Michael Johnston Michael Johnston -4 years ago 128
Python Question

dict.fromkeys all point to same list

This was causing me a bit of grief...

I created a dictionary from a list

l = ['a','b','c']
d = dict.fromkeys(l, [0,0]) # initializing dictionary with [0,0] as values

d['a'] is d['b'] # returns True

How can I make each value of the dictionary a seperate list? Is this possible without iterating over all keys and setting them equal to a list? I'd like to modify one list without changing all the others.

Answer Source

You could use a dict comprehension:

>>> keys = ['a','b','c']
>>> value = [0, 0]
>>> {key: list(value) for key in keys}
    {'a': [0, 0], 'b': [0, 0], 'c': [0, 0]}
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