Python analog of PHP's natsort function (sort

问题:

I would like to know if there is something similar to PHP natsort function in Python?

l = [\'image1.jpg\', \'image15.jpg\', \'image12.jpg\', \'image3.jpg\']
l.sort()

gives:

[\'image1.jpg\', \'image12.jpg\', \'image15.jpg\', \'image3.jpg\']

but I would like to get:

[\'image1.jpg\', \'image3.jpg\', \'image12.jpg\', \'image15.jpg\']

UPDATE

Solution base on this link

def try_int(s):
    \"Convert to integer if possible.\"
    try: return int(s)
    except: return s

def natsort_key(s):
    \"Used internally to get a tuple by which s is sorted.\"
    import re
    return map(try_int, re.findall(r\'(\\d+|\\D+)\', s))

def natcmp(a, b):
    \"Natural string comparison, case sensitive.\"
    return cmp(natsort_key(a), natsort_key(b))

def natcasecmp(a, b):
    \"Natural string comparison, ignores case.\"
    return natcmp(a.lower(), b.lower())

l.sort(natcasecmp);

回答1:

From my answer to Natural Sorting algorithm:

import re
def natural_key(string_):
    \"\"\"See http://www.codinghorror.com/blog/archives/001018.html\"\"\"
    return [int(s) if s.isdigit() else s for s in re.split(r\'(\\d+)\', string_)]

Example:

>>> L = [\'image1.jpg\', \'image15.jpg\', \'image12.jpg\', \'image3.jpg\']
>>> sorted(L)
[\'image1.jpg\', \'image12.jpg\', \'image15.jpg\', \'image3.jpg\']
>>> sorted(L, key=natural_key)
[\'image1.jpg\', \'image3.jpg\', \'image12.jpg\', \'image15.jpg\']

To support Unicode strings, .isdecimal() should be used instead of .isdigit(). See example in @phihag\'s comment. Related: How to reveal Unicodes numeric value property.

.isdigit() may also fail (return value that is not accepted by int()) for a bytestring on Python 2 in some locales e.g., \'\\xb2\' (\'²\') in cp1252 locale on Windows.

回答2:

You can check out the third-party natsort library on PyPI:

>>> import natsort
>>> l = [\'image1.jpg\', \'image15.jpg\', \'image12.jpg\', \'image3.jpg\']
>>> natsort.natsorted(l)
[\'image1.jpg\', \'image3.jpg\', \'image12.jpg\', \'image15.jpg\']

Full disclosure, I am the author.

回答3:

This function can be used as the key= argument for sorted in Python 2.x and 3.x:

def sortkey_natural(s):
    return tuple(int(part) if re.match(r\'[0-9]+$\', part) else part
                for part in re.split(r\'([0-9]+)\', s))