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[?] Import and Plot a (5 x a) Matrix from a csv file in Mathematica?

Epsilon Tau
Posted 9 years ago

Hey everyone,

In a practica I collected Data from an oscilloscope. This data is saved in .csv files (an example is in the attachment).

Now I have to plot and fit this data. The main problem is, that I don't even get the data into the right format to plot it. Right now I have this code:

datag1 = Import[
  "C:\\Users\\tobia\\OneDrive\\Grundpraktikum \
1\\Experimente\\4_Harmonsicher Oszillator\\Graph & \
Calculation\\T0027.CSV", "CSV"]

l = Length[datag1]

datag3 = Take[Take [datag1, -l + 16], l - 17]

So now I have a seperated List of all the data points. The next step is, to seperate the matrix to have 5 data lists for the 5 variables, so I can plot and fit them individually. I tried the following things:

Delete[datag3, {All, 2}]

Well this works if i use a specific number instead of All, so I tried to solve the problem with a for-loop.

For[i = 1, i <= Length[datag3] , i++, Delete[datag3, {i, 2}]]

Here datag3 didn't change at all. I think that I somehow have to define a new list, which gets edited but my experience in Mathematica is really limited.

So I decided to use a matrix instead of a list. To be honest, I do not know if there is a major difference between those two in Mathematica, but I decided to give it a try.

matrixfull = MatrixForm[datag3]

Then I used the Transpose command and tryed different things, with the help of Wolfram Doc, but none of them worked. I know that I am kind of a Mathematica noob, but learning everything by yourself is pretty hard. So can you guys help me out? How would you solve this problem?

Thanks, Tobias

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POSTED BY: Epsilon Tau
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Epsilon Tau
Epsilon Tau
Posted 9 years ago

Wow. A big thanks to both of you, this is more helpful that I expected. You saved my weekend guys! :)
POSTED BY: Epsilon Tau

This was my approach.

Import data:

data = Import["C:\\Users\\bgood_000\\Downloads\\T0027.csv"];

and then examine (David Keith's answer above does this much better)

In[42]:= data[[1 ;; 100]]

Out[42]= {{"Model", "DPO2002B"}, {"Firmware Version", 
  1.52}, {""}, {"Point Format", "Y", "", "", ""}, {"Horizontal Units",
   "S", "", "", ""}, {"Horizontal Scale", 4, "", "", 
  ""}, {"Sample Interval", 0.00768049, "", "", 
  ""}, {"Filter Frequency", 7.*10^7, "", "", ""}, {"Record Length", 
  5189, "", "", ""}, {"Gating", "0.0% to 100.0%", "", 
  "0.0% to 100.0%", ""}, {"Probe Attenuation", 10, "", 10, 
  ""}, {"Vertical Units", "V", "", "V", ""}, {"Vertical Offset", 0, 
  "", 0, ""}, {"Vertical Scale", 10, "", 2, ""}, {"Label", "", "", "",
   ""}, {"TIME", "CH1", "CH1 Peak Detect", "CH2", 
  "CH2 Peak Detect"}, {-20., -7.4, -7.8, 
  0.04, -0.12}, {-19.992, -7.4, -7, -0.04, 
  0.12}, {-19.985, -7.4, -7.8, -0.04, -0.2}, {-19.977, -7.4, -7, \
-0.12, 0.04}, {-19.969, -7.4, -7.8, -0.12, -0.28}, {-19.962, -7.4, \
-7, -0.2, -0.04}, {-19.954, -7.4, -7.8, -0.2, -0.36}, {-19.946, -7.4, \
-6.6, -0.2, -0.12}, {-19.939, -7.4, -7.8, -0.2, -0.44}, {-19.931, \
-7.4, -6.6, -0.28, -0.2}, {-19.923, -7.4, -7.8, -0.36, -0.52}, \
{-19.916, -7, -6.6, -0.36, -0.28}, {-19.908, -7, -7.4, -0.44, -0.6}, \
{-19.9, -6.6, -6.2, -0.44, -0.28}, {-19.892, -7, -7.4, -0.44, -0.6}, \
{-19.885, -6.6, -6.2, -0.52, -0.36}, {-19.877, -6.6, -7, -0.52, \
-0.68}, {-19.869, -6.6, -5.8, -0.52, -0.44}, {-19.862, -6.2, -6.6, \
-0.6, -0.76}, {-19.854, -5.8, -5.4, -0.6, -0.52}, {-19.846, -5.8, \
-6.2, -0.6, -0.84}, {-19.839, -5.8, -5, -0.6, -0.6}, {-19.831, -5.4, \
-5.8, -0.68, -0.84}, {-19.823, -5, -4.6, -0.76, -0.6}, {-19.816, -5, \
-5.4, -0.76, -0.92}, {-19.808, -4.6, -4.2, -0.84, -0.68}, {-19.8, \
-4.6, -5, -0.84, -0.92}, {-19.793, -4.2, -3.4, -0.84, -0.76}, \
{-19.785, -3.8, -4.6, -0.84, -1}, {-19.777, -3.8, -3, -0.92, -0.76}, \
{-19.77, -3.4, -3.8, -0.92, -1}, {-19.762, -3, -2.2, -0.92, -0.84}, \
{-19.754, -2.6, -3.4, -0.92, -1.08}, {-19.747, -2.6, -1.8, -1, \
-0.84}, {-19.739, -2.2, -2.6, -1, -1.08}, {-19.731, -2.2, -1, -1, \
-0.84}, {-19.724, -1.4, -2.2, -1, -1.08}, {-19.716, -1.4, -0.6, -1, \
-0.84}, {-19.708, -1, -1.4, -1, -1.08}, {-19.7, -0.6, 
  0.2, -0.92, -0.92}, {-19.693, -0.2, -1, -1, -1.08}, {-19.685, -0.2, 
  1, -1, -0.84}, {-19.677, 0.2, -0.2, -0.92, -1.08}, {-19.67, 0.6, 
  1.4, -1, -0.84}, {-19.662, 1, 0.2, -0.92, -1.08}, {-19.654, 1, 
  2.2, -0.92, -0.84}, {-19.647, 1.8, 1, -0.92, -1}, {-19.639, 1.8, 
  2.6, -0.92, -0.84}, {-19.631, 2.2, 1.4, -0.84, -1}, {-19.624, 2.2, 
  3, -0.92, -0.76}, {-19.616, 2.6, 2.2, -0.84, -0.92}, {-19.608, 3, 
  3.8, -0.84, -0.76}, {-19.601, 3, 2.6, -0.76, -0.92}, {-19.593, 3.4, 
  4.2, -0.76, -0.68}, {-19.585, 3.8, 3, -0.76, -0.84}, {-19.578, 3.8, 
  4.6, -0.76, -0.6}, {-19.57, 4.2, 3.4, -0.68, -0.84}, {-19.562, 4.2, 
  5, -0.76, -0.52}, {-19.555, 4.6, 4.2, -0.68, -0.76}, {-19.547, 5, 
  5.4, -0.6, -0.52}, {-19.539, 5.4, 4.6, -0.52, -0.68}, {-19.531, 5.4,
   6.2, -0.52, -0.44}, {-19.524, 5.4, 5, -0.52, -0.6}, {-19.516, 5.4, 
  6.2, -0.52, -0.36}, {-19.508, 5.8, 5.4, -0.44, -0.52}, {-19.501, 
  6.2, 6.6, -0.44, -0.28}, {-19.493, 6.2, 
  5.8, -0.36, -0.52}, {-19.485, 6.2, 7, -0.36, -0.2}, {-19.478, 6.6, 
  5.8, -0.28, -0.44}, {-19.47, 6.6, 7.4, -0.28, -0.2}, {-19.462, 7, 
  6.2, -0.28, -0.36}, {-19.455, 7, 7.4, -0.28, -0.12}, {-19.447, 7, 
  6.6, -0.2, -0.28}, {-19.439, 7.4, 7.8, -0.2, -0.04}, {-19.432, 7.4, 
  6.6, -0.12, -0.2}, {-19.424, 7.4, 7.8, -0.12, 0.04}, {-19.416, 7.4, 
  6.6, -0.04, -0.12}, {-19.409, 7.4, 7.8, -0.04, 0.12}, {-19.401, 7.4,
   7, 0.04, -0.04}, {-19.393, 7.4, 7.8, 0.04, 0.2}, {-19.386, 7.4, 7, 
  0.12, -0.04}, {-19.378, 7.4, 7.8, 0.12, 0.28}, {-19.37, 7.4, 6.6, 
  0.12, 0.04}, {-19.363, 7.4, 7.8, 0.12, 0.28}}

So there's a header in position 16

In[48]:= data[[16]]

Out[48]= {"TIME", "CH1", "CH1 Peak Detect", "CH2", "CH2 Peak Detect"}

For some reason the last element is empty so I'll pick out everything after the header up to the penultimate element. In[77]:= plotData = data[[17 ;; -2]];

From the header I know the positions of time and voltages (CH1, CH2)

In[94]:= time = plotData[[All, 1]];
ch1 = plotData[[All, 2]];
ch2 = plotData[[All, 4]];

Thread the timebase into each extracted channel amplitude list.

dataset1 = Thread[{time, ch1}];
dataset2 = Thread[{time, ch2}];

And plot

In[99]:= ListLinePlot[{
  dataset1, dataset2
  },
 PlotRange -> All,
 PlotLegends -> {"CH1", "CH2"}
 ]

enter image description here

We can obtain a coarse fit of CH1 by first looking at the peaks 

ListPlot[
 FindPeaks[TimeSeriesResample[TimeSeries[dataset1]]],
 PlotRange -> Full
 ]

enter image description here

Lets extract the upper component of the signal

fittingData = FindPeaks[TimeSeriesResample[TimeSeries[dataset1]]];
upper = Select[fittingData["Path"], #[[2]] > 0 &];

And examine 

ListPlot[upper, Joined -> False]

enter image description here

Find a nonlinear model for the data, $$a \exp{(-bx)} $$ is a good start

nlm = NonlinearModelFit[upper, a*Exp[-b*x], {a, b}, x];

Check nlm and show atop the original plot

Show[{
  Plot[nlm[x], {x, -20, 20}, PlotStyle -> {Dashed, Thick, Blue}, 
   PlotLegends -> nlm],
  ListLinePlot[{
    dataset1, dataset2
    },
   PlotRange -> All,
   PlotLegends -> {"CH1", "CH2"}
   ]
  }, PlotRange -> All]

enter image description here

Repeat for CH2 and refine model if necessary.

Best Regards,

Ben
POSTED BY: Benjamin Goodman
David Keith
David Keith
Posted 9 years ago

Once you Import the data, it helps to use TableForm to look at it. Then you can use the various list manipulation functions to get it into the needed form. Please see the attached notebook. enter image description here

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POSTED BY: David Keith
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