Ordering a list of dictionaries in python

Question

I've got a python list of dictionaries:

mylist = [
{'id':0, 'weight':10, 'factor':1, 'meta':'ABC'},
{'id':1, 'weight':5, 'factor':1, 'meta':'ABC'},
{'id':2, 'weight':5, 'factor':2, 'meta':'ABC'},
{'id':3, 'weight':1, 'factor':1, 'meta':'ABC'}
]

Whats the most efficient/cleanest way to order that list by weight then factor (numericaly). The resulting list should look like:

mylist = [
{'id':3, 'weight':1, 'factor':1, 'meta':'ABC'},
{'id':1, 'weight':5, 'factor':1, 'meta':'ABC'},
{'id':2, 'weight':5, 'factor':2, 'meta':'ABC'},
{'id':0, 'weight':10, 'factor':1, 'meta':'ABC'},
]

Answer 1

Something along the lines of the following ought to work:

def cmp_dict(x, y):
    weight_diff = y['weight'] - x['weight']
    if weight_diff == 0:
        return y['factor'] - x['factor']
    else:
        return weight_diff

myList.sort(cmp_dict)

Answer 2

mylist.sort(key=lambda d: (d['weight'], d['factor']))

or

import operator
mylist.sort(key=operator.itemgetter('weight', 'factor'))

Answer 3

I accepted dF's answer for the inspiration, but here is what I ultimately settled on for my scenario:

@staticmethod
def ordered_list(mylist):
    def sort_func(d):
        return (d['weight'], d['factor'])

    mylist.sort(key=sort_func)

Answer 4

decoratedlist = [(item[weight], item) for item in mylist]
decoratedlist.sort()
results = [item for (key, item) in decoratedlist]