[Python] number of lines in a file

Joseph Youssef

len(open('/path/and/filename').readlines())

Alternatively:

os.system("wc -l %s" % filename)

In article <slrnaa9b09.i04.philh at comuno.freeserve.co.uk>,
philh at comuno.freeserve.co.uk says...
Except that this is platform-specific for *nix, whereas
len(file.readlines()) works on all Python platforms.

f = open(filename)
lines = f.readlines()
f.close()

print "%s has %d lines." % (filename, len(lines))

// mark

-----Original Message-----
From: python-list-admin at python.org [mailto:python-list-admin at python.org]On
Behalf Of Joseph Youssef
Sent: Thursday, March 28, 2002 9:26 PM
To: python-list at python.org
Subject: number of lines in a file


hello, I am nwe to Python and I'm trying to write this script but I need it
to check how many lines is in the file and I don't know how so I'm hoping
someone could tell me.

"Joseph Youssef" <leader730 at hotmail.com> wrote in message news:<b0%o8.22778$Li5.504465 at weber.videotron.net>...
Welcome to Python.

Others have suggested approaches which attempt to read the whole file
into memory, but may succeed very slowly or not at all in the event
that you have files that are larger than your machine's physical
memory; here's a slightly more robust approach:

num_lines = 0
f = file('path_and_file_name')
for line in f:
num_lines += 1
f.close()

HTH,
John

You can do a one-liner without reading the whole file at once ;-)

reduce(lambda x,y: x+1, file('/path/and/filename').xreadlines(), 0)

Regards,
Bengt Richter