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Code: Alles auswählen

In [1]: d = {'a': 1, 'b': 2}                                                                                                                                  

In [2]: d                                                                                                                                                     
Out[2]: {'a': 1, 'b': 2}

In [3]: e = {value: key for key, value in d.items()}                                                                                                          

In [4]: e                                                                                                                                                     
Out[4]: {1: 'a', 2: 'b'}

Code: Alles auswählen

>>> d = {'a': 1, 'b': 2, 'c': 1}
>>> e = {value: key for key, value in d.items()}
>>> e
{1: 'c', 2: 'b'}  # wo ist a?

Code: Alles auswählen

>>> from collections import defaultdict
>>> e = defaultdict(list)
>>> for k, v in d.items():
...     e[v].append(k)
... 
>>> e
defaultdict(<class 'list'>, {1: ['a', 'c'], 2: ['b']})
>>> dict(e)
{1: ['a', 'c'], 2: ['b']}