Invert dictionary
Inverts a dictionary with non-unique hashable values.
- Create a
collections.defaultdict
withlist
as the default value for each key. - Use
dictionary.items()
in combination with a loop to map the values of the dictionary to keys usingdict.append()
. - Use
dict()
to convert thecollections.defaultdict
to a regular dictionary.
from collections import defaultdict def collect_dictionary(obj): inv_obj = defaultdict(list) for key, value in obj.items(): inv_obj[value].append(key) return dict(inv_obj) ages = { 'Peter': 10, 'Isabel': 10, 'Anna': 9, } collect_dictionary(ages) # { 10: ['Peter', 'Isabel'], 9: ['Anna'] }