sorting by first group element in python

Question

Hi,

I was wondering how can I make python order my collection of tuples so that first similar items would appear grouped and groups ordered by first item.

order group
3     1
4     2
2     2
1     1

After sort

order group
1     1
3     1
2     2
4     2

Python list

unordered = [(3, 1), (4, 2), (2, 2), (1, 1)]

Answer 1

I assume you meant unordered = [(3, 1), (4, 2), (2, 2), (1, 1)] because that part of your example as you typed it is incompatible with the other two, right?

If so, then

>>> import operator
>>> sorted(unordered, key=operator.itemgetter(1,0))
[(1, 1), (3, 1), (2, 2), (4, 2)]

or similarly unordered.sort(key=operator.itemgetter(1,0)) if you wanted to sort in place (which given the variable name I'm pretty sure you don't -- it would be seriously weird to name a variable "unordered" if it's meant to be ordered!-).