f[t_, n_] := -t^n {Cos@t Sin@t^2, Sin@t Cos@t^2};
ParametricPlot[
 Evaluate[f[t, #] & /@ Range[0, 1, 0.1]], {t, 24 \[Pi], 48 \[Pi]}, 
 Axes -> False, PlotStyle -> Thick]

Hi Abrita,

During the Tuesday webinar someone asked if there is a way to tell if Dataset operators are ascending or descending. There are undocumented functions AscendingQ and DescendingQ in the Dataset package that do this. See this post for details.

Dataset`AscendingQ /@ {Total, Select, All, Key["a"]}
(* {True, True, False, False} *)

Hello all!

My favorite Wolfram Language function is Manipulate because it is simply one of the best ways to show young people how patterns develop and change.

This code is inspired by John. H. Conway (1937-2020), Richard K. Guy (1916-2020) in their Book of Numbers (Springer-Verlag 1996, page 31, Figure 2.10).

ENJOY!

Manipulate[Multicolumn[show[n], columns, Appearance -> "Horizontal"],

 {{columns, 10}, 5, 25, 1}, {{n, 25, "Numbers to display:"}, 5, 1000, 
  1}, {show, {redDots -> "Dots", redSquares -> "Numbers"}},

 LabelStyle -> {14, FontFamily -> "Times"},
 FrameLabel -> {"", "", 
   Column[{Style["What Shapes Do The Red Figures Make?", Bold, 18],
     Style["(a.k.a. Residue Classes for Kids)", Gray]}, 
    Alignment -> Center], ""},

 Initialization :> {
   tinyCircRed = 
    Graphics[{Darker@Red, Disk[{0, 0}, .01]}, ImageSize -> 5],
   tinyCircGray = 
    Graphics[{Lighter@RGBColor[.9, .9, .9], Disk[{0, 0}, .01]}, 
     ImageSize -> 5],

   redSquares[max_] := Table[
     If[IntegerQ[Sqrt[x]] == True, 
      Style[x, Darker@Red, 16, Bold, FontFamily -> "Times"], 
      Style[x, Lighter@Gray]], {x, 1, max, 1}],

   redDots[max_] := Table[
     If[IntegerQ[Sqrt[x]] == True, tinyCircRed, tinyCircGray], {x, 0, 
      max, 1}]}]

What shall I do if I didn't receive the link for the exercises yesterday?

I had to try a lot of correct solutions, before I was able to find an accepted solution for 1.8.

One issue with 1.8 is the definition of "the unit cube". As of my knowledge a unit cube is simply a cube with unit edge length. This definition does not specify a position of "the unit cube". Wolfram Language does have a geometric region function named Cube, where "Cube[]" is defined to be a unit cube centered at the origin. But this seems not to be accepted in 1.8, which seems to assume, that "the unit cube" is centered at {0.5,0.5,0.5}.

Secondly the obvious solution for the Graphics3D primitive list would be the color primitive followed by a sequence of spheres. As the Sphere function does allow to represent a collection of spheres, by specifying a list of center points as its first argument, the simplest solution would be a single color followed by a single Sphere call with a list of 100 center points. Again, both of this seems not to be, what would be accepted as a solution in 1.8. A far less optimal solution finally worked for me. Specifying a list of pairs as primitives in Graphics3D, where each pair contains a single color and a single sphere.

I still did not find any accepted solution for 1.4, 1.13 and 1.18. Additionally the expected output shown in 1.18 does not seem to be correct. At least for my interpretation of the question. Last in the list of the expected outcome is Cheyenne (Wyoming), which should then be the closest capital to Washington DC. I am not living in the states, but as of my knowledge this is obviously not correct.

Hints for solutions: Again these are hinting at one way to solve these problems. If you have a different solution producing the same expected output, please email us (wolfram-u@wolfram.com) your entire exercise notebook with solutions.

• Problem 1.4: RandomChoice will give you a random letter. Other WL functions to consider are Riffle to mix up consonants and vowels, StringJoin to join them, and Table to do the whole process 5 times
• Problem 1.5: There might have been an issue initially but it was fixed right away. The correct solution should be accepted now.
• Problem 1.7: A Panel with its Background set should be mapped over the letters (in upper case) of Russian Alphabet
• Problem 1.8: Sphere[p,r] represents a sphere of radius r centered at the point p. We know r is to be 0.05 and p can be created out of a triplet of RandomReal numbers {x,y,z} less than 1 (because they have to be inside the unit cube). Use Table to create a 100 of these.
• Problem 1.11: Yes this is from the documentation - Neat Examples.
• Problem 1.13: WordList[] should provide the list of words. StringTake can be used on a list of strings - so it can be used on WordList[]. Counts and TakeLargest should do the rest.
• Problem 1.18: The confusion might have been due to the wrong screenshot for the expected output. This has been updated.

Excellent. Thanks for sharing!

Thanks, Abrita,

This has been a BLAST!!! :-)

Thanks, Valeriu.

On Wednesday, I did not get a link to the exercises.

Same, I also have issues with 1.4, 1.8, 1.13, 1.18. Moreover, if I try to introduce unnecessary variables to store intermediate results or start scoping these variables by using Block, With or Module without changing the output, the previously correct result starts getting recognized as incorrect.

Hello All,

Thanks for commenting on the issues. We're working on them.

• Problem 1.11: GenomeData does seem to be running into some issues on the cloud. However the the auto-grader should accept the solution even if the cell throws error on evaluation.

• Problem 1.18: The expected out is as follows (this was fixed on the cloud but in some cases the update is not showing up when you are working on your local copy)

I'll add a few more hints for the problems that seem to be having issues with accepting solutions. As many of you have pointed out TMTOWTDI :) (there's more than one way to do it - more so in the Wolfram Language). We're continuing to work on the autograder to ensure all viable solutions are accepted. If you continue to face issues, feel free to download the exercise notebook, complete your solutions and send to wolfram-u@wolfram.com.

Thanks for your patience.

Please feel free to email wolfram-u@wolfram.com with your solutions.

End-of-study-group open challenge: To all the enthusiastic study group participants ... post a snippet of code using your favorite Wolfram Language function--may be something you learned in one of the study group sessions.

Feel free to "Like" posts by fellow study group participants and we will declare the most liked post, at our last session, on Friday.

Abrita, I haven't received the link to the exercises that were mentioned in the webinar earlier today.If that's because you haven't sent it out yet that's fine. Regards, Rajeev

Thanks.

I am puzzled by the following:

Why are the two blanks interpreted as the same?

Thank you. It takes some getting used to. Does

work as expected because there is no way to evaluate Blank[]^Blank[] even if the blanks are the same? Here is another curious example;

Why does this not pick up e-2f?

Thank you I asked this during the session.

Since I haven't been receiving the reminder email (at all), could you post it here as well? or at least post that they have been sent...

Absolutely!

Sorry, misunderstood the problem 1.15.

Hello Juergen,

I am also from Germany. Did you know, that you can work around the issues publishing Mathematica code or notebooks to an international community by setting the language to English in the interface tab of the Mathematica preferences dialog? This is easy to toggle without changing any language settings of the OS. You'll just have to restart the MMA frontend. After publishing, you can easily switch back to your preferred language, if you want to.

It seems that the verification of the exercise solutions has some issues. Not every valid solution is accepted. As of 1.13, I also was not able to find an accepted solution. I would suspect, that there might be no solution that would be accepted at all.

Question to all: Did anyone find an accepted solution to 1.4, 1.13 or 1.18? I finally gave up on those leaving my not accepted solutions in place.

For those still struggling with 1.8 you might want to check my hints on an accepted solution for 1.8 from my post from yesterday. I am just giving hints on what the verification wants to see, not on the task in solving the exercise.

If anyone did find a solution to 1.4, 1.13 or 1.18, I would appreciate some hints from the community. You should not post a solution, but some insight on what the verification wants to see would be helpful. I don't think this will be considered as cheating. @Wolfram: Could you confirm this or add some clarification on those exercises.

Hi Muhammad, We tried to keep the solutions as simple one-liners.You will not have to use Module or Block.

I have sent the file with all exercises solved!

Did you mean Friday May 29 ?

May 26-27 Challenge: From EIWL ...

Find a dataset of the 5 largest observed altitudes in the Fireballs & Bolides dataset.

Extra credit:

Plot the nearest cities for the 10 entries with largest altitudes in the Fireballs & Bolides dataset, labeling each city.

Paul, I'd like to troubleshoot your email issue with you directly. I will send an email to you shortly.

Hello everyone. I am a novice to physics, but I am quite interested in the potentially new way of interpreting physics, offering my contribution where I can and wondering if this is the right place to start. Could someone please help?

Thanks Abrita. Will have look.

Right you are! As long as your code is producing the expected output - it should be accepted by the autograder. If you do run into any issues, please report to wolfram-u@wolfram.com

Hi @David Schulz, I am sorry for the miscommunication. There are two different levels of certification associated with this study group. The first is a certificate of program completion, and that requires the four quizzes. The other is Level I certification in programming fundamentals, and that requires the exercise set. The previous (April) study group did not offer Level I certification, so that has caused a little confusion.

I still did not get a link to the exercises

@David Schulz, those emails are being sent this morning. Yours should have arrived by now. Let me know, please.

I received the email with the link. Thank you!

My solution for 1.5 is not accepted even though it generates the expected output.

In Problem 1.15, the expected output is incorrect:

The correct output should be 654421

I accidentally typed * in the solution cell and it is converted to item cell and now I can't work on it. Can someone please tell me how to reset the test?

Well done, from my point of view. My code is less elegant but provides the same output. The funny thing in my case is that my code runs very well on Mathematica V12.1, but it produces hard errors on the test page.

I'm also seeing an error on the webpage with the Genome data, although it works fine in Mathematica 12.1 desktop. The exercise 1.11 is taken directly from the GenomeData help page (in the "Neat Examples" section). Oddly, the example code generates an error on the exercises web page, but is accepted as a "correct" response.

this should work ok now.

Hi Valeriu, The certificates of completions have been going out this week. Please email us if you haven't received yours.

[WSG20] Programming Fundamentals Week 4

Thank you, Abrita! I have received it yesterday!

For 1.8, I used RandomPoint for the center of the sphere rather than a triplet of random real numbers. My code produces the expected output but is not accepted. What is your definition of the unit cube?

1.15 My code produces the correct (expected) output and uses the suggested functions, but doesn't check. I've tried it with both Integer and String outputs. ???

Hi Muhammad, Click inside the cell and hit the shortcut keys to change to "Input" style Cmd 9 on a Mac or Alt 9 on Windows. Let us know if that does not work.

The correct radius is 0.05.

What gets into Graphics3D should look like

{{Orange, Sphere[{x1,y1,z1}, 0.05]}, ... {Orange, Sphere[{xn, yn, zn}, 0.05]}}

where all xi, yi, zi are in the interval [0, 1]. You might remove the call to Graphics3D from your code to check it.

Correct depth of the list is also important. {{{Orange, Sphere[{x1,y1,z1},0.05]},...}} will also not be accepted.