Raymond> Other than possibly upper and lower, the rest should be skipped
Raymond> and left for tests like isdigit(). The tests are faster than
Raymond> the usual linear search style of: if char in str.letters.
A couple people have claimed that the .is*() string methods are faster than
testing a character against a string. I'm sure that's true in some cases,
but it seems not to be true for string.ascii_letters. Here are several
timeit.py runs, ordered from slowest to fastest. Both situations have a
pair of runs, one with a positive test and one with a negative test.
Using char in someset:
% timeit.py -s 'import string, sets; pset = sets.Set(string.ascii_letters)' "'.' in pset"
100000 loops, best of 3: 4.68 usec per loop
% timeit.py -s 'import string, sets; pset = sets.Set(string.ascii_letters)' "'z' in pset"
100000 loops, best of 3: 4.58 usec per loop
Using char.isalpha() or char.islower():
% timeit.py -s 'import string' "'z'.islower()"
1000000 loops, best of 3: 0.93 usec per loop
% timeit.py -s 'import string' "'.'.islower()"
1000000 loops, best of 3: 0.928 usec per loop
% timeit.py -s 'import string' "'z'.isalpha()"
1000000 loops, best of 3: 0.893 usec per loop
% timeit.py -s 'import string' "'.'.isalpha()"
1000000 loops, best of 3: 0.96 usec per loop
Using char in somestring:
% timeit.py -s 'import string; pset = string.ascii_letters' "'z' in pset"
1000000 loops, best of 3: 0.617 usec per loop
% timeit.py -s 'import string; pset = string.ascii_letters' "'.' in pset"
1000000 loops, best of 3: 0.747 usec per loop
Using char in somedict:
% timeit.py -s 'import string; pset = dict(zip(string.ascii_letters,string.ascii_letters))' "'.' in pset"
1000000 loops, best of 3: 0.502 usec per loop
% timeit.py -s 'import string; pset = dict(zip(string.ascii_letters,string.ascii_letters))' "'z' in pset"
1000000 loops, best of 3: 0.509 usec per loop
The only clear loser is the 'char in set' case, no doubt due to its current
Python implementation, however testing a character for membership in a short
string seems to be faster than using the .is*() methods to me.
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