Re: Shortest prime number program

[Ian Bygrave]

On Sat, 11 Feb 2006 02:03:46 -0800, swisscheese wrote:

> I figured someone out there must have written a minimal code size prime
> number generator. I did not find one after a bit of searching around.
> For primes up to 100 the best I could do was 70 characters (including
> spaces):
> 
> r=range(2,99)
> m=[x*y for x in r for y in r]
> [x for x in r if not x in m]

I swore I'd never play Python golf.

p,r=[],range(2,99)
while r:p,r=p+r[:1],[x for x in r if x%r[0]]

And the result's in p.

--Ian Bygrave

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Re: Shortest prime number program

[Ian Bygrave]

On Sat, 11 Feb 2006 12:43:23 +, Ian Bygrave wrote:
> p,r=[],range(2,99)
> while r:p,r=p+r[:1],[x for x in r if x%r[0]]
> 
> And the result's in p.

Well, given a hypothetical new function 'sieve'

def sieve(f,l):
if not l:
return l
head,tail=l[0],l[1:]
def filter_func(x):
return f(x,head)
tail=filter(filter_func,tail)
return [head]+tail

The prime generation can be reduced to:

from operator import *
sieve(mod,range(2,99))

Is there any precedent for such a function, or any other uses?
 
--Ian Bygrave

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Re: Shortest prime number program

[Ian Bygrave]

On Sat, 11 Feb 2006 13:33:58 +, Ian Bygrave wrote:

> Well, given a hypothetical new function 'sieve'

which should have been:

def sieve(f,l):
if not l:
return l
head,tail=l[0],l[1:]
def filter_func(x):
return f(x,head)
tail=filter(filter_func,tail)
return [head]+sieve(f,tail)

> The prime generation can be reduced to:
> 
> from operator import *
> sieve(mod,range(2,99))

--Ian Bygrave

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