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[WSS21] Improving the question-answer database of EIWL book

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On improving the question-answer database of Elementary Introduction to Wolfram Language

Tuseeta Banerjee

Wolfram Research

Elementary Introduction to Wolfram Language (EIWL) is perhaps one of the best, concise and one-stop and free introductions to the Wolfram Language. It not only introduces Wolfram Language, but can also be considered a tool to improve one’s existing coding skills. Any individual, with a programming or non-programming background can read this book for free, and get at par with programming in Wolfram Language. The chapters of this book do an excellent job of capturing the richness and variety of Wolfram Language and the interface of submitting answers with automatic grading is also quite attractive. Students at WSS over the past few years solve various problems from EIWL before moving on to Wolfram Challenges questions. However, the answers to the problems in the book are not unique, and that issue is already mentioned in the book. A part of this project is to create alternate versions of answers to challenges that do not currently exist in the database of answers, so that they may be helpful in improving the learning experience of thousands of students online who use this book judiciously to improve their coding skills.
A second aspect of the project is to identify questions that have ambiguity in them and may be subject to multiple interpretations from the student. From an educational stand point, the question in turn does not become a metric of the knowledge of the student, but the ability of the student to actually “guess” what the question-maker asks for. A part of this project also addresses some of these questions.

Section 1: Database questions

This section deals with all the internal database questions, which might be updated regularly and hence the answers do not match to the existing answers.

1. Count the number of words in WordList[] that start with “q”

I am not sure if the WordList[] is updated which results in the incorrectness of the following two answers. However, I verified the solution with two very different approaches with String (and they both confirmed same answers).

In[]:=

(Counts@StringTake[ToLowerCase@WordList[],1])["q"]

Out[]=

194

In[]:=

Length@Select[WordList[],StringMatchQ[#,"q"~~___]&]

Out[]=

194

2. Make a line plot of the lengths of the first 1000 words in WordList[]

In[]:=

ListLinePlot@StringLength@(WordList[][[1;;1000]])

Out[]=

Plausible reason: WordList has been updated.

3. Plot together the historical frequencies of the words “science” and “technology

I have no idea if the WordFrequencyData for these words got updated, but they don’t seem to match. I even added PlotLegends to match the Expected Output, but it still did not work.

In[]:=

DateListPlot[{WordFrequencyData["technology","TimeSeries"],WordFrequencyData["science","TimeSeries"]}]

Out[]=

4. Make a labeled bar chart of the number of times each possible first letter occurs in words from WordList[].

In[]:=

BarChart[Counts@StringTake[ToLowerCase@WordList[],1],ChartLabelsAlphabet[]]

Out[]=

5. Make an association giving the 5 most common first letters of words in WordList[] and their counts.

In[]:=

(ReverseSort@Counts@StringTake[ToLowerCase@WordList[],1])[[;;5]]

Out[]=

s4502,c3694,p3168,d2436,a2397

6. Find the 10 most common words in ExampleData[{“Text”,”AliceInWonderland”}]

In[]:=

Keys@((ReverseSort@Counts@TextWords@ToLowerCase@ExampleData[{"Text","AliceInWonderland"}])[[1;;10]])

Out[]=

{the,and,a,to,she,of,it,was,in,alice}

7. Find the longest 10 words in WordList[].

In[]:=

(ReverseSort@AssociationThread[WordList[]->StringLength/@WordList[]])[[1;;10]]

Out[]=

electroencephalographic23,electroencephalograph21,uncharacteristically20,magnetohydrodynamics20,internationalization20,electroencephalogram20,counterrevolutionary20,compartmentalization20,buckminsterfullerene20,straightforwardness19

8. Correct the program Counts[StringTake[#,2]&/@WordList[]]

In[]:=

Counts[StringTake[#,2]&/@Select[WordList[],StringLength[#]>2&]]

Section 2: Ambiguous questions

1. Create a sound from the letters in CABBAGE, each playing for 0.3 seconds sounding like a guitar

This question is ambiguous and I kept guessing what I need to do with the letters of the word “CABBAGE”, LetterNumber made most sense, but apparently it is not what the question wants.

In[]:=

Sound[Table[SoundNote[n,0.3,"Guitar"],{n,LetterNumber["cabbage"]}]]

Out[]=

2. Display 100 polygons with side length 10 and opacity [0.5] and random choices of colors, sides between 3 and 8, and integer coordinates up to 100

The confusion to this question is about the words side length, are they the radius of the polygon or the side of the polygon, because although they are related, they are not the same.

In[]:=

Graphics@Table[{RandomColor[],Opacity[0.5],RegularPolygon[{RandomInteger[100],RandomInteger[100]},10,RandomInteger[{3,8}]]},{i,100}]

Out[]=

3. Make a histogram of sentence length in the Wikipedia article on computers.

This is an ambiguous question: Is Sentence Length = # of words? # of characters? From the histogram of expected output it seems character Length. I tried both none of them were accepted.

In[]:=

Histogram@(Length/@(TextWords/@TextCases[WikipediaData["computers"],"Sentence"]))

Out[]=

In[]:=

Histogram[StringLength/@TextCases[WikipediaData["computers"],"Sentence"]]

Out[]=

Section 3: Entity questions

1. Get an image of an elephant

A simple answer from making a query to W|A resulted in the image, which seems correct, but is unacceptable by the database.

In[]:=

African bush elephant

SPECIES SPECIFICATION



image



Out[]=

2. Compute the height of the Empire State Building divided by the height of the Great Pyramid

A simple answer from making a query to W|A resulted in the image, which seems correct, but is unacceptable by the database. There are multiple pyramids, so specifying which one of them would help clear the ambiguity here.

In[]:=

Empire State Building

BUILDING



total height



Egyptian Pyramids of Giza

BUILDINGS



total height



Out[]=

{2.74101,21.7714,12.5743,12.7,12.8716,2.80147,19.05,5.77273}

Entity["Building","EmpireStateBuilding::h583b"][EntityProperty["Building","Height"]]/EntityClass["Building","PyramidsGiza"][EntityProperty["Building","Height"]]

3. Find the dominant colors of an image collage of the flag images of all countries in Europe

I seem to not be getting the correct answers for any of the ImageCollage-s on the images of flags of countries in Europe, if I do either the W|A query input or the hard-coded Entity way of programming. Not sure where the answer database fails to match mine. I have not compared the answers to the already existing answers (because that is not how a student is expected to approach the problem). I believe it is in the way the question is structured. My guess is that it wants us to query for countries in European Union, and not the countries in continent Europe, but there remains an ambiguity in the question.

In[]:=

DominantColors@ImageCollage@EntityValue

Europe

GEOGRAPHIC REGION



countries

,

flag



In[]:=

DominantColors@ImageCollage@EntityValue[Entity["GeographicRegion","Europe"][EntityProperty["GeographicRegion","Countries"]],EntityProperty["Country","Flag"]]

Out[]=





4. Make Pie Chart of the GDP of countries of Europe

I seem to not be getting the correct answers for any of the countries in Europe questions. My guess is that it wants us to query for countries in European Union, and not the countries in continent Europe, but there remains an ambiguity in the question. However, the pie chart looks exactly the same as the one given in Expected Answers, and thus I ran out of guesses as well!

In[]:=

PieChart@EntityValue

Europe

GEOGRAPHIC REGION



countries

,

GDP

nominal



PieChart@EntityValue[Entity["GeographicRegion","Europe"][EntityProperty["GeographicRegion","Countries"]],EntityProperty["Country","GDP",{"CurrencyUnit""CurrentUSDollar"}]]

Out[]=

5. Make ImageCollage of the flags of all countries in Europe. using the “FlagImage” property

In[]:=

ImageCollage@EntityValue[Entity["GeographicRegion","Europe"][EntityProperty["GeographicRegion","Countries"]],EntityProperty["Country","FlagImage"]]

Out[]=

6. Get a list of distances to each planet using “DistanceFromEarth” property and convert all the results to light minutes

Not sure if the data is updated as a result of which the answers do not match.

In[]:=

UnitConvert

planets

PLANETS



distance from Earth

,"LightMinutes"

Out[]=



8.06881

light minutes

11.9968

light minutes

20.5786

light minutes

35.3044

light minutes

74.9533

light minutes

167.707

light minutes

245.125

light minutes



7. Binarize each flag of Europe and make an image collage of the result.

In[]:=

ImageCollageBinarize/@EntityValue

Europe

GEOGRAPHIC REGION



countries

,

flag



Out[]=

8. Make a pie chart of the GDP’s of the countries in the G5, labeling each wedge.

In[]:=

PieChartThread

Group of 5

COUNTRIES



GDP

nominal

EntityList@

Group of 5

COUNTRIES

["Name"]

Out[]=

9. Make a pie chart of the GDP’s of the countries in the G5, giving a legend for each wedge.

In[]:=

PieChartQuantityMagnitude

Group of 5

COUNTRIES

["Population"],ChartLegendsEntityList@

Group of 5

COUNTRIES

["Name"]

Out[]=

10. Make a word cloud of countries in Central America with the names of countries are proportional to the lengths of the Wikipedia article about them.

In[]:=

names=

Central America

COUNTRIES

["Name"];WordCloud@AssociationThread[names->StringLength@DeleteStopwords@(WikipediaData[#]&/@names)]

Out[]=

11. Find universities that can be referred to as “U of X” where x is any letter of the alphabet.

They are the same answers.

In[]:=

Cases[Interpreter["University"][StringJoin["U of ",#]&/@ToUpperCase@Alphabet[]],_Entity]

Out[]=



University of Birjand

University of Chicago

The University of Edinburgh

University of Georgia

University of Houston

University of Illinois at Urbana-Champaign

University of Lethbridge

University of Michigan-Ann Arbor

University of Phoenix-Online Campus

University of Regina

University of Saskatchewan

University of Toronto



Section 4: Manipulate questions

11. Make a Manipulate to rotate an image of a cat between 0° and 180°

This has been observed in many Manipulate question. Many a times, the step size is not mentioned, as a result of which there can be ambiguities, do you want continuous step sizes or in some size differences. This is just an example

In[]:=

ManipulateRotate

,i,{i,0°,180°}

Out[]=

Section 5: Apparently correct answers

1. Find the distance from 0 latitude 0 longitude to Eiffel Tower

This answer is actually correct and matches the answer provided but the answer is not accepted.

GeoDistanceGeoPosition

Eiffel Tower

BUILDING

,GeoPosition[{0,0}]

2.Make a 12x12 multiplication table with white type on black background

This grid did not actually evaluate properly in the cloud and the answer did not match the existing answers.

In[]:=

Grid[Table[i*j,{i,12},{j,12}],BackgroundBlack,ItemStyleWhite]

Out[]=

3. Flatten to generate a table from 1 to 50 where even numbers are colored red.

This look right, and use the functions also mentioned in the question

In[]:=

Flatten@Table[{i,Style[2*i,Red]},{i,25}]

Out[]=

{1,2,2,4,3,6,4,8,5,10,6,12,7,14,8,16,9,18,10,20,11,22,12,24,13,26,14,28,15,30,16,32,17,34,18,36,19,38,20,40,21,42,22,44,23,46,24,48,25,50}

4. Make a 3D plot of heights generated from Mod[i,j] with i and j going upto 100

This plot look very similar to the Expected Output but it was not accepted.

In[]:=

ListPlot3D@Flatten[Table[{i,j,Mod[i,j]},{i,100},{j,100}],{1,2}]

Out[]=

5. Generate a 3D list plot using the image data from a binarized size-200 letter “W” as heights.

This plot look very similar to the Expected Output but it was not accepted.

In[]:=

ListPlot3D@ImageData@Binarize@Rasterize@Style["W",200]

Out[]=

6. Make a graphics of 1000-step 2D random walk which starts at {0,0}, and in which at each step a pair of random numbers between -1 and 1 are added to the coordinates

The output look similar to the Expected Output.

In[]:=

Graphics@Line@NestList[#+{RandomReal[{-1,1}],RandomReal[{-1,1}]}&,{0,0},1000]

Out[]=

7. Make a graphics of 1000 - step 3 D random walk which starts at {0, 0,0}, and in which at each step a pair of random numbers between - 1 and 1 are added to the coordinates

In[]:=

Graphics3D@Line@NestList[#+{RandomReal[{-1,1}],RandomReal[{-1,1}],RandomReal[{-1,1}]}&,{0,0,0},1000]

Out[]=

8. Make a LinePlot that takes lengths of Roman numerals up to 100 that PlotRange would be sufficient for all numerals up to 1000

This answer actually matches if I explicitly say Range {0,12}, although we do not need to go upto 12, and PlotRange -> All/Automatic were sufficient.

In[]:=

ListLinePlot[StringLength/@RomanNumeral@Range[100],PlotRange{Full,{0,12}}]

Out[]=

9. Start with a size-50 “A”, then make a list of nestedly applying frame and random rotations 5 times

I am not sure about why not a single approach was accepted. I tried various approaches and the output look similar to the Expected Output

In[]:=

NestList[Framed@Rotate[#,RandomInteger[180]Degree]&,Style["A",50],5]

In[]:=

NestList[Framed@Rotate[#,RandomInteger[180]Degree]&,Text@Style["A",50],5]

In[]:=

NestList[Framed@Rotate[#,RandomInteger[180]Degree]&,Rasterize@Text@Style["A",50],5]

10. Generate a graph with 200 connections, each between nodes with numbers chosen randomly between 0 and 100

This answer is very similar to a previously accepted answer and indeed we make 200 connections randomly between nodes numbered from 0 to 100

In[]:=

Graph@Flatten@Table[{iRandomInteger[{0,100}],iRandomInteger[{0,100}]},{i,0,100}]

Out[]=

11. Generate a plot that shows communities in a random graph with nodes numbered between 0 and 100, and 200 connections

In[]:=

CommunityGraphPlot[Graph@Flatten@Table[{i->RandomInteger[{0,100}],i->RandomInteger[{0,100}]},{i,1,100}]]

Out[]=

12. Generate a graph obtained by nestedly finding bordering countries starting from the United States, and going 4 iterations.

In[]:=

NestGraph[#[EntityProperty["Country","BorderingCountries"]]&,Entity["Country","UnitedStates"],4]

Out[]=

13. Make a list of all the different strings that can be obtained by permuting the characters in “hello”

In[]:=

StringJoin/@Permutations[Characters["hello"]]

Out[]=

{hello,helol,heoll,hlelo,hleol,hlleo,hlloe,hloel,hlole,hoell,holel,holle,ehllo,ehlol,eholl,elhlo,elhol,ellho,elloh,elohl,elolh,eohll,eolhl,eollh,lhelo,lheol,lhleo,lhloe,lhoel,lhole,lehlo,lehol,lelho,leloh,leohl,leolh,llheo,llhoe,lleho,lleoh,llohe,lloeh,lohel,lohle,loehl,loelh,lolhe,loleh,ohell,ohlel,ohlle,oehll,oelhl,oellh,olhel,olhle,olehl,olelh,ollhe,olleh}

14. Make an array plot from the numbers of the letters in the first 1000 characters in the Wikipedia article on “Computers”, with 30 letters per row.

In[]:=

ArrayPlot@Partition[LetterNumber/@Characters@StringTake[WikipediaData["computers"],1000],30]

Out[]=

15. Riffle periods in the string “UNCLE” to make “U.N.C.L.E.”

In[]:=

StringRiffle[Characters@"UNCLE","."]

Out[]=

U.N.C.L.E

16. Make a list of array plots, each 50 rows high and with image size 50, of successive possible 8-tuples of 0 and 1.

In[]:=

ImageResize[#,50]&/@(ArrayPlot/@Partition[Tuples[{0,1},8],50])

Out[]=

17. Generate 1000 random sequences of 4 letters, and make a list of ones that appear in WordList[]

In[]:=

Intersection[StringJoin/@Table[RandomSample[Alphabet[],4],{i,1000}],WordList[]]

Out[]=

{best,brow,gain,glow,have,plod}

18. Make a word cloud of country names in the Wikipedia article on “gunpowder”.

In[]:=

WordCloud@DeleteDuplicates@TextCases[WikipediaData["gunpowder"],"Country"]

Out[]=

19. Find all nouns in “She sells seashells by the sea shore”

In[]:=

TextCases["She sells seashells by the sea shore","Noun"]

Out[]=

{seashells,sea,shore}

20. Use TextCases to find the number of nouns, verbs and adjectives in the first 1000 characters of the Wikipedia article on computers.

In[]:=

Values@(Length/@TextCases[StringTake[WikipediaData["computers"],1000],{"Noun","Verb","Adjective"}])

Out[]=

{54,25,19}

56. Generate 10 random strings made of 5 letters, in which consonants (non-vowels) alternate with vowels (aeiou).

In[]:=

Table[StringJoin@Riffle[RandomChoice[Complement[Alphabet[],{"a","e","i","o","u"}],3],RandomChoice[{"a","e","i","o","u"},2]],10]

Out[]=

{cujol,culin,nulay,lihut,cadab,cipit,kuxuj,hahiq,wuxed,yaviy}

21. Define a function evenodd that gives Black if its argument is even and white otherwise, but gives red, if the argument is o.

In[]:=

evenodd[x_]:=Which[x0,Red,EvenQ[x],Black,True,White]

22. Find the 5 longest integer names for integers up to 100.

In[]:=

(ReverseSort@AssociationThread[IntegerName[Range[100]]->StringLength/@IntegerName[Range[100]]])[[1;;5]]

Out[]=

seventy-eight13,seventy-seven13,seventy-three13,ninety-eight12,ninety-seven12

23. find the 5 English names for integers up to 100 that have the largest number of “e”s in them.

In[]:=

(Keys@ReverseSort@AssociationThread[IntegerName[Range[100]]->(Length/@StringPosition[IntegerName[Range[100]],"e"])])[[1;;5]]

Out[]=

{seventy-seven,seventy-three,seventeen,ninety-seven,ninety-three}

Section 6: Time and day related questions

There is a common pattern for these questions, they are hard to verify with the expected output, and follow a pattern for next few days (some mention today, some not, in that case the length of the output had to be compared), and some discrepancies are just hard to verify.

1. Compute the number of days since January 1 1900

This answer is hard to verify with the Expected Answer (the Expected Output for such questions need to be updated on a daily basis). Also, the queries from W|A actually match the code as well. Not sure why it is not accepted.

In[]:=

Quantity[DayCount[DateObject[{1900,1,1}],Today],"days"]

Out[]=

44385

days

In[]:=

Out[]=

44385

days

2. Find the length of daylight today by subtracting today’s sunrise form today’s sunset

I have tried this question in different ways, however, I never got it to accept.

In[]:=

Sunset[Today]-Sunrise[Today]

Out[]=

889

min

In[]:=

UnitConvert[Sunset[Today]-Sunrise[Today],MixedRadix["Hours","Minutes"]]

Out[]=

min

In[]:=

Sun

STAR



daily time above horizon



Out[]=

48.

min

In[]:=

Sunset[Here,Today]-Sunrise[Here,Today]

Out[]=

889

min

In[]:=

UnitConvert[Sunset[Here,Today]-Sunrise[Here,Today],MixedRadix["Hours","Minutes"]]

Out[]=

min

3. Generate list of icons for the moon phases from today until 10 days from now

Many of these questions refer to from today until 10 days from now, and often require which days to be included. This particular answer never got accepted and I did not expect the Expected Output to match either

In[]:=

MoonPhase[#,"Icon"]&/@DateRange[DayPlus[Today,1],DayPlus[Today,10]]

Out[]=

4. How many weeks have elapsed since January 1, 1900?

Again the coded interpretation match the W|A query but none match the answer in the database. Not sure if it a Round/Floor error, which seem to be the case. There is some ambiguity here.

In[]:=

Quantity[Round[N@DayCount[DateObject[{1900,1,1}],Today]/7],"week"]

Out[]=

6341

In[]:=

Out[]=

6341.

5. Show in a column the times of the sunrise for the next 10 days starting today

Many of these questions refer to from today until n days from today and often require which days to be included. I often match the number of outputs in the Expected answer but this case it never got accepted.

In[]:=

Column@Table[Sunrise[Here,DayPlus[Today,n]],{n,0,9,1}]

Out[]=

Minute: Sat 10 Jul 2021 05:33GMT-5

Minute: Sun 11 Jul 2021 05:34GMT-5

Minute: Mon 12 Jul 2021 05:34GMT-5

Minute: Tue 13 Jul 2021 05:35GMT-5

Minute: Wed 14 Jul 2021 05:36GMT-5

Minute: Thu 15 Jul 2021 05:37GMT-5

Minute: Fri 16 Jul 2021 05:38GMT-5

Minute: Sat 17 Jul 20