Question

What is the easiest way to create a dictionary from an iterable and assigning it some default value? I tried:

>>> x = dict(zip(range(0, 10), range(0)))

But that doesn’t work since range(0) is not an iterable as I thought it would not be (but I tried anyways!)

So how do I go about it? If I do:

>>> x = dict(zip(range(0, 10), 0))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: zip argument #2 must support iteration

This doesn’t work either. Any suggestions?

Answer 1

You need the dict.fromkeys method, which does exactly what you want.

From the docs:

fromkeys(...)
    dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v.
    v defaults to None.

So what you need is:

>>> x = dict.fromkeys(range(0, 10), 0)
>>> x
{0: 0, 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0, 8: 0, 9: 0}