Florian Brucker a écrit :
Hi everybody!
Given a dictionary, I want to create a clustered version of it,
collecting keys that have the same value:
>>> d = {'a':1, 'b':2, 'c':1, 'd':1, 'e':2, 'f':3}
>>> cluster(d)
{1:['a', 'c', 'd'], 2:['b', 'e'], 3:['f']}
That is, generate a new dict which holds for each value of the old dict
a list of the keys of the old dict that have that very value.
>
Another requirement is that it should also work on lists, in that case
with indices instead of keys. We may assume that all values in the
original dict/list can be used as dict keys.
from collections import defaultdict
def cluster(source):
iteritems = getattr(
source, "iteritems",
lambda : enumerate(source)
)
index = defaultdict(list)
for k, v in iteritems():
index[k].append(v)
return index
HTH
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