Python for Software Design: How to Think Like a Computer Scientist by Allen B. Downey

Author:Allen B. Downey [Downey, Allen B.]
Language: eng
Format: mobi, pdf
Publisher: Cambridge University Press
Published: 2009-03-09T00:00:00+00:00

11.1 DICTIONARY AS A SET OF COUNTERS

Suppose you are given a string and you want to count how many times each letter appears. There are several ways you could do it:(i) You could create 26 variables, one for each letter of the alphabet. Then you could traverse the string and, for each character, increment the corresponding counter, probably using a chained conditional.

(ii) You could create a list with 26 elements. Then you could convert each character to a number (using the built-in function ord), use the number as an index into the list, and increment the appropriate counter.

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