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comp.lang.python

Re: Chaining 501 generators breaks everything?

Jonathan Gardner

2/19/2010 9:48:00 PM

On Fri, Feb 19, 2010 at 11:47 AM, Andrey Fedorov <anfedorov@gmail.com> wrote:
> I implemented a Sieve of Eratosthenes primes algorithm using generators:
>
> http://gist.github....
>
> This code which chains together 500 generators works fine (~1/20th of a
> second) on my laptop.
>

You may want a more traditional approach. Until Python gets tail
recursion (doubtful), this won't work very well on any platform.

#!/usr/bin/env python

from itertools import islice, count
from time import time

def primes():
seen = []
for i in count(2):
for s in seen:
if i%s == 0:
break
else: # Run if the for loop doesn't break
seen.append(i)
yield i

start = time()
for i in islice(primes(), 0, 10000):
print i
print time() - start

--
Jonathan Gardner
jgardner@jonathangardner.net