Re: OT: Python help

["Peter Westlake" <peter.westlake@pobox.com>]

On Tue, 20 Jul 2010 16:58 +0530, "Puneeth" <punchagan@gmail.com> wrote:
> On Tue, Jul 20, 2010 at 4:50 PM, Puneeth <punchagan@gmail.com> wrote:
> > On Tue, Jul 20, 2010 at 4:43 PM, Carsten Dominik <dominik@uva.nl> wrote:
> >> Please show me the full line of code, I am currently editing a python script
> >> without any knowledge of python...
> >
> > my_string = "Hello\nWorld"
> > my_new_string = my_string.replace("\n", "\n> ")
> 
> Sorry, this code (obviously) doesn't prepend ">" to the first line
> Add this line to do that.
> 
> my_new_string = "> " + my_new_string

Here's a Pythonic way to do it, tested:

  import re

  my_string = "Hello\nWorld"
  pattern = re.compile('^',re.MULTILINE)
  my_new_string = re.sub(pattern, '> ', my_string)

This still might not be quite right, as it will turn "Hello\nWorld\n"
into "> Hello\n> World\n> ". Avoid that by using a negative lookahead
for the end of the string:

  my_string = "Hello\n\nWorld\n"
  pattern = re.compile('^(?!\Z)',re.MULTILINE)
  my_new_string = re.sub(pattern, '> ', my_string)
  print my_new_string

gives:

  > Hello
  >
  > World


Peter.