python - How to swap keys with values in a dictionary -

the output should contain keys , values original dictionary:

dicts = {1: 'a', 2: 'b', 3: 'a', 4: 'a'}

however, when try swap result is:

{'a': 4, 'b': 2}

how can solve problem?

not sure answering question fully, because bit confusing. in comments above, show want reverse key/value of 1 : a 'a' : 1.

you might find collections module useful.

import collections  d = collections.defaultdict(list)  dicts = {1:'a', 2:'b', 3:'a', 4:'a'}  key, value in dicts.items():     d[value].append(key)

then try output:

>>> d defaultdict(<type 'list'>, {'a': [1, 3, 4], 'b': [2]})

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