sort string by number inside

Question

I would like to know how can I sort a string by the number inside.

As example I have:

hello = " hola %d" % (number_from_database)
bye = "adios %d" % (number_from_database_again)

I want to sort them by the number even if it changes.

Do you have a list of these to sort? Sort them compared to what? — Martijn Pieters, Jun 05 '13 at 17:42
for example sometimes the user can sorts in the web "bye" before than hello so hello = "hola 2" and bye = "adios 1" or sometimes the user can sorts hello before bye so i want to know how to sort them bye the number inside, thank you :D — Victor Castillo Torres, Jun 05 '13 at 17:45
That doesn't make this any clearer. Sorting applies to a sequence of items; all you have is two variables, `hello` and `bye`. — Martijn Pieters, Jun 05 '13 at 17:46
This is called "natural" sorting, see http://stackoverflow.com/q/11150239/989121 and the links therein for examples. — georg, Jun 05 '13 at 17:49

score 13 · Accepted Answer · edited May 23 '17 at 12:08

13

You can pass a key to sort:

sorted(l, key=lambda x: int(re.sub('\D', '', x)))

For example:

In [1]: import re

In [2]: l = ['asdas2', 'asdas1', 'asds3ssd']

In [3]: sorted(l, key=lambda x: int(re.sub('\D', '', x)))
Out[3]: ['asdas1', 'asdas2', 'asds3ssd']

Where re.sub('\D', '', x) replaces everything but the digits.

edited May 23 '17 at 12:08

Community

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answered Jun 05 '13 at 17:48

Andy Hayden

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Man, you are like a god that works, thanks for your answer I do not know how can i thank you. God Bless you – Victor Castillo Torres Jun 05 '13 at 17:53
But I have 14 reputation tu opvote I require 15, I'll upvote when i have 15 – Victor Castillo Torres Jun 05 '13 at 18:13

score 1 · Answer 2 · answered Dec 06 '17 at 11:58

1

Just a little complement to Andy's answer.

If you want to sort set which also contain strings without any number:

sorted(l, key=lambda x: int('0'+re.sub('\D', '', x)))

, which would put those strings without any number at the very beginning.

answered Dec 06 '17 at 11:58

Yuan Tao

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score 0 · Answer 3 · answered Mar 27 '23 at 20:14

The solutions above do not work for strings with the format:

test 8 - test 18

The following code will return 818 instead of 8:

x = 'test 8 - test 18'
res = int(re.sub(r'\D', '', x))
print(res)

>>> 818

The solution for this is doing a search and getting the group result:

x = 'test 8 - test 18'
res = int(re.search(r'\d+', x).group())
print(res)

>>> 8

So, the final solution with this correction is:

l = [
   'test 9 - test 8',
   'test 8 - test 18'
]

l2 = sorted(l, key=lambda x: int(re.search(r'\d+', x).group()))

print(l)
print(l2)

>>> ['test 9 - test 8', 'test 8 - test 18']
['test 8 - test 18', 'test 9 - test 8']

score -1 · Answer 4 · answered Jun 05 '13 at 17:48

-1

salutations = [hello, bye]
salutations.sort(key=lambda x: int(filter(lambda s: s.isdigit(), x.split())[0]))

answered Jun 05 '13 at 17:48

mVChr

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sort string by number inside

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