Question

My data structure is a list of tuples in Python, and I’d like to be able to sort the list items by a value contained in their tuples. In PHP, I’d normally create my own sorting function with usort(). Is there an equivalent in Python I could use?

Answer 1

Give the sort() method a key function:

>>> my_list = [(1, 2), (3, 4), (2, 1), (3, 2)]
>>> my_list.sort(key=lambda x: x[1])
>>> my_list
[(2, 1), (1, 2), (3, 2), (3, 4)]
>>> 

If you need to get a sorted list, instead of sorting in place, use the built_in sorted()

>>> sorted(my_list, key=lambda x: x[1])
[(2, 1), (1, 2), (3, 2), (3, 4)]