In a past lesson we counted the occurrences of each digit in $\pi$. This lesson is a bit of a repeat of that lesson, but does an analysis using arrays and the creation of a professional looking histogram chart.

In this case, each digit of $\pi$ is read from the variable bigpi. Each digit is used as an index into an array called hist that keeps track of the number of times a given digit occurs in bigpi. Another array called digit is used to seed the horizontal axis of the histogram, as it is loaded with the numbers from 0 to 9, which are the possible digits in $\pi$.

hist={}

digit={}

​

for i=0,9 do

 digit[i] = ???

 hist[i] = ???

end

​

for i=1,string.len(bigpi) do

 d = string.sub(bigpi,i,i)

 if (d ~= ".") then

   d=tonumber(d)

   hist[d] = ???

 end

end

​

drawchart(digit,hist,"bar")