regex that is equivalent to perl's syntax

Tim Chase python.list at tim.thechases.com
Mon Nov 12 16:51:20 CET 2007


> does python's re library have a similar capability of the perls
> regular expression to
> search for pattern that appears a variable number of times within the
> lower and upper bounds given? For example, what is the python's
> equivalent to the following perl's search string?
> m/^\S{1,8}\.\S{0,3}/
> which seeks to find all strings with 8 characters followed by a dot
> and then three more characters as in filename.txt
> 
> Actually, i need to find a pattern such as ABCDXLMNO with the
> character X
> repeated 5 to 8 times.

You're interested in the "re" library, documented here[1] which, 
astonishingly, is the first result when I google for

   python re library

In your particular case, the syntax is identical to perl 
regexps[2] (the 2nd hit Google returns with the above query)

   import re
   r1 = re.compile(r'\S{1,8}\.\S{0,3}')
   r2 = re.compile(r'ABCDX{5,8}LMNO')
   # use r1/r2 for matching, substitution, taking over the world

Note the use of "raw" strings (doesn't matter so much in the 2nd 
version, as there's nothing escaped), as suggested in the docs.

-tkc


[1] http://docs.python.org/lib/module-re.html
[2] http://docs.python.org/lib/re-syntax.html








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