On Fri, Sep 23, 2011 at 4:14 AM, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > What makes you think it's in C? I don't have Python 3.3a, but in 3.2 the > random module is mostly Python. There is an import of _random, which > presumably is in C, but it doesn't have a randint method:
True. It seems to be defined in cpython/lib/random.py as a reference to randrange, which does a pile of error checking and calls _randbelow... which does a whole lot of work as well as calling random(). Guess I should have checked the code before asking! There's probably good reasons for using randint(), but if you just want a pile of more-or-less random integers, int(random.random()*top) is the best option. > I'm not seeing any significant difference in speed between 2.6 and 3.2: > > [steve@sylar ~]$ python2.6 -m timeit -s "from random import > randint" "randint(0, 1000000)" > 100000 loops, best of 3: 4.29 usec per loop > > [steve@sylar ~]$ python3.2 -m timeit -s "from random import > randint" "randint(0, 1000000)" > 100000 loops, best of 3: 4.98 usec per loop That might be getting lost in the noise. Try the list comp that I had above and see if you can see a difference - or anything else that calls randint that many times. Performance-testing with a heapsort (and by the way, it's _ridiculously_ slower implementing it in Python instead of just calling a.sort(), but we all knew that already!) shows a similar difference in performance. As far as I know, everything's identical between the two (I use // division so there's no floating point getting in the way, for instance), but what takes 90 seconds on Py2 takes 150 seconds on Py3. As with the randint test, I switched int() to long() to test Py2, and that slowed it down a little, but still far far below the Py3 time. I've pasted the code I'm using here: http://pastebin.com/eQPHQhD0 Where's the dramatic performance difference? Or doesn't it matter, since anything involving this sort of operation needs to be done in C anyway? ChrisA -- http://mail.python.org/mailman/listinfo/python-list
