python vs. grep

[Arnaud Delobelle]

Anton Slesarev <slesarev.anton at gmail.com> writes:

> f = open("bigfile",'r')
>
> flines = (line for line in f if pat.search(line))
> c=0
> for x in flines:
>     c+=1
> print c

It would be simpler (and probably faster) not to use a generator expression:

search = re.compile('sometext').search

c = 0
for line in open('bigfile'):
    if search(line):
         c += 1

Perhaps faster (because the number of name lookups is reduced), using
itertools.ifilter:

from itertools import ifilter

c = 0
for line in ifilter(search, 'bigfile'):
    c += 1


If 'sometext' is just text (no regexp wildcards) then even simpler:

...
for line in ...:
    if 'sometext' in line:
         c += 1

I don't believe you'll easily beat grep + wc using Python though.

Perhaps faster?

sum(bool(search(line)) for line in open('bigfile'))
sum(1 for line in ifilter(search, open('bigfile')))

...etc...

All this is untested!
-- 
Arnaud