Shashwat Anand wrote:
I intended to sort a list which sorts according to user-defined custom
sorting-order.
For example: If sorting-order is "zabc...wxy", then the output will be
in lexicographically sorted order but z will always be given priority
over rest others.
as a test case i took sorting order as reverse of normal sorting, hence
i defined user_key as string.ascii_lowercase. It should sort in reverse
manner but I'm not getting expected output.
(Even though it could have just been sorted as reverse=True, but my
intention is to generalize it for this is just a test-case). I'm not
able to find where the bug lies nor am i exactly sure how the key
function works, even though i use it in a regular fashion. Can you guys
help me out ?
Your code is not wrong. It's your expected output (or your need) that's
different from a typical definition of "lexicographical sorting". In a
typical lexicographical sorting "a" comes before "ab" since "a" is
shorter than "ab".
So, if you want this:
expected output: ['cba', 'cab', 'abc', 'ab', 'aa', 'a']
you must use a custom cmp= argument to reverse the shorter substring case:
like this:
import string
def my_cmp(s1, s2):
if s1.startswith(s2):
return -1
elif s2.startswith(s1):
return 1
else:
return cmp(s1, s2)
def userdef_sort(l, user_key):
table = string.maketrans("".join(sorted(user_key)), user_key)
trans = lambda x: x.translate(table)
return sorted(l, cmp=my_cmp, key=trans)
#user_key = raw_input()
user_key = string.ascii_lowercase[::-1]
l = ['a', 'aa', 'ab', 'abc', 'cba', 'cab']
print userdef_sort(l, user_key)
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