-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 07/14/2011 11:47 AM, Tres Seaver wrote:
> While we're at it, 'list.insert(0,foo)' is known to be slower in a > tight loop than 'list.append(foo)', with a 'reversed' at the end of > the loop:: > > $ python -m timeit -s "from string import letters" "path = []" \ "for > letter in letters: path.append(letter)" \ "result = > tuple(reversed(path))" 100000 loops, best of 3: 15.9 usec per loop > > $ python -m timeit -s "from string import letters" "path = []" \ "for > letter in letters: path.insert(0, letter)" \ "result = tuple(path)" > 10000 loops, best of 3: 25.3 usec per loop > > > For the sake of comparison, the original tuple addition is actually > between the two: > > $ python -m timeit -s "from string import letters" "result = ()" \ > "for letter in letters: result += (letter,)" 10000 loops, best of 3: > 21.6 usec per loop A further micro-optimization is to pre-allocate a big list in a thread local. Running the attached script produces:: $ python perftest.py Via insert_0: 24.8401839733 Via append: 15.6596238613 speedup: 37.0% Via tuple_add: 21.9555268288 speedup: 11.6% Via prealloc: 10.5278339386 speedup: 57.6% Tres. - -- =================================================================== Tres Seaver +1 540-429-0999 tsea...@palladion.com Palladion Software "Excellence by Design" http://palladion.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk4fIVAACgkQ+gerLs4ltQ6BlACguSHcHLWGjVIVJlQYIpL42RNc mqMAn1Y16tyVmUkxd2ipNrZSeZpSFVEA =oJJY -----END PGP SIGNATURE-----
perftest.py
Description: application/httpd-cgi
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