searching for the number of occurences of a string

hi;
say i have a text file with a string ( say '(XYZ)') and I want to find
the number of line where this string has occured. What is the best way
to do that?

what about if that string was say a 0 with leading and trailing white
spaces, would that be any different?

thanks
moe smadi

re: searching for the number of occurences of a string

M.N.A.Smadi wrote:[color=blue]
> hi;
> say i have a text file with a string ( say '(XYZ)') and I want to find
> the number of line where this string has occured. What is the best way
> to do that?
>
> what about if that string was say a 0 with leading and trailing white
> spaces, would that be any different?
>
> thanks
> moe smadi[/color]

Some pieces:

To read every line in a file:

afile = open(filename)
for aline in afile:
do_something_here()

To see if a string contains another string, try

if another_string() in astring:
do_something_else_here()

If you need regular expressions, see the re module.

For instance:

import re
regex = re.compile(r'(?:\s+0\s+)|\(XYZ\)')

print regex.search(' 0 ').group()
print regex.search(' (XYZ) abc').group()

if regex.search('abcdefg'):
print 'yep'
else:
print 'nope'

That should be everything you could possibly need. Its up to you to put
it all together.

James
--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/

re: searching for the number of occurences of a string

M.N.A.Smadi wrote:[color=blue]
> hi;
> say i have a text file with a string ( say '(XYZ)') and I want to find
> the number of line where this string has occured. What is the best way
> to do that?
>
> what about if that string was say a 0 with leading and trailing white
> spaces, would that be any different?
>
> thanks
> moe smadi[/color]


To read every line in a file:

afile = open(filename)
for aline in afile:
do_something_here()
afile.close()

To see if a string contains another string, try

if another_string in astring:
do_something_else_here()

If you need regular expressions, see the re module.

For instance:

import re
regex = re.compile(r'(?:\s+0\s+)|\(XYZ\)')

print regex.search(' 0 ').group()
print regex.search(' (XYZ) abc').group()

if regex.search('abcdefg'):
print 'yep'
else:
print 'nope'

That should be everything you could possibly need. Its up to you to put
it all together.
--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/

re: searching for the number of occurences of a string

> hi;[color=blue]
> say i have a text file with a string ( say '(XYZ)') and I want to find
> the number of line where this string has occured. What is the best way
> to do that?[/color]

I would suggest:

# Read file contents
lines = file('filename.txt').readlines()
# Extract first line number containing 'XYZ' string
[(i, l) for (i, l) in enumerate(lines) if 'XYZ' in l][0][0]

Best regards,
Marek