Sort list of lists of strings in Python

Question

How can I sort the following based on the 1st element?

list1 = [["Value313",1],["Value421",3],["Value234",2]]

Ultimately, I should get the following:

list1 = [["Value234",2],["Value313",1],["Value421",3]]

Answer 1

The default sort order of lists (lexicographically) is already how you want it.

>>> list1 = [["Value313",1],["Value421",3],["Value234",2]]
>>> list1.sort()
>>> print list1
[['Value234', 2], ['Value313', 1], ['Value421', 3]]

Answer 2

sorted(list1,key=lambda x : x[0])

[['Value234', 2], ['Value313', 1], ['Value421', 3]]

Use sorted and use a key lambda x[0] where x[0] is the first element in each sublist

Or sort in place to avoid creating a new list:

list1 = [["Value313",1],["Value421",3],["Value234",2]]

list.sort(list1,key=lambda x : x[0])
print list1
[['Value234', 2], ['Value313', 1], ['Value421', 3]]

Answer 3

To sort list1 in place (without creating another list) use:

from operator import itemgetter
list1.sort(key=itemgetter(0))

If you want to create another list and leave list1 unsorted use:

from operator import itemgetter
list2 = sorted(list1, key=itemgetter(0))

You could use a lambda, but operator.itemgetter normally has better performance since it's at C level.