[Tutor] primes - sieve of odds
Sean Perry
shaleh at speakeasy.net
Sat Mar 26 17:47:49 CET 2005
John Miller wrote:
> How does one actually use this module? For example:
>
> >>> import eratosthenes
> >>> eratosthenes.primes()
> <generator object at 0x640d0>
> >>> eratosthenes.primes().next()
> 2
> >>> eratosthenes.primes().next()
> 2
> >>> eratosthenes.primes().next()
> 2
>
> How does one get beyond the first prime?
>
it = eratosthenes.primes()
it.next()
it.next()
or
# 'it' is shorthand for iterator
def primesToN(n):
it = eratosthenes.primes()
return [ x for x in it if x <= n ]
You were running into problems because the primes() function returns a
new generator. The values are in the generator not the function primes().
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