CODEWITHSUNDEEP
pythonlistdictionary
mluebke
mluebke

Reputation: 8829

Ordering a list of dictionaries in python

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 (numerically). 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'},
]

Upvotes: 8

Views: 744

Answers (4)

user106514
user106514

Reputation: 159

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

Upvotes: -1

mluebke
mluebke

Reputation: 8829

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)

Upvotes: 1

dF.
dF.

Reputation: 75845

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

or

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

Upvotes: 23

Greg Case
Greg Case

Reputation: 47471

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)

Upvotes: 1

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