从dict创建OrderedDict，列表类型的值（按列表值的顺序）

Question

It is a bit hard for me to explain it in words, so I'll show an example:

What I have (data is a dict instance):

data = {'a':[4,5,3], 'b':[1,0,2], 'c':[6,7,8]}

What I need ( ordered_data is an OrderedDict instance):

ordered_data = {'b':[0,1,2], 'a':[3,4,5], 'b':[6,7,8]}

The order of keys should be changed with respect to order of items in nested lists

Answer 1

tmp = {k:sorted(v) for k,v in data.items()}
ordered_data = OrderedDict((k,v) for k,v in sorted(tmp.items(), key=lambda i: i[1]))

First sort the values. If you don't need the original data , it's OK to do this in place, but I made a temporary variable.

key is a function that returns a key to be sorted on. In this case, the key is the second element of the item tuple (the list), and since lists are comparable, that's good enough.

Answer 2

You can use OrderedDict by sorting your items and the values :

>>> from operator import itemgetter
>>> from collections import OrderedDict
>>> d = OrderedDict(sorted([(k, sorted(v)) for k, v in data.items()], key=itemgetter(1)))
>>> d
OrderedDict([('b', [0, 1, 2]), ('a', [3, 4, 5]), ('c', [6, 7, 8])])

Answer 3

Usually, you should not worry about the data order in the dictionary itself, and instead, jsut order it when you retrieve the dictionary's contents (ie: iterate over it):

data = {'a':[4,5,3], 'b':[1,0,2], 'c':[6,7,8]}
for datum in sorted(data.items(), key=lambda item: item[1]):
    ...