"is not" vs. != in python

[ArgentPyro]

I'm currently working on optimizing some python code, and was wondering which runs faster, "is not" or != or does it not matter:

Code: Select all

n = 10

if n is not 5:
print "Done"

if n != 5:
print "Done"

Thanks.

[tgoe]

I think the 'is' operator is probably faster as all it does is check whether the objects compared have the same address in memory. It doesn't look at values at all so you have to be careful:

Code: Select all

>>> a = [1,2,3]
>>> b = [1,2,3]
>>> a is b
False
>>> a == b
True


[ArgentPyro]

thanks