do a sed / awk filter with python tools (at least as fast)

[Peter Otten]

Mathieu Prevot wrote:

> I use in a bourne shell script the following filter:
> 
> sed '/watch?v=/! d;s/.*v=//;s/\(.\{11\}\).*/\1/' \
> | sort | uniq | awk 'ORS=" "{print $1}'
> 
> that give me all sets of 11 characters that follows the "watch?v="
> motif. I would like to do it in python on stdout from a
> subprocess.Popen instance, using python tools rather than sed awk etc.
> How can I do this ? Can I expect something as fast ?

You should either do it in Python , e. g.:

def process(lines):
    candidates = (line.rstrip().partition("/watch?v=") for line in lines)
    matches = (c[:11] for a, b, c in candidates if len(c) >= 11)
    print " ".join(sorted(set(matches)))
              
if __name__ == "__main__":
    import sys
    process(sys.stdin)

or invoke your shell script via subprocess.Popen(). Invoking a python script
via subprocess doesn't make sense IMHO.

Peter