This snippet defines a function patfilter(pattern, rule, sequence) which implements filtering a sequence of strings according to various criteria. The output is either a subsequence of strings, or a sequence of match objects.

#!/usr/bin/env python
# Copyright (c) Gribouillis at
import re 
from fnmatch import fnmatch ,fnmatchcase ,filter as fnfilter 
try :# python 2.5
  from itertools import ifilter as filter 
except ImportError :# python 3.0

def patfilter (pattern ,rule ,sequence ):
  """patfilter(pattern, rule, sequence_of_strings) --> sequence
     patfilter.rules() -> the set of accepted rules
    pattern  <- a regular expression (re object or string)
    rule     <- a string
    sequence <- an iterable sequence of strings
    depending on the rule
    "m"    -> the strings in the sequence which match the pattern
    "s"    -> the strings which contain the pattern
    "!m"   -> the strings which don't match the pattern
    "!s"   -> the strings which don't contain the pattern
    "@m"   -> the match objects for all the matches in the sequence
    "@s"   -> the match objects for at most one search per string
    "@a"   -> the match objects for all the searches in the sequence
                   (subsequent match objects may concern the same string)
    "f"   -> the strings which match the pattern in the sense of
                     the fnmatch module (*)
    "!f"  -> the strings which dont fnmatch the pattern (*)
    "F"   -> the string which fnmatch, case sensitive (*)
    "!F"  -> the strings which don't fnmatch, case sensitive (*)

  (*) the pattern must be a string for fnmatch rules.
  if rule not in _PatFilter ._rules :
    raise ValueError("Unknown rule.")
  if rule [-1 ]not in "fF":
    pattern =re .compile (pattern )
  return getattr (_PatFilter ,_PatFilter ._rules [rule ])(pattern ,sequence )

def rules ():
  "rules() -> the set of rules accepted by patselect."
  return set (_PatFilter ._rules )

patfilter .rules =rules 

__all__ =["patselect","rules"]

class _PatFilter (object ):
  _rules ={
  def matches (pat ,seq ):
    return filter (None ,(pat .match (x )for x in seq ))
  def searches (pat ,seq ):
    return filter (None ,(pat .search (x )for x in seq ))
  def allsearches (pat ,seq ):
    return (mo for x in seq for mo in pat .finditer (x ))
  def match (pat ,seq ):
    return filter (lambda x :pat .match (x ),seq )
  def search (pat ,seq ):
    return filter (lambda x :pat .search (x ),seq )
  def nomatch (pat ,seq ):
    return filter (lambda x :not pat .match (x ),seq )
  def nosearch (pat ,seq ):
    return filter (lambda x :not pat .search (x ),seq )
  def fnmatch (pat ,seq ):
    return fnfilter (seq ,pat )
  def nofnmatch (pat ,seq ):
    return filter (lambda x :not fnmatch (x ,pat ),seq )
  def fnmatchcase (pat ,seq ):
    return filter (lambda x :fnmatchcase (x ,pat ),seq )
  def nofnmatchcase (pat ,seq ):
    return filter (lambda x :not fnmatchcase (x ,pat ),seq )

if __name__ =="__main__":
  L =list (open (__file__ ))
  for r in patfilter .rules ():
    pat ="*seq*"if r [-1 ]in "fF"else "seq"
    print ("======= RULE '%s' ==== PATTERN '%s' ===="%(r ,pat ))
    for item in patfilter (pat ,r ,L ):
      if r [0 ]=="@":
        item =item .string 
      print (item .rstrip ())

For example

lines = iter(open(filename))  # this is a sequence of strings (here,  an iterator)
for line in patfilter("<a\s*href", "s", lines): # filter the lines which contain a href


filenames = os.listdir(os.getcwd())
for name in patfilter("*.pyc", "f", filenames): # filter the compiled python files