Stripping everything but alphanumeric chars from a string in Python

Question

What is the best way to strip all non alphanumeric characters from a string, using Python?

The solutions presented in the PHP variant of this question will probably work with some minor adjustments, but don't seem very 'pythonic' to me.

For the record, I don't just want to strip periods and commas (and other punctuation), but also quotes, brackets, etc.

Answer 1

I just timed some functions out of curiosity. In these tests I'm removing non-alphanumeric characters from the string string.printable (part of the built-in string module). The use of compiled '[W_]+' and pattern.sub('', str) was found to be fastest.

$ python -m timeit -s 
     "import string" 
     "''.join(ch for ch in string.printable if ch.isalnum())" 
10000 loops, best of 3: 57.6 usec per loop

$ python -m timeit -s 
    "import string" 
    "filter(str.isalnum, string.printable)"                 
10000 loops, best of 3: 37.9 usec per loop

$ python -m timeit -s 
    "import re, string" 
    "re.sub('[W_]', '', string.printable)"
10000 loops, best of 3: 27.5 usec per loop

$ python -m timeit -s 
    "import re, string" 
    "re.sub('[W_]+', '', string.printable)"                
100000 loops, best of 3: 15 usec per loop

$ python -m timeit -s 
    "import re, string; pattern = re.compile('[W_]+')" 
    "pattern.sub('', string.printable)" 
100000 loops, best of 3: 11.2 usec per loop