Question

How can I sort a list by a key described by an arbitrary function? For example, if I have:

mylist = [["quux", 1, "a"], ["bar", 0, "b"]]

I’d like to sort “mylist” by the second element of each member, e.g.

sort(mylist, key=lambda x: x[1])

how can I do this?

Answer 1

You basically have it already:

>>> mylist = [["quux", 1, "a"], ["bar", 0, "b"]]
>>> mylist.sort(key=lambda x: x[1])
>>> print mylist

gives:

[['bar', 0, 'b'], ['quux', 1, 'a']]

That will sort mylist in place.

[this para edited thanks to @Daniel’s correction.] sorted will return a new list that is sorted rather than actually changing the input, as described in http://wiki.python.org/moin/HowTo/Sorting/.