confusion plot shows that it is a very reasonable accuracy - in particular when considering that native speakers have problems identifying the glyphs.
cmstandard["ConfusionMatrixPlot"]
![enter image description here][17]
Here are some glyphs that the Classifier identified as class "0":
cmstandard["Examples" -> {0, 0}][[1 ;; 20]]
![enter image description here][18]
They look quite diverse, but so does the original set:
RandomSample[Select[trainingset, #[[2]] == 0 &], 20]
![enter image description here][19]
It is quite impressive that the Classify function manages to achieve this level of accuracy. We can, however, do better!
Machine Learning (NetTrain)
----------
We can improve the accuracy by training our own custom made network, which in this case will be the standard net that is often used for the MNIST dataset in Mathematica. It turns out that we do not even need a GPU for the training.
lenet = NetChain[{ConvolutionLayer[20, 5], Ramp, PoolingLayer[2, 2],
ConvolutionLayer[50, 5], Ramp, PoolingLayer[2, 2], FlattenLayer[],
500, Ramp, 10, SoftmaxLayer[]},
"Output" -> NetDecoder[{"Class", Range[0, 9]}],
"Input" -> NetEncoder[{"Image", {28, 28}, "Grayscale"}]]
![enter image description here][20]
This we can then train:
lenet = NetTrain[lenet, trainingset, ValidationSet -> testset, MaxTrainingRounds -> 20];
![enter image description here][21]
The training is done in about 4:30 minutes, but it appears that 20 training rounds are not necessary. Here are some results when applying the classifier:
imgs = Keys@RandomSample[testset, 60]; Thread[imgs -> lenet[imgs]]
![enter image description here][22]
Let's see how well it does:
cm = ClassifierMeasurements[lenet, testset]
cm["ConfusionMatrixPlot"]
![enter image description here][23]
This corresponds to an accuracy of
cm["Accuracy"]
95.6%, which is really impressive given the dataset. The following table illustrates the difficulty:
Grid[Table[
Prepend[Select[trainingset, #[[2]] == k &][[1 ;; 10]][[All, 1]],
ImageResize[calisymbols[[k + 1]], 28]], {k, 0, 9}], Frame -> All,
Background -> {{Red}, None}]
![enter image description here][24]
The first (red) column is derived from the glyph based on the character code - using our "calligraphy-style". The remaining columns show items from the training set, i.e. glyphs that were manually classified to belong to the given group.
Conclusion
----------
I do not speak/read Japanese and have no more than Wikipedia knowledge about the Edo period. I still find it quite amazing that using the Wolfram Language's high level Classify function and one of the pre-implemented networks, we can achieve quite a remarkable classification. I am sure that the network can be improved. I would also like to see a more complete dataset with more than 10 different symbols.
[at0]: http://community.wolfram.com/web/vitaliyk
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-13at23.24.03.png&userId=48754
[2]: http://community.wolfram.com/groups/-/m/t/852277
[3]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-13at23.30.18.png&userId=48754
[4]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-13at23.33.24.png&userId=48754
[5]: http://codh.rois.ac.jp/char-shape/
[6]: https://translate.google.com/translate?hl=en&sl=auto&tl=en&u=http://codh.rois.ac.jp/char-shape/
[7]: http://codh.rois.ac.jp/char-shape/book/
[8]: https://translate.google.com/translate?hl=en&sl=ja&tl=en&u=http://codh.rois.ac.jp/seminar/japanese-character-challenge-20170210/&sandbox=1
[9]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-13at23.56.19.png&userId=48754
[10]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-13at23.57.57.png&userId=48754
[11]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-13at23.59.36.png&userId=48754
[12]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.01.19.png&userId=48754
[13]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.04.22.png&userId=48754
[14]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.05.04.png&userId=48754
[15]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.07.44.png&userId=48754
[16]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.08.53.png&userId=48754
[17]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.15.09.png&userId=48754
[18]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.17.07.png&userId=48754
[19]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.18.25.png&userId=48754
[20]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.21.43.png&userId=48754
[21]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.22.50.png&userId=48754
[22]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.27.23.png&userId=48754
[23]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.28.27.png&userId=48754
[24]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at00.40.41.png&userId=48754Marco Thiel2017-11-14T00:49:30ZAridity, an arcGRID import problem
http://community.wolfram.com/groups/-/m/t/1222924
There's publicly available data database of aridity and PET, that is precipitation/evaporation/transpiration
http://www.cgiar-csi.org/data/global-aridity-and-pet-database
It's a raster on a 10 arc-second grid. It should be importable using a command like this
Import[ "http://exampledata.wolfram.com/ArcGRID.zip"], which works with the example data set.
But I get this error message with the (several hundred megabyte) aridity dataset downloaded to my machine.
LinkObject::linkd: Unable to communicate with closed link LinkObject['/Applications/Mathematica.app/Contents/SystemFiles/Converters/Binaries/MacOSX-x86-64/GDAL.exe',588130,13].
Import::fmterr: Cannot import data as ArcGRID format.
Any wisdom from this crowd?Daniel Seligson2017-11-15T23:23:16ZHTML Import is not working
http://community.wolfram.com/groups/-/m/t/1222542
Hi. I am trying to use Import to read a webpage, but it doesn't seem to work. Please help.
website = "https://www.cse.lk/home/company-info/JKH.N0000/announcements"
websiteData = Import[website]
websiteData just ends up as a blank string.
Any help would be much appreciated. Thank you.
Priyan.Priyan Fernando2017-11-15T09:39:27ZSpeedup DiscretizePDE when InitializePDECoefficients contains Interpolation
http://community.wolfram.com/groups/-/m/t/1222183
I work on FEM in Mathematica and want to speed up the computation when dealing with very fined mesh (i.e., a huge number of DOF).
I found that a very much longer time is consumed when the Coefficients of PDE contains interpolation functions, compared to the case that the Coefficients are constants. To be more specific, let consider the following exemplary code.
ClearAll["Global`*"]
SetDirectory[NotebookDirectory[]];
Needs["NDSolve`FEM`"];
width = 1.0; heigth = 2.0; ydatum = 0.0;
\[ScriptCapitalR] =
ImplicitRegion[0 <= x <= width && ydatum <= y <= heigth + ydatum , {x, y}];
RegionPlot[\[ScriptCapitalR], AspectRatio -> Automatic, ImageSize -> Small]
pde = {Div[{{\[Lambda] + 2 \[Mu], 0}, {0, \[Mu]}}.Grad[
u[x, y], {x, y}] + {{0, \[Lambda]}, {\[Mu], 0}}.Grad[
v[x, y], {x, y}], {x, y}],
Div[{{0, \[Mu]}, {\[Lambda], 0}}.Grad[
u[x, y], {x, y}] + {{\[Mu], 0}, {0, \[Lambda] + 2 \[Mu]}}.Grad[
v[x, y], {x, y}], {x, y}]};
\[CapitalGamma]g = {DirichletCondition[u[x, y] == 0, x == 0],
DirichletCondition[v[x, y] == 0, y == ydatum],
DirichletCondition[v[x, y] == 0.2, y == heigth + ydatum]};
\[Lambda] = 1.0; \[Mu] = 1.0;
{dPDE, dBC, vd, sd, md} =
ProcessPDEEquations[{pde == {0, 0}, \[CapitalGamma]g}, {u,
v}, {x, y} \[Element] \[ScriptCapitalR],
Method -> {"FiniteElement",
"MeshOptions" -> {"ImproveBoundaryPosition" -> False,
"MaxCellMeasure" -> 0.0001, "MeshOrder" -> 2}}];
mesh2 = md["ElementMesh"];
linearLoad = dPDE["LoadVector"];
linearStiffness = dPDE["StiffnessMatrix"];
diriPos = dBC["DirichletRows"];
offsets = md["IncidentOffsets"];
md["DegreesOfFreedom"]
Show[mesh2["Wireframe"]]
ClearAll[rhs]
tol = 10^-8;
err = 1.0;
iter = 0;
\[Alpha] = 1.0;
rhs[uIn_] := Module[{uOld}, uOld = uIn;
While[err >= tol && iter <= 20,
u0 = ElementMeshInterpolation[{mesh2},
uOld[[offsets[[1]] + 1 ;; offsets[[2]]]]];
v0 = ElementMeshInterpolation[{mesh2},
uOld[[offsets[[2]] + 1 ;; offsets[[3]]]]];
nlPdeCoeff = InitializePDECoefficients[vd, sd,
"LoadCoefficients" -> -{{0}, {-1}},
"LoadDerivativeCoefficients" -> {{{(\[Lambda] + 2 \[Mu]) D[
u0[x, y], x] + \[Lambda] D[v0[x, y],
y], \[Mu] (D[u0[x, y], y] +
D[v0[x, y], x])}}, {{\[Mu] (D[u0[x, y], y] +
D[v0[x, y], x]), \[Lambda] D[u0[x, y],
x] + (\[Lambda] + 2 \[Mu]) D[v0[x, y], y]}}},
"ReactionCoefficients" -> {{0, 0}, {0,
0}}];
t1 = AbsoluteTime[];
nlsys = DiscretizePDE[nlPdeCoeff, md, sd];(*time ~s*)
time1 = AbsoluteTime[] - t1;
nlLoad = nlsys["LoadVector"];
nlStiffness = nlsys["StiffnessMatrix"];
ns = nlStiffness + linearStiffness;
nl = nlLoad + linearLoad;
nl[[diriPos]] = {0.};
ns[[diriPos, All]] = 0.;
ns[[All, diriPos]] = 0.;
(ns[[#, #]] = 1.) & /@ diriPos;
dU = LinearSolve[ns, nl];
Print[iter, " Residual: ", Norm[nl, Infinity], " Correction: ",
Norm[dU, Infinity], " Time: ", time1];
err = Norm[nl, Infinity]; iter++;
uOld = uOld + \[Alpha]*dU;];
uOld]
uOld = ConstantArray[{0.}, md["DegreesOfFreedom"]];
uOld[[diriPos]] = dBC["DirichletValues"];
uNew = rhs[uOld];
The "LoadDerivativeCoefficients" already contain the interpolated function u0 and v0, the other Coefficients are constants. After timing each command during running, I found the DiscretizePDE is most time consuming. For example, in this case, the DiscretizePDE command will cost ~6 seconds during each iteration.
On the other hand, if we set InitializePDECoefficients as:
nlPdeCoeff = InitializePDECoefficients[vd, sd,
"LoadCoefficients" -> -{{0}, {-v0[x, y]^2}},
"LoadDerivativeCoefficients" -> {{{(\[Lambda] + 2 \[Mu]) D[
u0[x, y], x] + \[Lambda] D[v0[x, y],
y], \[Mu] (D[u0[x, y], y] +
D[v0[x, y], x])}}, {{\[Mu] (D[u0[x, y], y] +
D[v0[x, y], x]), \[Lambda] D[u0[x, y],
x] + (\[Lambda] + 2 \[Mu]) D[v0[x, y], y]}}},
"ReactionCoefficients" -> {{0,
0}, {0, -2 v0[x,
y]}}];
Now the time of running DiscretizePDE is ~10 seconds. If we refine the mesh, the consumed time will increase. (The above code is running with 16 cores.)
Since I need to run a lot of such code. Is there a way to cut of the time that the DiscretizedPDE needs when InitializePDECoefficients contains Interpolation functions?Wilhelm Deng2017-11-15T18:19:37ZThe voters have spoken - but what did they say?
http://community.wolfram.com/groups/-/m/t/1221950
Introduction
----------
Elections are fundamental to our democracies and way of life. The electorate bestows power on the lawmakers and public officials whose legitimisation is derived solely from the fact that they are elected. In recent times, many elections, such as the presidential elections the United States and the Brexit and general elections in the United Kingdom have seen a very pronounced polarisation the electorate. Can mathematics and the Wolfram Language help to better understand this crucial process of the most fundamental decision making process in societies? The main question I want to discuss in a sequence of posts is what can be learnt from elections. So this post is about **computational politics**.
It is important to notice that democracies rely on a general acceptance of the result of elections. Without that consensus a peaceful co-existence is at risk. Societies agree on certain electoral procedures and the results have to be understood to be final. There are, however, more fundamental questions such as how do we derive the "voters will" from ballots. That is a highly non-trivial problem. Also, elected politicians often claim that they represent the "will of the people". But is that true and what is the "will of the people"? Hence, my question: the voters have spoken - but what did they say?
This is the first of a series of posts (hopefully):
1. **Electoral systems - interpreting the will of the voters**
2. Gerrymandering - shaping the voters' will to your liking
3. [Analysis of the Brexit vote - how do we know what did the voters really want?][1]
I apologise because there won't be any nice graphics in this post, but I find the results relevant anyway. In the following posts we will apply some more sophisticated algorithms to try to figure out what the voters meant to tell us. We will then see that we can use mathematics to estimate what the voters might have wanted to tell us; and then we can correct for that.
![enter image description here][2]
Note, that this cannot be the procedure by which we determine the decision that the electorate have taken. This is all a bit confusing, but I hope that it will become a bit clearer in these posts.
All posts were developed with [Bjoern Schelter][3], who is also a member of this community. The definitions and main ideas for this post were taken from the excellent book ["Mathematics And Politics: Strategy, Voting, Power, and Proof"][4] by Alan Taylor, a text which I highly recommend. It is a treasure trove of ideas and concepts for anyone interested in this ares. It goes far beyond what is described in this post.
Social choice procedure
----------
It turns out that reading the voters' will from a ballot is much more complicated than one might think - in many situations it is impossible (mathematically provable!) to do so in a "good" way. Let's define some words first. Let's assume that each voter ranks some alternatives in their preferred order.
**Definition:** A social choice procedure is a function for which a typical input is a sequence of lists (without ties) of some set A (the set of alternatives) and the corresponding output is either an element of A, a subset of A, of "No Winner".
There is a beautiful theorem by May (1952):
**Theorem:**
If the number of people is odd and each election produces a unique winner, then the majority rule is the only social choice procedure for two alternatives that satisfies the following three conditions:
1. It treats all the voters the same: If any two voters exchange their ballots, the outcome of the election is un-effected.
2. It threats both alternatives the same: If every voter reverses his or her vote (changing a vote for a to a vote for b and vice versa), the the election outcome is reversed as well.
3. It is monotone: If some voter were to change his or her ballot from a vote for the loser to a vote for the winner, then the election outcome would be unchanged.
Six examples of social choice procedures
----------
Let us assume that we have several alternatives to be voted for:
alternatives = {a, b, c}
Then there are the voting lists of the voters. They form the ballots:
ballots = Table[RandomSample[alternatives, Length[alternatives]], {k, 4}]
(*{{a, b, c}, {c, b, a}, {a, b, c}, {a, b, c}}*)
> Condorcet's method:
>
> An alternative x is among the winners if for any other alternative y,
> at least half of the voters rank x over y on their ballots.
This is an implementation of this social choice function:
condorcetindiv[ballots_List, a_, b_] :=
Module[{},
If[a === b, "NA",
If[#[[1, 2]] >= Length[ballots]/2, {a, b}, #[[-1, 1, 1]]] &@
SortBy[Tally[Select[#, # == a || # == b &] & /@ ballots], Last]]]
condorcet[ballots_List, alternatives_] :=
Module[{},
If[Max[#] >= Length[ballots],
alternatives[[
Flatten[Position[#, Max[#]]]]], {}] &@(Count[
Flatten[Outer[condorcetindiv[ballots, #1, #2] &, alternatives,
alternatives], Infinity], #] & /@ alternatives)]
Given the ballots and the alternatives we can now compute the social choice by applying the function condorcet:
condorcet[ballots, alternatives]
{a}
Note, that the social choice is given as a list, because it is not necessarily unique. This will become important later on.
> Plurality:
>
> Declare the social choice(s) the alternative(s) with the largest
> number of first-place rankings in the ballot list.
This is the respective implementation:
plurality[ballots_] :=
Module[{}, GatherBy[SortBy[Tally[ballots[[All, 1]]], Last], Last][[-1, All, 1]]]
The social choice is computed like this:
plurality[ballots]
(*{a}*)
> Borda Count
>
> We award points to the n alternatives in a ballot as follows: the
> alternative at the bottom receives zero points; the one next to it
> receives one point and so on up to the alternative on the top of the
> list which receives (n-1) points.
This is the implementation of the social choice function:
bordacount[ballots_, alternatives_] :=
Module[{}, GatherBy[SortBy[Total[Flatten[{Reverse[Range[0, Length[alternatives] - 1]]*Transpose[ballots]}]] /. {Plus -> List, Times -> List},
First], First][[-1, All, 2]]]
which can be applied like so:
bordacount[ballots, alternatives]
(*{a}*)
> Hare System
>
> The procedure is as follows: we delete the alternative(s) that is on
> top of the fewest of the individual preference lists. The resulting
> individual preference lists are at least one shorter than before. We
> then repeat this process; the last alternative(s) is/are the
> winner(s).
Our Wolfram Language is
haresystem[ballots_] :=
Module[{},
Sort[DeleteDuplicates[Flatten[If[Length[#[[-1, 1]]] > 0, #[[-1, 1]], #[[-2, 1]]] &@
NestWhileList[((# //. (# -> Nothing & /@ Complement[alternatives, #[[All, 1]]])) //. (# -> Nothing & /@
GatherBy[SortBy[Tally[#[[All, 1]]], Last], Last][[1, All, 1]])) &, ballots, Length[DeleteDuplicates[Flatten[#, Infinity]]] > 1 &]]]]]
which is evaluated like so:
haresystem[ballots]
(*{a}*)
> Sequential pairwise voting
>
> We start with a fixed order of alternatives {a,b,c,d,..}. The first
> alternative is evaluated against the second in a one-to-one contest.
> The winning alternative (or both if there is a tie) then is compared
> to the third alternative. An alternative is deleted at the end of any
> round if it loses a one-to-one contest.
We will use a new ballot for the evaluation for clarity:
alternatives = {a, b, c, d}
ballots = Table[RandomSample[alternatives, Length[alternatives]], {k, 4}]
(*{{d, b, a, c}, {d, a, c, b}, {d, c, b, a}, {b, d, c, a}}*)
We also need a fixed agenda:
fixedagenda = alternatives[[RandomSample[RandomSample[Range[Length[alternatives]]]]]]
(*{a, b, c, d}*)
The social choice function is then implemented like so:
concorcetindivloser[ballots_List, bin_, acomp_] :=
Module[{},
If[acomp === bin,
"NA", (Which[#1[[1, 2]] === Length[ballots]/2, {"W",
"W"}, #1[[-1, 1, 1]] === bin, "W", True, "L"] &)[
SortBy[Tally[(Select[#1, #1 == acomp || #1 == bin &] &) /@
ballots], Last]]]]
seqpair[ballots_, fixedagenda_] :=
Module[{winners = {fixedagenda[[1]]}},
Do[AppendTo[winners, fixedagenda[[k]]];
winners =
Pick[winners, ! MemberQ[Flatten[#], "L"] & /@
Outer[concorcetindivloser[ballots, #1, #2] &, #, #] &@
winners], {k, 2, Length[fixedagenda]}]; winners]
We can evaluate this like so:
seqpair[ballots, fixedagenda]
(*{b}*)
> Dictatorship
>
> One of the voters is chosen and called "dictator". The alternative on
> top if their individual preference list is the social choice.
We can implement this function like so:
dictatorhip[ballots_, k_] := {ballots[[k, 1]]}
where $k$ is the index of the person who is the "dictator".
dictatorhip[ballots, 3]
(*{d}*)
A closer look at the social choice procedures
----------
All of these social choice functions are implemented in different parts of the world. It turns out that they have the curious habit of not agreeing on the social choice even if the ballots are the same!
Let's suppose we have the following ballots:
ballots = {{a, b, c, d, e}, {a, d, b, e, c}, {a, d, b, e, c}, {c, b, d, e, a}, {c, d, b, a, e}, {b, c, d, a, e}, {e, c, d, b, a}};
So there are 7 voters and the lists are the preference lists of them. Here is another representation:
Transpose@ballots // MatrixForm
![enter image description here][5]
Let's apply Condorcet's method first:
condorcet[ballots, alternatives]
(*{}*)
That means that Condorcet's method does not produce a social choice. This is obviously a critical problem of a social choice function, because it would not be suitable to lead the decision making process to a conclusion.
Let's try the plurality rule:
plurality[ballots]
(*{a}*)
It determines that the social choice is a. So the electorate has decided for alternative a.
Next up: the Borda Count:
bordacount[ballots, alternatives]
(*{b}*)
So according to the Borda Count b is the winner - in spite of the ballots not having changed!
What about the Hare system?
haresystem[ballots]
(*{c}*)
Next up, the sequential voting system. Let's choose the fixed agenda
fixedagenda = {a, b, c, d, e};
We then obtain:
seqpair[ballots, fixedagenda]
(*{d}*)
So under this social choice function d is the winner.
Last the dictatorship. Let's make person 7 the dictator:
dictatorhip[ballots, 7]
(*{e}*)
Now, e is the winner. Curious...
So in this simple case existing social choice procedures would have led to all different alternatives in spite of the ballots being exactly the same. This is a bit frightening because all these systems are actually being used today.
Optimal social choice procedure
----------
The question is whether there is an "optimal" social choice procedure. The answer to that question turns out to be no. First we define the following five desirable properties:
1. Always a winner. The procedure should always produce a winner. We have already seen that for example Condorcet's method does not give a winner for the last example.
2. Condorcet winner criterion. A social choice procedure is said to satisfy the Condorcet winner criterion (CWC) provided that\[LongDash]if there is a Condorcet winner\[LongDash]then it alone is the social choice.
3. Pareto condition. A social choice procedure is pareto if for every pair x and y of alternatives we have: If everyone prefers x to y, then y is not a social choice.
4. Monotonicity. A social choice procedure is monotone if for any x the following holds: If x is the social choice (or tied for such) and someone changes his or her preference list by moving x up one spot (that is, exchanging x's position with that of the alternative immediately above x on his or her list), then x should still be the social choice (or tied for such).
5. Independence of Irrelevant Alternatives. For every pair of alternative x and y we have: If the social choice set includes x but not y, and one or more voters change their preferences, but no one changes his or her mind about whether x is preferred to y or y to x, then the social choice set should not change so as to include y.
These are very (!) desirable properties and reasonable requirements. Unfortunately, the following theorem holds:
**THEOREM.**
There is no social choice procedure for three or more alternatives that satisfies the always-a-winner criterion, independence of irrelevant alternatives, and the Condorcet winner criterion.
There is also a more general theorem by Arrow, that -roughly speaking- that there cannot be a social choice function fulfilling some basic properties.
What happens for larger constituencies?
----------
Let's create a larger set of voters and hence individual preference lists.
alternatives = {a, b, c, d, e};
and
constituency = Table[RandomSample[alternatives], 200];
Condorcet:
condorcet[constituency, alternatives]
(*{}*)
Plurality:
plurality[constituency]
(*{b}*)
Borda count:
bordacount[constituency, alternatives]
(*{e}*)
Hare system:
haresystem[constituency]
(*{d}*)
Sequential pairwise:
fixedagenda = alternatives[[RandomSample[RandomSample[Range[Length[alternatives]]]]]];
(*{e}*)
That is not very encouraging. But perhaps the outcomes depend on the population size?
Monitor[results =
Table[{pop,
Table[constituency = Table[RandomSample[alternatives], pop];
fixedagenda =
alternatives[[
RandomSample[
RandomSample[Range[Length[alternatives]]]]]]; {Length[
DeleteCases[#, {}]], Length /@ #} &@
Union[Sort /@ {condorcet[constituency, alternatives],
plurality[constituency],
bordacount[constituency, alternatives],
haresystem[constituency],
seqpair[constituency, fixedagenda]}], {50}]}, {pop, 10, 500,
10}];, pop]
I have varied the population size of the electorate from 10 to 500 in steps of 10. The variable results looks like this (here for 500 voters):
results[[-1]]
(*{500, {{2, {0, 1, 1}}, {2, {0, 1, 2}}, {3, {0, 1, 1, 2}}, {1, {0,
1}}, {3, {0, 1, 1, 1}}, {2, {0, 1, 1}}, {2, {0, 1, 1}}, {2, {0, 1,
1}}, {3, {0, 1, 2, 2}}, {1, {0, 1}}, {2, {0, 1, 1}}, {2, {0, 1,
1}}, {1, {0, 1}}, {1, {0, 1}}, {1, {0, 1}}, {3, {0, 1, 1,
2}}, {4, {0, 1, 1, 2, 3}}, {1, {0, 1}}, {1, {0, 1}}, {1, {0,
1}}, {1, {0, 1}}, {1, {0, 1}}, {3, {0, 1, 1, 2}}, {1, {0,
1}}, {2, {0, 1, 1}}, {2, {0, 1, 2}}, {2, {0, 1, 1}}, {2, {0, 1,
1}}, {2, {0, 1, 1}}, {1, {0, 1}}, {2, {0, 1, 3}}, {1, {0,
1}}, {3, {0, 1, 1, 1}}, {1, {0, 1}}, {2, {0, 1, 1}}, {2, {0, 1,
1}}, {2, {0, 1, 2}}, {1, {0, 1}}, {3, {0, 1, 1, 1}}, {2, {0, 1,
1}}, {2, {0, 1, 1}}, {3, {0, 1, 1, 2}}, {3, {0, 1, 1, 1}}, {2, {0,
1, 1}}, {4, {0, 1, 1, 1, 2}}, {1, {0, 1}}, {2, {0, 1,
1}}, {2, {0, 1, 1}}, {1, {0, 1}}, {2, {0, 1, 1}}}}*)
The first 500 is the number of voters. Then there are 50 "realisations", i.e. 50 independent elections where voters make random choices. Each of the 50 sublists has a first entry which gives the number of different results using different social choice functions and ignoring empty sets, i.e. "no-winner" scenarios. Let's plot the histogram of the number of different outcomes using the various social choice functions:
Histogram[results[[-1, 2, All, 1]],
AxesLabel -> {"number of different outcomes", "number of elections"},
ImageSize -> Large, LabelStyle -> Directive[Bold, Medium]]
So in most cases the social choice functions give different results, even if there are 500 voters. Then we can count how many winners there are in cases of different results:
results[[-1, 2, All, 2]]
(*{{0, 1, 1}, {0, 1, 2}, {0, 1, 1, 2}, {0, 1}, {0, 1, 1, 1}, {0, 1,
1}, {0, 1, 1}, {0, 1, 1}, {0, 1, 2, 2}, {0, 1}, {0, 1, 1}, {0, 1,
1}, {0, 1}, {0, 1}, {0, 1}, {0, 1, 1, 2}, {0, 1, 1, 2, 3}, {0,
1}, {0, 1}, {0, 1}, {0, 1}, {0, 1}, {0, 1, 1, 2}, {0, 1}, {0, 1,
1}, {0, 1, 2}, {0, 1, 1}, {0, 1, 1}, {0, 1, 1}, {0, 1}, {0, 1,
3}, {0, 1}, {0, 1, 1, 1}, {0, 1}, {0, 1, 1}, {0, 1, 1}, {0, 1,
2}, {0, 1}, {0, 1, 1, 1}, {0, 1, 1}, {0, 1, 1}, {0, 1, 1, 2}, {0, 1,
1, 1}, {0, 1, 1}, {0, 1, 1, 1, 2}, {0, 1}, {0, 1, 1}, {0, 1,
1}, {0, 1}, {0, 1, 1}}*)
So all cases contain cases of "no winner", when there is a zero in the sublist. This comes mostly from Condorcet's method, which often does not give a winner. The ones indicate that in the respective outcomes there was only one winner. A two or three means that the winner was not unique, i.e. a tie. So basically of all the outcomes only the ones lead to a decision. So only
N[Count[#, 1]/Length[#]] &@Flatten[results[[-1, 2, All, 2]]]
(*0.568*)
57% of the cases lead to a unique winner. If we ignore the no-winner scenarios we see that only in
N[Count[#, 1]/Length[#]] &@(Length[#] - 1 & /@ results[[-1, 2, All, 2]])
(*0.34*)
about 34% of the cases the methods agree on the winner.
Let's see how these numbers change for different sizes of electorates. First, we compute the percentage of "unique winner scenarios" for different sizes of the electorate (ignoring no winner scenarios):
ListLinePlot[Table[{results[[k, 1]], N[Count[#, 1]/Length[#]] &@Flatten[results[[k, 2, All, 2]]]}, {k, 1, 50}],
FrameLabel -> {"size of electorate", "percentage unique winner"}, LabelStyle -> Directive[Bold, Medium], ImageSize -> Large,
PlotTheme -> "Marketing"]
![enter image description here][6]
With a bit more CPU time, we can study whether there is a saturation effect for larger population sizes...
Let's look at the agreement of the different social choice procedures:
ListLinePlot[Table[{results[[k, 1]], N[Count[#, 1]/Length[#]] &@(Length[#] - 1 & /@ results[[k, 2, All, 2]])}, {k, 1, 50}],
FrameLabel -> {"size of electorate", "percentage agreement"},
LabelStyle -> Directive[Bold, Medium], ImageSize -> Large, PlotTheme -> "Marketing"]
![enter image description here][7]
So, more often than not, the social choice procedures to not agree on the winner. This might suggest a type of independence of the population size.
Conclusion
----------
Even if the ballots are fixed deciding what the voters meant to say is by no means trivial. "Reading" the voters' minds even if they have spoken is mathematically speaking very problematic. For the case of only two alternatives (Brexit/No-Brexit) and an odd number of voters the thing appears to be easier, but as we will see later, there are many more issues.
**This is not meant to say that we should give up or ignore the outcome of elections.** To maintain order and piece as a society we need to agree on a particular social choice procedure and accept the outcome. We need to take decisions and these decisions have to be based on established rules. The only issue is that sometimes the social choice ("will of the people") depends on the social choice function and not solely on the ballots!
We have a type of "societal contract" to accept the outcome of elections under the rules (social choice function) that is agreed upon before the elections. This does not necessarily mean, however, that politicians can claim that this is the "will of the people"; it is the decision made based on a ballot and an agreed upon social choice procedure.
[1]: http://community.wolfram.com/groups/-/m/t/1222959
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1423.26.23.png&userId=48754
[3]: http://community.wolfram.com/web/bschelter
[4]: https://www.amazon.co.uk/Mathematics-Politics-Strategy-Voting-Power/dp/1441926615
[5]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1422.42.52.png&userId=48754
[6]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1423.46.02.png&userId=48754
[7]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2017-11-1423.47.36.png&userId=48754Marco Thiel2017-11-14T23:53:48ZWhy does the WolframKernel exit on OS X without a trace during Integrate?
http://community.wolfram.com/groups/-/m/t/1222503
I am trying to calculate a quantity from its density in 3D over a rectangular 2D window frame the following way:
mflxx = Integrate[
mi3ret[[1, 1]], {y, -w/2,
w/2}, {z, -(c/2 + zf + d/2), -(c/2 + zf + d/2 + h)}]
where `mi3ret[[1,1]]` is a fairly long expression containing only elementary functions of the `x,y` and `z` variables, and it is the x-component of a 3D vector function. It also contains some constant parameters, like `a,b,c`. `zf,d,h` are additional constants for the definite integral. After a long calculation the `WolframKernel` is killed by the OS without any message or CrashReport. So, after rebooting the machine and running just Mathematica and the Activity Monitor, I made some screenshuts to see, how the memory is used and put the memory related value into lists. See notebook attached, where the 0 minute is really after about one and half hours into the run. The machine is an early 2011 Early MacPro with 64GB memory and a 500GB Flashdrive partitioned into two 250GB partition. So, the questions are:
1. Why the `WolframKernel` is killed without a trace?
2. Can the OS tuned in such a way that `Integrate` can finish its run?
3 Is there a command or function in Mathematica that would alert to the coming
doom and would allow the examination of the status of the machine, including the status of the `WolframKernel`?
4. Is it possible to configure Mathematica to use, for disk based intermediate storage, the partition that have more free space, /the boot drive itself has 150GB, the other partition has 230GB free space/ ?
Thanks ahead,
JánosJanos Lobb2017-11-15T04:29:13Zstrange result in a cubic equition?
http://community.wolfram.com/groups/-/m/t/1222449
Please look at this outcome:
![enter image description here][1]
As you see, all 3 roots are complex numbers. But this equition has a real root at least 1.
This is 0.1736 ... (exactly sin 10 degrees).
![enter image description here][2]
Where is my fault?
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ucuncuDD_forumSoru1.PNG&userId=1222434
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ucuncuDD_forumSoru2.PNG&userId=1222434Metin Guney2017-11-15T09:21:51Z[✓] Get list of industry segments using FinancialData?
http://community.wolfram.com/groups/-/m/t/1222525
In the helpfile I found two examples to get a list of industry-segments:
Take[FinancialData["DrugManufacturers-Major", "Members"], 20]
FinancialData["Publishing-Books", "Members"]
I would like to get a list of companies from different industrial area's. I tried several names like for example `FinancialData["banks", "Members"]` with the same result: Missing["NotAvailable"].
Is there a list of industrie-segments availableMichiel van Mens2017-11-15T08:17:12ZAvoid warning without disabling it for this plot?
http://community.wolfram.com/groups/-/m/t/1222092
Hi,
I am using this line to plot a magnetic field :
ReplaceAll[
crossSectionFieldPlot["\[ScriptCapitalH]",
nqvrbmmf[mm0, a, b, c, x, 0, z][[{1, 3}]] ], {mm0 -> 10^6,
a -> 0.01, b -> 0.01, c -> 0.01}]
`crossSectionFieldPlot` is from the blog of Michael Trott with a small modification. The plot is created at the end, but I am getting a bunch of warnings before, because Mathematica tries to use the `a, b, c` parameters of `nqvrbmmf` in `crossSectionFieldPlot` without doing the numerical replacements first. I tried also this form:
crossSectionFieldPlot["\[ScriptCapitalH]",
nqvrbmmf[mm0, a, b, c, x, 0, z][[{1, 3}]] ] //
ReplaceAll[#, {mm0 -> 10^6, a -> 0.01, b -> 0.01, c -> 0.01}] &
but the warnings are still there. So the real question is, how to make the substitutions with `ReplaceAll` for the parameters of `nqvrbmmf` BEFORE the evaluation of `crossSectionFieldPlot` ? I also tried a few combinations of `Hold` and `ReleaseHold` here and there with no cigar.
Thanks ahead,
JánosJanos Lobb2017-11-15T01:25:47Z[✓] Area under the curve of a Parametric Plot function?
http://community.wolfram.com/groups/-/m/t/1220905
I am looking to find the area under the curve of the a parametric plot function I tried to use a simple example but it's giving me two answers for each function rather than one when I use NIntegrate. Is there another way to get the area under the curve of the parametric plot ?
Thank you
ParametricPlot[{Sin[t], Sin[2 t]}, {t, 0, 1.57 }]
NIntegrate[{Sin[t], Sin[2 t]}, {t, 0, 1.57 }]Joeseph A2017-11-12T20:41:27Z[✓] Find a simple x^n power kind of block in Modelica library?
http://community.wolfram.com/groups/-/m/t/1222299
I purchased Mathematica and system modeler a while ago to learn design with computers...simulation and the like..and when trying to derive the energy of a system I was attempting to simulate, I required from the math block ( I would think at least) the power of an input...which for the life of me I can't find in the program, the documentation or anywhere on the internet....and I ended up making my own component...basically a modified gain, where k=n n being whatever power I desired...but system modeler complains everything time I try to load a simulation with my custom components...but that is actually another problem for another day...
So my question is. Where do I find a simple x^n power kind of block? Surely something like this isn't missing.Mor Bo2017-11-14T23:01:29ZSolve this differential equation?
http://community.wolfram.com/groups/-/m/t/1222403
(Edited to add: I may have solved my problem now. See end of post.)
This does not work (edited to fix a mistake of mine):
DSolve[{
0 == -voltageC0[t] - 2*voltageC0''[t] + 2*voltageC1''[t],
0 == -voltageC1[t] - 2*voltageC1''[t] + 2*voltageC0''[t]
}, voltageC0[t], t]
Mathematica replies:
> DSolve::overdet: There are fewer dependent variables than equations,
> so the system is overdetermined.
I cannot make sense of that response from Mathematica. I see two dependent variables, and I see two equations. Two equals two. What is the meaning of Mathematica's response to my query?
Edited to add: This attempt apparently succeeds:
DSolve[{
0 == -voltageC0[t] - 2*voltageC0''[t] + 2*voltageC1''[t],
0 == -voltageC1[t] - 2*voltageC1''[t] + 2*voltageC0''[t]
}, {voltageC0, voltageC1}, t]
The large constant-numerical-values appearing in the solution do surprise me though.Joe Donaldson2017-11-15T05:23:23Z[✓] Find first local minima?
http://community.wolfram.com/groups/-/m/t/1221485
Dear All,
I have a list as following (for example)
data = {10,8,7,6,5,3,4,5,2,3,2,1,0}
The first local minima is 3.
How can I find this value in Mathematica ?
Thank so much for your help.M.A. Ghorbani2017-11-14T17:35:22ZWolfram Alpha for .NET: open source software library
http://community.wolfram.com/groups/-/m/t/1220925
![Wolfram Alpha][1]
#**Wolfram Alpha .NET**
Hello everyone!
I would like to announce **Wolfram Alpha .NET**
Repository link: https://github.com/xjose97x/WolframAlpha
Wolfram Alpha .NET is an open source software library for interacting with the Wolfram Alpha API on the .NET platform.
After doing some research, I found out that there's no library for Wolfram Alpha for .NET being mantained and up-to-date. The .NET library published on the [Wolfram site][2] has not been updated for ages, and it is written in Visual Basic.
So with the help of [Wolfram Alpha Full Results API documentation][3] and [Wolfram Alpha Webservice API documentation][4] I built a type-safe library to query Wolfram Alpha from .NET.
##**Quick Start**
Create a WolframAlphaService with your APP ID:
WolframAlphaService service = new WolframAlphaService("YOUR APP ID");
Create a request to query with WolframAlphaRequest:
WolframAlphaRequest request = new WolframAlphaRequest
{
Input = "YOUR QUERY"
};
Send the request to WolframAlpha:
WolframAlphaResult result = await service.Compute(request);
WolframAlphaResult is a class that holds the [QueryResult][5]
![QueryResult structure][6]
Some values may or may not be defined in the result, since it depends on the query and the response given by the Wolfram Alpha Webservice API. For instance, there may be cases in which Wolfram Alpha returns or not Assumptions, Tips, Errors, etc.
However, all the properties are defined in the code, and you'll be able to see them when coding (code prediction with Intellisense on VIsual Studio)
And if you'd like to print on the console the Pods with text returned, you could do it this way:
foreach (var pod in result.QueryResult.Pods)
{
if(pod.SubPods != null)
{
Console.WriteLine(pod.Title);
foreach (var subpod in pod.SubPods)
{
Console.WriteLine(" " + subpod.Plaintext);
}
}
}
Which will print the following in the case of querying "Stephen Wolfram":
![Console Example][7]
You can filter and do more complex queries by including other properties on the WolframAlphaRequest object such as the Pod Ids , Units (Metric, non metric), formats, your location, etc. Look at [parameter references][8].
Some work is still left to be done, however I believe in it's current state is usable for most situations.
All suggestions are Welcome.
Hope you enjoy it!
##**Found an issue**
Please report it through [Github issues on the repository][9]
##**Would you like to contribute?**
Contributions are always welcome! Fork the repo and submit a Pull Request
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=1000px-Wolfram_Alpha_logo.svg.png&userId=1151285
[2]: http://products.wolframalpha.com/api/libraries.html "WolframAlpha Libraries"
[3]: https://products.wolframalpha.com/api/documentation/ "Wolfram Alpha Full Results API"
[4]: http://products.wolframalpha.com/docs/WolframAlpha-API-Reference.pdf?_ga=2.22650683.1895728587.1510530683-479065163.1490235393 "Wolfram Alpha Webservices API"
[5]: https://products.wolframalpha.com/api/documentation/#result-queryresult "QueryResult"
[6]: http://community.wolfram.com//c/portal/getImageAttachment?filename=quickwatch.png&userId=1151285
[7]: http://community.wolfram.com//c/portal/getImageAttachment?filename=wolframconsole.png&userId=1151285
[8]: https://products.wolframalpha.com/api/documentation/#parameter-reference "Parameter references"
[9]: https://github.com/xjose97x/WolframAlpha/issuesJose Escudero2017-11-13T01:17:33ZDo Dynamic locators work on the cloud?
http://community.wolfram.com/groups/-/m/t/1180509
In Stephen Wolfram's book (Elementary Introduction...) he says "...in a web page you'll be able to use active sliders... though they'll run slower than if they were directly on your computer" (1st ed., p.218). Fair enough, but I wonder if other objects such as dynamic locators actually work on the cloud at all. I just deployed a notebook with a dynamic locator which should move when dragged, but it simply doesn't seem to work at all. Sliders work, although somewhat slow, as expected.Tomas Garza2017-09-09T18:23:42Z[✓] Solve symbolic system of differential and algebric equations?
http://community.wolfram.com/groups/-/m/t/1221443
Hello everyone, I tried to solve a symbolic system of differential and algebric equations between (0,x) with the following code:
DSolve[{(Qd Cd)'[x] == kd (Ci[x] - Cd[x]), (Qd)'[x] ==
ko (Cd[x] - Ci[x]), Qa (Ca)'[x] == ka Ca[x],
ka Ca[x] == kd (Ci[x] - Cd[x])}, {Qd, Cd, Ca}, x]
where Qa, ko, ka, kd are positive constants. The code does not work. I expect the solution:
![enter image description here][1]
Thank you very much for your time.
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=sde.png&userId=818155Gennaro Arguzzi2017-11-14T16:07:32Z[✓] Plot gradient of a function of a variable?
http://community.wolfram.com/groups/-/m/t/1220498
Hello everyone, I'd like to plot the gradient of a function of a variable. Before I hope that the derivative is the component of the gradient, that is a scalar, instead the gradient is a vector. For example, for the function f(x)=x^2 and f'(x)=2x, the gradient should be the plot with green arrows:
![enter image description here][1]
I tried to do it with the following statement:
VectorPlot[{2 x, 0}, {x, -3, 3}, {y, 0, 0.00001}]
Is it correct?
When I try to plot f(x), f'(x) and gradient, I get a strange plot because maybe the range {y, 0, 0.00001} in VectorPlot does not allow to show me the range I set:
Show[VectorPlot[{2 x, 0}, {x, 0, 2.5}, {y, 0, 0.00001}],
Plot[x^2, {x, 0, 2.5}, PlotRange -> {{0, 2.5}, {0, 6}}],
Plot[2 x, {x, 0, 2.5}, PlotRange -> {{0, 2.5}, {0, 6}},
PlotStyle -> Red]]
Thank you so much for your time.
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=4576Funzione,derivata,gradienteinunadimensione.png&userId=818155Gennaro Arguzzi2017-11-12T15:54:26ZPass a variable to Wolfram code when using Cloud Deploy?
http://community.wolfram.com/groups/-/m/t/1220970
We're new to Wolfram but in a very short time using the Web Development Platform have been able to develop a solution that presents business stats from system events logged in a Data Drop databin. This databin collects events and "tags" the system from which it came by adding a system ID (sID) as one of the variables logged. Our development solution hard codes the sID in the initialization section. What we would like to do is to pass the sID into the code as a variable in the Cloud Deploy URL which in turn we can pull out of the URL and use to "dynamically" set sID. The APIFunction seems to head in the right direction but I've not been able to figure out how to encapsulate all our code (initialization > creation of datasets > computation of datasets > presentation of stats) in the APIFunction body. In short, we're stuck so am hoping the Community can give some guidance.
THANKS!Randy Schultz2017-11-13T14:17:34ZSolve a system of DAEs with discrete conditions using NDSolve?
http://community.wolfram.com/groups/-/m/t/1221798
I have also asked [this question here in SO][2].
I'm trying to solve a system of DAEs with discrete conditions:
muk = 0.2;
mus = 0.3;
m1 = 1;
m2 = 2;
m3 = 3;
Fn12 = 3;
Fn23 = 2;
minvel = 0.1;
F1[x_] := 2*Sin[5*x];
F2[x_] := 2*Sin[7*x];
Fs12[x_] := (m2*F1[x] - m1*F2[x])/(m1 + m2);
Off[NDSolve::pdord]
s = NDSolve[{m1*x1''[t] == F1[t] - Ff12[t], x1'[0] == 0, x1[0] == 0,
m2*x2''[t] == F2[t] + Ff12[t], x2'[0] == 0, x2[0] == 0,
Ff12[t] ==
If[Abs[x1''[t] - x2''[t]] < 0.1 && Abs[Fs12[t]] < mus*Fn12 ,
Fs12[t], muk*Fn12*Sign[x1''[t] - x2''[t]]]}, {x1, x2, Ff12}, {t,
10}]
However when solving I get two weird errors:
> NDSolve::tddisc
> NDSolve cannot do a discontinuity replacement for event surfaces that depend only on time
> NDSolve::nderr
> Error test failure at t==...; unable to continue
![enter image description here][1]
which searching on google does not offer that much of the results!
I have found some relevant posts and documentations. It seems that I have to use a helper function or something like that using Piecewise and/or WhenEvent functions but I can't get my head around it!
I would appreciate if you could explain why this error happens and how I can modify my code to avoid it?
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=Untitled.png&userId=1014408
[2]: https://mathematica.stackexchange.com/questions/159894/ndsolve-cannot-do-a-discontinuity-replacement-for-event-surfaces-that-depend-onlFoad Sojoodi Farimani2017-11-14T13:47:13ZAvoid HTML Export error in 11.2?
http://community.wolfram.com/groups/-/m/t/1220050
The following piece of code worked fine in Mathematica 11.1:
notesgrid = Text[Grid[{{ Hyperlink["pdf link 1", "notes-1.pdf"]}}]]
Export[FileNameJoin[{NotebookDirectory[], "notes.html"}], notesgrid];
But in 11.2 it fails to produce the hyperlink in the html source code (it doesn't create the <area> tags), though the link does appear in the Mathematica output cell.
Is this a known problem? Is there a workaround (other than going back to 11.1)?Andrew2017-11-10T23:31:44ZSoccer Field Theory
http://community.wolfram.com/groups/-/m/t/1221624
Can there be computational soccer? This fall I was trying to explain to some kids that the most dangerous place for attackers to have the ball is right in front of the goal where they can get off a good shot. Then it occurred to me the second most dangerous place is where someone can pass it to the attacker, the third region would be where a pass can be made to the second region, etc.. (The goal is on the left.)
![Partitioned field for kids][1]
Here I took the dimensions of a under-8 field, being 30 yards by 40 yards with a 12 yard goal. With the assumption of a reliable pass of 5 yards, the field gets partitioned into many regions, possibly explaining some of the differences with adult soccer (longer passes can be considered reliable).
At first I tried to use Regions, e.g. RegionDistance, but I wasn't able to get that to work (Does anyone know how to do that?) and then tried this solution that splits the field into a bunch of points, makes a Graph object, then the Graph functionality splits the field up.
points = N[
Flatten[Table[{i, j}, {i, 0, 40, 1/2}, {j, 0, 30, 1/2}], 1]];
edges = Flatten[
Table[If[EuclideanDistance[points[[i]], points[[j]]] < 5,
If[points[[i, 1]] == points[[j, 1]], {i -> j, j -> i}, j -> i],
Nothing], {i, Length[points]}, {j, i + 1, Length[points]}]];
graph = Graph[Join[edges, Table[i -> "Goal", {i, 20, 42}]]];
Graphics[Map[{RandomColor[], Point[points[[#]]]} &,
Complement @@@ Partition[Table[VertexList[NeighborhoodGraph[graph, "Goal", d]], {d, 10, 1, -1}], 2, 1]]]
Then I changed it so the "most dangerous" region has the requirement that the angle of the goal is at least 1/2 radians (if the goal's perspective is too narrow it is hard to get past the goalie).
![Partitions taking into account the angle][2]
These pictures are not too profound, but maybe someone can do a simpler or more aesthetic solution.
One can think of this as being a physics-inspired solution (field theory of soccer), where every possible pass on the field is taken into consideration. But maybe there are some classical mathematical solutions?
Speaking of physics, what would be the equipotentials be if the net were given a charge (e.g. the two nets could be capacitors) Normally the net is irrelevant but if it had a charge how could that affect a charged ball trying to get into the net)?
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=soccer-field-30-40.jpg&userId=23275
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=soccer-field-30-40-B.jpg&userId=23275Todd Rowland2017-11-14T03:31:44ZAutomate data file imports to use Classify?
http://community.wolfram.com/groups/-/m/t/1219623
Hello, I am trying to use the default data files for machine learning. Often, these come as CSV or just data files that are text. For example, this data file has 768 records:
data = ReadList[
"https://archive.ics.uci.edu/ml/machine-learning-databases/pima-\
indians-diabetes/pima-indians-diabetes.data", Record, 768];
The column names represent:
col_names = {"pregnant", "glucose", "bp", "skin", "insulin", "bmi", "pedigree", "age", "label"};
I would like to be able to easily partition that into something that can directly be fed into Classify, for example:
mytrain ={{6,148,72,35,0,33.6,0.627,50}->1,{1,85,66,29,0,26.6,0.351,31}->0,{8,183,64,0,0,23.3,0.672,32}->1,{1,89,66,23,94,28.1,0.167,21}->0,{0,137,40,35,168,43.1,2.288,33}->1,{5,116,74,0,0,25.6,0.201,30}->0,{3,78,50,32,88,31.0,0.248,26}->1,{10,115,0,0,0,35.3,0.134,29}->0,{2,197,70,45,543,30.5,0.158,53}->1,{8,125,96,0,0,0.0,0.232,54}->1};
Is there a simple way to tell Mathematica to partition these 768 records and put them in the form given above {{...} -> label}, as shown in a generic way? That is, I can say split the data into a training and testing data set where I can select the number of columns, which is the label and how many items I want in the training and testing sets in the format needed by Mathematica?
I tried messing with all of the standard commands, but I must be missing some fundamental thing about the representation of data.
For what it is worth, I am trying to duplicate this example:
http://www.ritchieng.com/machine-learning-evaluate-classification-model
including all of the classifier results, confusion matrix, metrics and ROC curves.
Thank you for any insights.Q Q2017-11-09T17:58:27Z[✓] Get an accurate smooth boundary of the mesh generated by ToElementMesh?
http://community.wolfram.com/groups/-/m/t/1221340
I try to generate a mesh over a region, which has a wavy boundary at its bottom and needs very fine mesh around the bottom.
However, the generated mesh boundary is not as smooth as the specified region. The region is
![enter image description here][1]
The generated mesh is
![enter image description here][2]
If we zone-in we will find the bottom boundary is not the one as specified, see
![enter image description here][3]
The bottom looks very bad.
I further try to generate the boundary first. Here is what I found.
![enter image description here][4]
The boundary is not generated correctly.
Anyone know how to generate the correct meshed boundary?
The minimum work code is as follows.
Needs["NDSolve`FEM`"];
width = 1;
heigth = 0.25;
radius = 10;
ydatum = 0.006;
Aw = 5 10^-3;
\[Lambda]w = 0.1;
\[ScriptCapitalR] =
ImplicitRegion[
Abs[x] <= width/2 && y <= heigth + ydatum &&
y >= x^2/(2 radius) + Aw (1 - Cos[(2 \[Pi] x)/\[Lambda]w]) +
ydatum, {x, y}];
RegionPlot[\[ScriptCapitalR], FrameTicks -> None,
AspectRatio -> Automatic, ImageSize -> Large,
PlotRange -> {{-0.35, 0.35}, {0.005, 0.256}}]
bmesh = ToBoundaryMesh[\[ScriptCapitalR],
"BoundaryMeshGenerator" -> "Continuation", AccuracyGoal -> 2]
bmesh["Wireframe"]
meshrefine =
Function[{vertices, area},
Block[{x, y}, {x, y} = Mean[vertices];
If[ydatum < y < ydatum + 0.025, area > 3.0*10^-7, area > 0.0002]]];
mesh1 = ToElementMesh[\[ScriptCapitalR], "MeshOrder" -> 1,
MaxCellMeasure -> {"Length" -> 0.01},
MeshRefinementFunction -> meshrefine]
mesh1["Wireframe"]
Show[mesh1["Wireframe"], PlotRange -> {{-0.05, 0.05}, {0.005, 0.04}},
ImageSize -> 800]
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=MQSUg.png&userId=1221320
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=XGrfq.png&userId=1221320
[3]: http://community.wolfram.com//c/portal/getImageAttachment?filename=cogOC.png&userId=1221320
[4]: http://community.wolfram.com//c/portal/getImageAttachment?filename=1.jpg&userId=1221320Wilhelm Deng2017-11-13T22:34:49ZDeploy 3D interactivity to the Wolfram cloud?
http://community.wolfram.com/groups/-/m/t/1176101
Hi,
I have a website that involves a lot of (static) 3D graphics I've created in Mathematica. Is there a way to integrate 3D interactivity with the graphics with the Wolfram cloud? I would prefer to not use a Manipulate to rotate the graphics but rather just use the mouse. Is that possible? Would someone know of a tutorial on line I could read and learn how to do this if so? For example, suppose I had the plot Sin[x y] shown in my website. Could I then have a cloud link that would allow the user to then rotate the plot with the mouse?
Thanks,
DominicDominic Milioto2017-09-03T14:33:51ZSpecify a general rule, so that mathematica always evaluate it?
http://community.wolfram.com/groups/-/m/t/1221102
I want to specify a set of some general mathematical rules regarding probability theory to solve equations with "expectation" and "variance" for random variables. Therefore I want to "teach" mathematica to evaluate the expression
Integrate[p[x], {x, -Infinity, Infinity}] -> 1
always to "1". p[x] should be any arbitrary "Probability Density Function" of "x" with the result, whenever mathematica's evaluation finds the integral in an expression, it should replace it by "1"
I tried this with
Simplify[Integrate[p[x], {x, -Infinity, Infinity}] /. Integrate[p[x], {x, -Infinity, Infinity}] :> 1]
and similar expressions and rules, but when I put into the next cell:
Integrate[p[x], {x, -Infinity, Infinity}]
the output is always the Integral itself, but not the expected value of "1".
My final goal is if I specify:
expectation[x_] := Integrate[x*p[x], {x, -Infinity, Infinity}]
expectation[z_] := Integrate[z*p[x], {x, -Infinity, Infinity}] /; FreeQ[z, x] := z /; FreeQ[z, x]
that mathematica recognize "z" as a constant, independant from x, get it out of the Integral and evaluates the remaining Integral to "1" and the final result as "z"
How can I solve such a problem ?
Thank you for your support.
Regards
Uweuwe moehring2017-11-13T11:01:49Z[✓] Increment in multiple sum indices?
http://community.wolfram.com/groups/-/m/t/1221132
Hello,
I am trying to write nested sums of the following form:
![enter image description here][1]
But i need the index j to run from 0 with an increment as follows:
![enter image description here][2]
any suggestions? Thanks
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=2631question.jpg&userId=1221116
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=answer.jpg&userId=1221116Shahzeb Kamal2017-11-13T11:54:17ZKnowledge base for my Voice Assistant
http://community.wolfram.com/groups/-/m/t/1220764
Hello everyone. I'm Mukul Sharma from India, I'm an engineering student and as a part of my interest and academics I'm making a project. The project is voice based Assistant much like Siri or google now. I developed it using python. Its a modular assistant with User Interface, speech to text, text to speech etc. But an assistant needs to be smart, it must have a knowledge base from which it can answer the questions of its user. I was lagging this part. Since google or another platform don't give any google answer api or direct link to their knowledge base, I was loosing hope for my project. But then I find Wolfram Alpha, and its knowledge base surprised me, because its knowledge base is much like an assistant. For e.g. if you ask an assistant, "What is laplace of sine of t?" then it should give an answer, where as google gives a link which is favorable for mobile or pc but not for voice based assistant, I find the concept of wolfram astonishing. But there was limit of 2000/month. And since my project is currently in testing so I need to check it over various commands and everyone knows that testing takes much more resources than actual product. So 2000/moth were too short for me. Then I contacted the wolfram and explained my problem, I got a quick and helpful response from Ish. The wolframalpha as a company is very generous to give me quota of 20000/month for my research project on Voice based Assistant. Because of this quota I can work on my project and enhance its capabilities. I sincerely thanks Ish as well for helping me getting this quota. Also if anyone from the wolfram community want to help me develop an open source Voice based Assistant, you are always welcome
my mail id: mukulsharma.0462@gmail.com
Again thanks to Ish and Wolframalpha for helping me out in my research project.Mukul Sharma2017-11-12T19:16:41ZPlot vector functions in different coordinate systems?
http://community.wolfram.com/groups/-/m/t/995028
Hello to all:
I teach physics at a community college in Arizona. Currently I am working on documents to assist students in visualization of Electrostatic and Magnetic fields. Almost all require either cylindrical or spherical coordinates. My question is: Given a field expressed in cylindrical coordinates, how do you generate a vector plot of the field in that coordinate system?
Please note, that I have already found a method to convert the field from cylindrical to cartesian coordinates, and the VectorPlot function works just fine once I convert it, but I would like some options so that I do not need to convert the field but rather just plot it directly. This would also be helpful in the event that I want to visualize fields in other orthogonal coordinate systems e.g. toroidal coordinates.
Thank you all for your consideration and responses.
Chris Ubing
Sierra Vista, AzChristopher Ubing2017-01-14T20:23:51ZLost a Notebook with 11.0.1. How to get it again?
http://community.wolfram.com/groups/-/m/t/973618
I use Wolfram Programming Lab (Standard License). Normally from the Desktop version on an up-to-date Win10 PC. Last Thursday I updated to version 11.0.1 from 11.0.0. This worked with no problem.
I was developing a pretty large and tricky notebook (.nb) for two weeks. It was stored within the Wolfram cloud and is still there. I worked with it last Friday after the update and saved it to the cloud. No problem.
Since Saturday I cannot reopen that notebook. The ProgLab-Desktop says: *"There was a syntax error in the file being read. Do you want to open it as plain text? ... If you are able to fix the error, save the file and open it again"*.
Let aside that my notebook had no syntax error when last saved on Friday evening, it's somewhat ridiculous that a program with a syntax error cannot be reopened.
When I answer YES to open the file as plain text, I get another error message: *"There was a syntax error on line ... The error was: <lots of zeros>"*. Then the file opens empty as white space. No notebook, no plain text. Just one header line *"Notebook[{},..."*.
When I try to open that notebook directly from the website (https://lab.wolframcloud.com/app/. Not the desktop version), it opens completely empty with no error message at all.
I'm afraid, I lost that program and have no idea, why. It is still in the cloud, 1MB large, saved last Friday evening, which is correct.
**Does anyone have an idea how I could regain that notebook-file?**Werner Geiger2016-12-03T15:00:35ZCompute the composition of two permutations?
http://community.wolfram.com/groups/-/m/t/1219357
{2,4,1,3} and {3,1,2,4} are two permutations of {1,2,3,4}.How to find the composition of these two permutations which is {1,2,4,3} (composition from right to left)?Thanks.jagannath debata2017-11-09T12:07:01Z[✓] Stop re-evaluating an assignment like x=x+1 in Manipulate?
http://community.wolfram.com/groups/-/m/t/1220479
Can some shed some light on the following behaviour of manipulate:
This works like expected:
Manipulate[
x = x0;
x
, {x0, 0, 1}]
However, if there is an assignment like x= x+1, where the same variable is on both side of the "=", this seems to be interpreted as a recursion and Manipulate does not stop evaluating:
Manipulate[
x = x0;
x = x + 1;
x
, {x0, 0, 1}]Daniel Huber2017-11-12T12:03:22ZJigsaw Puzzle
http://community.wolfram.com/groups/-/m/t/1214169
![enter image description here][1]
Dear all, from the resemblance of a Voronoi mesh to a jigsaw puzzle I came to the idea for the following little program I want to share. The essential function is
(* in: points p1, p2;
out: BSplineCurve = jigsaw side if distance > minLength; *)
jigsawSide[minLength_][pts : {p1_, p2_}] := Module[{m, u, o, vx, vy, n, dist, r, c, angle0, cPts},
dist = EuclideanDistance @@ pts;
If[dist < minLength, Return[Line[pts]]];
(* avoid borders: *)
If[Times @@ (p2 - p1) == 0, Return[Line[pts]]];
m = Mean[pts];
{u, o} = SortBy[pts, Last]; (* lower/upper point *)
{vx, vy} = o - u;
n = {vy, -vx}; (* normal vector *)
r = .15 dist; (* radius *)
c = m + n/4.; (* center *)
angle0 = Sign[Last[n]] VectorAngle[{1, 0}, n];
(* points on circle: *)
cPts = c + r {Cos[angle0 + #], Sin[angle0 + #]} & /@ (60 \[Degree] {-2, -1, 0, 1, 2});
Return[BSplineCurve[{u, m, Sequence @@ cPts, m, o}]]
]
which connects two points with a `BSplineCurve` having the typical elementary shape of a jigsaw puzzle. If the distance is too short then the connection becomes a straight line. The same happens if the points share the same x- or y-coordinate to exclude the jigsaws borders. Here is a simple test of the function:
![enter image description here][2]
Anything else is straightforward:
- start with "randomized" lattice points;
- from these a Voronoi mesh is created;
- extract its polygons;
- convert the polygon sides into the new (puzzle) shape;
- build new polygons out of these sides;
- apply a texture.
The result is a bunch of jigsaw pieces one can play with:
![enter image description here][3]
I was impressed by the consistent behavior of `Texture`. The whole (short) code is attached.
Best regards -- Henrik
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=9927ezgif.com-optimize.gif&userId=11733
[2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=PieceSide.gif&userId=32203
[3]: http://community.wolfram.com//c/portal/getImageAttachment?filename=JigsawsExample.png&userId=32203Henrik Schachner2017-11-04T19:25:59ZPlot multiple functions?
http://community.wolfram.com/groups/-/m/t/1195801
hi ,
when i tried to solve these eqns to give me function of anther variable ....it gives me so many eqns and i cant know which the right ones so i couldnt plot them
i want to plot w3 , w4 with respect to varible theta2 (i want all varibles in output to be with respect to theta2}
i will attach the code programming
r1 = 600;
r2 = 200;
r3 = 700;
r4 = 900;
(* \[Theta]2 is NOT constant !..*)
\[Alpha]2 = 0;
\[Omega]2 = 12.568;
eq1 = -r1 + r2 Cos[\[Theta]2 ] + r3 Cos[\[Theta]3 ] +
r4 Cos[\[Theta]4 ] ;
eq2 = r2 Sin[\[Theta]2 ] + r3 Sin[\[Theta]3 ] + r4 Sin[\[Theta]4 ] ;
m = Map[{\[Theta]3 , \[Theta]4} /. # &, {ToRules[
N[Reduce[{eq1 == 0 && eq2 == 0} , {\[Theta]3, \[Theta]4}] /. {C[
1] -> 0 , C[2] -> 0}]]}]/Degree;
Plot[m, {\[Theta]2, 0, 2 Pi}]
eq3 = -r2 \[Omega]2 *Sin[\[Theta]2 Degree] -
r3 \[Omega]3 Sin[\[Theta]3 Degree] -
r4 \[Omega]4 Sin[\[Theta]4 Degree];
eq4 = r2 \[Omega]2 Cos[\[Theta]2 Degree] +
r3 \[Omega]3 Cos[\[Theta]3 Degree] +
r4 \[Omega]4 Cos[\[Theta]4 Degree];
q = Map[{\[Omega]3 , \[Omega]4} /. # &, {ToRules[
N[Reduce[{eq3 == 0 && eq4 == 0} , {\[Omega]3 , \[Omega]4}]]]}];
Plot[q, {\[Theta]2, 0, 2 Pi}]Ahmed Khodari2017-10-01T17:14:27ZHow can I use Manipulate with a NIntegrate defined function?
http://community.wolfram.com/groups/-/m/t/1216627
Hi, I'm trying to model a spiral galaxy using some density distributions and display them with a 2D density plot. The functions are integrated along a line of sight in order to reduce the 3 variables functions to 2 variables function. In order to make a rotating plot I'm trying to use Manipulate. Here it is my code, which gives me as output only a static image that doesn't rotate moving the slider.
The code is this:
LogarithmicScaling[x_, min_, max_] := Log[x/min]/Log[max/min]
f[x_?NumericQ, y_?NumericQ, t_?NumericQ] :=
NIntegrate[
2.872416767*10^3*Exp[(-Sqrt[x^2 + y^2])/2.676]*Exp[(-Abs[z] + 1- Cos[2*(ArcTan[y/x] - t) + (2/(Tan[7*Pi/90]))*Log[Sqrt[x^2 + y^2]/4.9]])] +7.013941065*10^5*Exp[-Sqrt[x^2 + y^2 + z^2]/0.09866] + (7.321354473)/(1 + (Sqrt[x^2 + y^2 + z^2]/3.936)^2)^(5/2), {z, -Infinity, +Infinity}]
plotter[min_, max_, NumberOfTicks_] :=
Manipulate[DensityPlot[f[x, y, t], {x, -25, 25}, {y, -25, 25},
PlotRange -> Full, ColorFunctionScaling -> False,
ColorFunction -> (ColorData["SunsetColors"][
LogarithmicScaling[#, min, max]] &), PlotPoints -> 50,
PlotLegends ->
BarLegend[{ColorData["SunsetColors"], {0, 1}},
LegendMarkerSize -> 370,
Ticks -> ({LogarithmicScaling[#, min, max],
ScientificForm[#, 1]} & /@ (min (max/min)^
Range[0, 1, 1/NumberOfTicks]))]], {t, 0, 100},
AnimationRunning -> False, SynchronousUpdating -> False ]
plotter[10^1, 10^5, 4]
The static image which has to rotate is shown in the attachment. If I plot the function fixing t with different values, it actually rotates, but the manipulate function seems to not work at all. Any idea?Eliseo Pavone2017-11-06T20:03:46Z[✓] Add plus 1 to the {i_,i_} elements in a list?
http://community.wolfram.com/groups/-/m/t/1187440
I have a list of lists of numbers, for example:
{{1,1,1,1}, {1,1,1,1},{1,1,1,1},{1,1,1,1}}
The length of the list is the same length of each sublist.
What I want to achieve is to add plus 1 to the {i,i} elements without using For cycle.
Given the list above as an input, I need a result like this:
{{2,1,1,1}, {1,2,1,1},{1,1,2,1},{1,1,1,2}}Ana Reyna2017-09-19T02:54:55ZCreating Star Wars Kylo Ren voice in one line of code
http://community.wolfram.com/groups/-/m/t/1219764
*MODERATOR NOTE: for true Star Wars fans this post has a related Wolfram Cloud App, which you can access by clicking on the image below. Read the full post below to understand how the app works. May the Force be with you.*
[![enter image description here][1]][9]
----------
Kylo Ren voice in [Star Wars The Force Awakens][2] is very cool. When I watched the movie in 2015, one of the first things that came up to my mind was how to do such voice in Mathematica. At the time Mathematica capabilities to manipulate sounds were very simplistic, and was not possible to do such thing.
I'm far far way to be a sound expert, but I tried do something like this:
file = Import["https://s3-sa-east-1.amazonaws.com/rmurta/murta-audio.wav"];
audioOrg = Audio[file];
audioKylo = AudioPitchShift[audioOrg, 0.9];
audioKylo = AudioFrequencyShift[audioKylo,-200]//AudioAmplify[#, 4]&
- Original Murta's record: [Murta original][3]
- And here is the result: [Murta as Kylo][4]
[![Kylo Voice][5]][6]
[youtube link for Kylo][7]
See [original post in Stack Exchange][8], where I ask for improvement in the sound hack.
After that, why not create a cloud app for that?!
This is amazing about Mathematica, with one line of code you can create a App, and everybody can play with It!
CloudDeploy[FormFunction[{"sound"->"Sound"},
AudioAmplify[AudioFrequencyShift[AudioPitchShift[#sound,0.9],-200],4]&],
"kylo-voice-by-murta",Permissions->"Public"]
Here is the link, so you can try it: [kyle-voice-by-murta][9].
Record your sound and speak like Kylo!
[1]: http://community.wolfram.com//c/portal/getImageAttachment?filename=ScreenShot2017-11-14at1.40.15PM2.png&userId=11733
[2]: https://en.wikipedia.org/wiki/Star_Wars:_The_Force_Awakens
[3]: https://s3-sa-east-1.amazonaws.com/rmurta/murta-audio.wav
[4]: https://s3-sa-east-1.amazonaws.com/rmurta/murta-kylo-audio.wav
[5]: http://community.wolfram.com//c/portal/getImageAttachment?filename=kylo-voice2.png&userId=11733
[6]: https://www.youtube.com/watch?v=zy-wqB4cbT8&feature=youtu.be&t=49s
[7]: https://www.youtube.com/watch?v=zy-wqB4cbT8&feature=youtu.be&t=49s
[8]: https://mathematica.stackexchange.com/questions/159744
[9]: https://www.wolframcloud.com/objects/murta/kylo-voice-by-murtaRodrigo Murta2017-11-11T13:06:38ZWhich function to use for this equation?
http://community.wolfram.com/groups/-/m/t/1220169
y = xhello hello2017-11-11T21:00:13Z