[racket] a small programming exercise

From: Shriram Krishnamurthi (sk at cs.brown.edu)
Date: Thu Oct 14 00:10:34 EDT 2010

Given: A list of numbers.  Assume integers (though it isn't necessary
for the underlying issue).

Task: To determine how often the first digit is 1, the first digit is
2, ..., the first digit is 9, and present as a table.  You may exploit
DrRacket's pretty-printer, e.g., by using a list of lists:

'((#\1 22.51539138082674)
  (#\2 16.44678979771328)
  (#\3 15.567282321899736)
  (#\4 12.401055408970976)
  (#\5 9.058927000879507)
  (#\6 7.651715039577836)
  (#\7 6.420404573438875)
  (#\8 5.804749340369393)
  (#\9 4.133685136323659))

I leave the precise format of the output unstated so you're free to
choose a clever representation; your answer should be at least as
visually clear as the above.

You should not mutate the original list, since it may be necessary for
other computations.



PS: Of course, this is to explore Benford's Law:


    which is the subject of my lecture tomorrow.  The above
    distribution is from the size of the littoral zone (in acres) of
    the lakes of Minnesota.

PPS: If you really want to you can assume the data are actually in a
     CSV file (as mine are -- thanks, Neil!), in case you can come up
     with something even cleverer.

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