Comments on: PHP Faster than Python?

By: Jaime Pinheiro

Jaime Pinheiro — Mon, 28 Mar 2011 21:00:41 +0000

Don’t you forget that array in PHP isn’t really an array, but an array of key => value pair, just like a hash or dictionary. For that reason, working with arrays in PHP isn’t not as fast it could be and it’s obviously slower than a REAL array should.

Try to compare it to a similar Python object, rather than a simple [].

By: A.K.

A.K. — Wed, 11 Feb 2009 00:59:01 +0000

Brandon,
LOL, you are such a prick.

Antti,
Those are very interesting observations. I would expect the same results for the same modifications in PHP as well. Sorry about the formatting, I didn’t install a plugin for comment coding.

By: Antti Kaihola

Antti Kaihola — Tue, 10 Feb 2009 09:57:14 +0000

I tried the following subtle changes to see how they affect the performance:

import array ; primeNumbers = array(‘L’)
-> almost twice as slow

if 0 == i % number:
-> no change

if not i % number:
-> slight speedup

divisible = [1 for number in primeNumbers if i % number == 0]
if not divisible:
-> no change

divisible = [1 for number in primeNumbers if not i % number]
if not divisible:
-> slight speedup

That’s all I could come up with without significantly changing what the code does.

Two interesting variations which superficially don’t change the algorithm but actually stop the loop at first match:

divisible = (1 for number in primeNumbers if i % number == 0)
try:
divisible.next()
except StopIteration:
primeNumbers.append(i)

A version using Python 2.5 any():

for i in xrange(2, 10000):
divisible = any(i % number == 0 for number in primeNumbers)
if not divisible:
primeNumbers.append(i)

These two of course are in fact changing the algorithm.

(by the way, you have no help for comment formatting so I don’t know if my code blocks will format correctly)

By: bwilliam

bwilliam — Tue, 10 Feb 2009 08:35:52 +0000

Haha. This is great. AK FTW.