Unwanted behaviour from dict.fromkeys

Question

I\'d like to initialise a dictionary of sets (in Python 2.6) using dict.fromkeys, but the resulting structure behaves strangely. More specifically:

Answer 1

The reason its working this way is that set([]) creates an object (a set object). Fromkeys then uses that specific object to create all its dictionary entries. Consider:

>>> x
{0: set([]), 1: set([]), 2: set([]), 3: set([]), 4: set([]), 5: set([]), 
6: set([]), 7: set([]), 8: set([]), 9: set([])}
>>> x[0] is x[1]
True

All the sets are the same!