Sort dictionary keys by values ​​in a list?

Question

I have a dictionary and a list. The key values ​​correspond to the values ​​in the list, I'm just trying to figure out how to sort the values ​​in the dictionary according to the values ​​in the list.

>>> l = [1, 2, 37, 32, 4, 3]
>>> d = {
    32: 'Megumi', 
    1: 'Ai',
    2: 'Risa',
    3: 'Eri', 
    4: 'Sayumi', 
    37: 'Mai'
}

I tried using something line by line ...

>>> sorted(dict.keys(), key=list.index)

... but it is obvious that only returns the keys in the correct order.

(It should have realized at 3AM, that listand dictwere horrible names, I changed them to land d, respectively.)

Answer 1

You should not call the dict and list variables, because then you can no longer use the built-in methods. I renamed them in this example.

>>> l = [1, 2, 37, 32, 4]
>>> d = dict = {
...     32: 'Megumi', 
...     1: 'Ai',
...     2: 'Risa',
...     3: 'Eri', 
...     4: 'Sayumi', 
...     37: 'Mai'
... }

dict Python, - - . , Python OrderedDict - google.

, (, ) - , :

>>> s = list((i, d.get(i)) for i in L)
>>> print s
[(1, 'Ai'), (2, 'Risa'), (37, 'Mai'), (32, 'Megumi'), (4, 'Sayumi')]

, :

>>> s = list(d.get(i) for i in L)
>>> print s
['Ai', 'Risa', 'Mai', 'Megumi', 'Sayumi']

, !

Answer 2

dict list

>>> L = [1, 2, 37, 32, 4, 3]
>>> D = {
...     32: 'Megumi',
...     1: 'Ai',
...     2: 'Risa',
...     3: 'Eri',
...     4: 'Sayumi',
...     37: 'Mai'
... }

# Seems roundabout to use sorted here
# This causes an index error for keys in D that are not listed in L
>>> sorted(D.items(), key=lambda x:L.index(x[0]))
[(1, 'Ai'), (2, 'Risa'), (37, 'Mai'), (32, 'Megumi'), (4, 'Sayumi'), (3, 'Eri')]
>>>

# I think this is more direct than using sorted.
# This also ignores/skips keys in D that aren't listed in L
>>> [(i,D[i]) for i in L]
[(1, 'Ai'), (2, 'Risa'), (37, 'Mai'), (32, 'Megumi'), (4, 'Sayumi'), (3, 'Eri')]
>>>

Answer 3

, .

:

• - ,
• : , , .

Answer 4

dict 2- , Python 2.x dictionaty. , :

[(k,dict[k]) for k in sorted(dict.keys(), key=list.index)]

, list. , , :

def _index(x): # Allow non-full key list to be used in sorting
    try: return (list.index(x), x)
    except ValueError: return (sys.maxint, x)

[(k,dict[k]) for k in sorted(dict.keys(), key=_index)]

Answer 5

Python 3.1 OrderedDict:

from collections import OrderedDict

l = [1, 2, 37, 32, 4]
d = {
    32: 'Megumi', 
    1: 'Ai',
    2: 'Risa',
    3: 'Eri', 
    4: 'Sayumi', 
    37: 'Mai'
}

def myindex(element):
    try:
        return l.index(element)
    except ValueError:
        return -1 # nonexisting keys are appended to the beginning of the list

od = OrderedDict(sorted(d.items(), key = lambda t: myindex(t[0])))

print(od)

, , , -1 , (.. ).

OrderedDict([(3, 'Eri'), (1, 'Ai'), (2, 'Risa'), (37, 'Mai'), (32, 'Megumi'), (4, 'Sayumi')])