crosswired crosswired - 2 months ago 7
Python Question

python sort strings with digits at the end

what is the easiest way to sort a list of strings with digits at the end where some have 3 digits and some have 4:

>>> list = ['asdf123', 'asdf1234', 'asdf111', 'asdf124']
>>> list.sort()
>>> print list
['asdf111', 'asdf123', 'asdf1234', 'asdf124']


should put the 1234 one on the end. is there an easy way to do this?

Answer

is there an easy way to do this?

No

It's perfectly unclear what the real rules are. The "some have 3 digits and some have 4" isn't really a very precise or complete specification. All your examples show 4 letters in front of the digits. Is this always true?

import re
key_pat = re.compile(r"^(\D+)(\d+)$")
def key(item):
    m = key_pat.match(item)
    return m.group(1), int(m.group(2))

That key function might do what you want. Or it might be too complex. Or maybe the pattern is really r"^(.*)(\d{3,4})$" or maybe the rules are even more obscure.

>>> data= ['asdf123', 'asdf1234', 'asdf111', 'asdf124']
>>> data.sort( key=key )
>>> data
['asdf111', 'asdf123', 'asdf124', 'asdf1234']