# numsort.py
# sorting in numeric order
# for example:
# ['aaa35', 'aaa6', 'aaa261']
# is sorted into:
# ['aaa6', 'aaa35', 'aaa261']
import sys
def sorted_copy(alist):
# inspired by Alex Martelli
# http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52234
indices = map(_generate_index, alist)
decorated = zip(indices, alist)
decorated.sort()
return [ item for index, item in decorated ]
def _generate_index(str):
"""
Splits a string into alpha and numeric elements, which
is used as an index for sorting"
"""
#
# the index is built progressively
# using the _append function
#
index = []
def _append(fragment, alist=index):
if fragment.isdigit(): fragment = int(fragment)
alist.append(fragment)
# initialize loop
prev_isdigit = str[0].isdigit()
current_fragment = ''
# group a string into digit and non-digit parts
for char in str:
curr_isdigit = char.isdigit()
if curr_isdigit == prev_isdigit:
current_fragment += char
else:
_append(current_fragment)
current_fragment = char
prev_isdigit = curr_isdigit
_append(current_fragment)
return tuple(index)
def _test():
initial_list = [ '35 Fifth Avenue', '5 Fifth Avenue', '261 Fifth Avenue' ]
sorted_list = sorted_copy(initial_list)
import pprint
print "Before sorting..."
pprint.pprint (initial_list)
print "After sorting..."
pprint.pprint (sorted_list)
print "Normal python sorting produces..."
initial_list.sort()
pprint.pprint (initial_list)
if __name__ == '__main__':
_test()
