Python editing .txt file

[MRAB]

187braintrust at berkeley.edu wrote:
>     From: MRAB <python at mrabarnett.plus.com
>     <mailto:python at mrabarnett.plus.com>>
>     To: python-list at python.org <mailto:python-list at python.org>
>     Date: Wed, 16 Jun 2010 03:06:58 +0100
>     Subject: Re: Python editing .txt file
>     187braintrust at berkeley.edu <mailto:187braintrust at berkeley.edu> wrote:
> 
>         I am trying to write a program in Python that will edit .txt log
>         files that contain regression output from R.  Any thoughts or
>         suggestions would be greatly appreciated.  
> 
>      
>     How's this:
> 
>     input_file = open(input_path)
>     output_file = open(output_path, "w")
>     for line in input_file:
>        if line.startswith("factor("):
>            open_paren = line.find("(")
>            close_paren = line.find(")")
>            variable = line[open_paren + 1 : close_paren]
>            output_file.write("*** Factors for %s ***\n" % variable)
>            prefix = line[ : close_paren + 1]
>            while line.startswith(prefix):
>                line = input_file.readline()
>        output_file.write(line)
>     input_file.close()
>     output_file.close() 
> 
> 
> Thank you very much for your reply.  This code works perfectly, except 
> that the "line = input_file.readline()" part causes an error: 
> "ValueError: Mixing iteration and read methods would lose data."  I've 
> been working on figuring out a work around.  Do you have any ideas?
> 
You could try replacing:

     line = input_file.readline()

with:

     line = input_file.next()