Re: re.sub and named groups
Book recommendation: _Mastering Regular Expressions_, Jeffrey Friedl -- Aahz (a...@pythoncraft.com) * http://www.pythoncraft.com/ I wholeheartedly second this! The third edition is out now. -- http://mail.python.org/mailman/listinfo/python-list
Re: re.sub and named groups
On Feb 4, 10:51 am, Emanuele D'Arrigo man...@gmail.com wrote:
Hi everybody,
I'm having a ball with the power of regular expression
Don't forget the ball you can have with the power of ordinary Python
strings, string methods, and string interpolation!
originalString = spam:%(first)s ham:%(second)s
print originalString % { first : foo , second : }
prints
spam:foo ham:
with far fewer surprises and false steps. (Note: Py3K supports this
same feature, but with different interpolation syntax, which I have
not learned yet.)
Book recommendation: Text Processing in Python, by David Mertz (free
online - http://gnosis.cx/TPiP/), in which David advises against
dragging out the RE heavy artillery until you've at least thought
about using ordinary string methods.
-- Paul
--
http://mail.python.org/mailman/listinfo/python-list
Re: re.sub and named groups
On Wed, 11 Feb 2009 21:05:53 -, Paul McGuire pt...@austin.rr.com wrote: On Feb 4, 10:51 am, Emanuele D'Arrigo man...@gmail.com wrote: Hi everybody, I'm having a ball with the power of regular expression Don't forget the ball you can have with the power of ordinary Python strings, string methods, and string interpolation! So the moral of this story is take a ball of strings with you for when you get lost in regular expressions. -- Rhodri James *-* Wildebeeste Herder to the Masses -- http://mail.python.org/mailman/listinfo/python-list
Re: re.sub and named groups
In article 4c7158d2-5663-46b9-b950-be81bd799...@z6g2000pre.googlegroups.com, Emanuele D'Arrigo man...@gmail.com wrote: I'm having a ball with the power of regular expression but I stumbled on something I don't quite understand: Book recommendation: _Mastering Regular Expressions_, Jeffrey Friedl -- Aahz (a...@pythoncraft.com) * http://www.pythoncraft.com/ Weinberg's Second Law: If builders built buildings the way programmers wrote programs, then the first woodpecker that came along would destroy civilization. -- http://mail.python.org/mailman/listinfo/python-list
re.sub and named groups
Hi everybody, I'm having a ball with the power of regular expression but I stumbled on something I don't quite understand: theOriginalString = spam:(?Pfirst.*) ham:(?Psecond.*) aReplacementPattern = \(\?Pfirst.*\) aReplacementString= foo re.sub(aReplacementPattern , aReplacementString, theOriginalString) results in : spam:foo instead, I was expecting: spam:foo ham: Why is that? Thanks for your help! Manu -- http://mail.python.org/mailman/listinfo/python-list
Re: re.sub and named groups
Emanuele D'Arrigo wrote: Hi everybody, I'm having a ball with the power of regular expression but I stumbled on something I don't quite understand: theOriginalString = spam:(?Pfirst.*) ham:(?Psecond.*) aReplacementPattern = \(\?Pfirst.*\) aReplacementString= foo re.sub(aReplacementPattern , aReplacementString, theOriginalString) results in : spam:foo instead, I was expecting: spam:foo ham: Why is that? Thanks for your help! The quantifiers eg * are normally greedy; they try to match as much as possible. Therefore .* matches: spam:(?Pfirst.*) ham:(?Psecond.*) ^ You could use the lazy form *? which tries to match as little as possible, eg \(\?Pfirst.*?\) where the .*? matches: spam:(?Pfirst.*) ham:(?Psecond.*) ^^ giving spam:foo ham:(?Psecond.*). -- http://mail.python.org/mailman/listinfo/python-list
Re: re.sub and named groups
On Feb 4, 5:17 pm, MRAB goo...@mrabarnett.plus.com wrote: You could use the lazy form *? which tries to match as little as possible, eg \(\?Pfirst.*?\) where the .*? matches: spam:(?Pfirst.*) ham:(?Psecond.*) giving spam:foo ham:(?Psecond.*). A-ha! Of course! That makes perfect sense! Thank you! Problem solved! Ciao! Manu -- http://mail.python.org/mailman/listinfo/python-list
Re: re.sub and named groups
Hi everybody, I'm having a ball with the power of regular expression but I stumbled on something I don't quite understand: theOriginalString = spam:(?Pfirst.*) ham:(?Psecond.*) aReplacementPattern = \(\?Pfirst.*\) aReplacementString= foo re.sub(aReplacementPattern , aReplacementString, theOriginalString) results in : spam:foo instead, I was expecting: spam:foo ham: Why is that? Thanks for your help! Manu I think that .* in your replacement pattern matches .*) ham:(?Psecond.* in your original string which seems correct for a regexp. Perhaps you should try aReplacementPattern = \(\?Pfirst\.\*\) or use replace() since your replacement pattern is not a regexp anymore. Sebastien -- http://mail.python.org/mailman/listinfo/python-list
