python assignment of complex objects -

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i have following code works fine. minute remove comment across statement print list(b) fails , returns empty list. i'm thinking perhaps x getting address location of list(b) executed part of print statement. 

import itertools = [1,2,3] b = itertools.product(a,repeat=2) print str(b) #print list(b) x = list(b) print x <itertools.product object @ 0x7f5ac40a9a50> [(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), (3, 3)] command took 0.03s

b iterator. if ask list(b) exhaust iterator, causing empty next time list(b).

as rule-of-thumb: when dealing iterators, need assign them names. usually, either iterate on iterator for-in, or use list convert iterator list.


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