re.search much slower then grep on some regular expressions

Bruno Desthuilliers bruno.42.desthuilliers at websiteburo.invalid
Fri Jul 4 14:29:56 CEST 2008


Henning_Thornblad a écrit :
> What can be the cause of the large difference between re.search and
> grep?
> 
> This script takes about 5 min to run on my computer:
> #!/usr/bin/env python
> import re
> 
> row=""
> for a in range(156000):
>     row+="a"
> print re.search('[^ "=]*/',row)
> 
> 
> While doing a simple grep:
> grep '[^ "=]*/' input                  (input contains 156.000 a in
> one row)
> doesn't even take a second.
> 
> Is this a bug in python?

Please re-read carefully your python code. Don't you think there's a 
subtle difference between reading a file and buildin 156000 string objects ?




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