Looking for a Python Program/Tool That Will Add Line Numbers to a txt File

thebjorn BjornSteinarFjeldPettersen at gmail.com
Mon Feb 18 09:27:15 CET 2008

On Feb 15, 8:55 pm, Jeff Schwab <j... at schwabcenter.com> wrote:
> W. Watson wrote:
> > See Subject. It's a simple txt file, each line is a Python stmt, but I
> > need up to four digits added to each line with a space between the
> > number field and the text. Perhaps someone has already done this or
> > there's a source on the web for it. I'm not yet into files with Python.
> > A sudden need has burst upon me. I'm using Win XP.
> i = 0
> for line in sys.stdin:
>      i += 1
>      print i, line,
> Or if you want consistent alignment:
> i = 0
> for line in sys.stdin:
>      i += 1
>      print "%4s" % i, line,

I like your version best (it's very clean and easy to understand), but
here's a few more versions...

  from itertools import count

  for i, line in zip(count(1), open('filename.txt')):
      print i, line,

or with consistent alignment:

  for x in zip(count(1), open('filename.txt')):
      print "%4d %s" % x,

the latter version gives rise to a one-liner

  open('output.txt','w').writelines('%4d %s' % x for x in
zip(count(1), open('perms.py')))

but as I said, I like the simple for loop the best ;-)

-- bjorn

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