Sent today to python-list ...
Inspired by recent threads (and recalling my first message to Python
edu-sig), I did some Internet searching on producing prime numbers using
Python generators. Most algorithms I found don't go for the infinite,
contenting themselves with "list all the primes below a given number".
Here's a very Pythonic (IMHO) implementation that keeps going and going and
going ...:
from itertools import count
from math import sqrt
def prime_gen():
"""
Generate all prime numbers
"""
primes = []
for n in count(2):
if all(n%p for p in primes if p <= sqrt(n)):
primes.append(n)
yield n
The use of all() is particularly nifty (see
http://code.activestate.com/recipes/576640/). And so is the way in which the
list comprehension easily incorporates the sqrt(n) optimization.
Question: Is there a way to implement this algorithm using generator
expressions only -- no "yield" statements allowed?
E-mail message checked by Spyware Doctor (6.0.0.386)
Database version: 5.12110
http://www.pctools.com/en/spyware-doctor-antivirus/
_______________________________________________
Edu-sig mailing list
Edu-sig@python.org
http://mail.python.org/mailman/listinfo/edu-sig
