python - Sorting list of lists by the first element of each sub-list

Question

How to sort a list of lists according to the first element of each list?

For example, giving this unsorted list:

[[1,4,7],[3,6,9],[2,59,8]]

The sorted result should be:

[[1,4,7],[2,59,8],[3,6,9]]

Answer 1

Use sorted function along with passing anonymous function as value to the key argument. key=lambda x: x[0] will do sorting according to the first element in each sublist.

>>> lis = [[1,4,7],[3,6,9],[2,59,8]]
>>> sorted(lis, key=lambda x: x[0])
[[1, 4, 7], [2, 59, 8], [3, 6, 9]]