On Mon, 06 Feb 2012 02:27:38 +0100, Matej Cepl wrote: > Strange thing is that this unit tests correctly with python3, but fails > with python2. The problem is that apparently python3 random.choice picks > different element of self[k] than the one python2 (at least, both of > them are constant in their choice).
Confirmed: steve@runes:~$ python2.6 -c "from random import choice, seed; seed(1); print choice(range(1000))" 134 steve@runes:~$ python3.2 -c "from random import choice, seed; seed(1); print(choice(list(range(1000))))" 137 steve@runes:~$ python2.6 -c "from random import choice, seed; seed(42); print choice(range(1000))" 639 steve@runes:~$ python3.2 -c "from random import choice, seed; seed(42); print(choice(list(range(1000))))" 654 > Is it known that there is this difference? Is there a way how to make > both random.choice select the same? Reading the docs, I would expect that when using an int as seed, you should get identical results. There is no mention that the PRNG has changed between 2.6 and 3.2; both should use the given int as seed. There is a change of behaviour when using strings/bytes/bytearrays, and Python3.2 provides a "version=N" argument to seed to set the old behaviour. But this doesn't apply to integer seeds. I call this a bug. It appears to be a bug in 3.2, because 3.1 gives the same results as 2.6: steve@runes:~$ python3.1 -c "from random import choice, seed; seed(42); print(choice(list(range(1000))))" 639 steve@runes:~$ python3.1 -c "from random import choice, seed; seed(1); print(choice(list(range(1000))))" 134 -- Steven -- http://mail.python.org/mailman/listinfo/python-list
