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replace words

Paul McGuire ptmcg at austin.rr.com
Wed Oct 26 15:26:39 EDT 2005 
hagai26 at gmail.com wrote:
> What is the way for replacing in a string from . to . the sentence?
> for example:
> "been .taken.  it may be .left. there,
> even if the .live coals were not. cleared"
> I want to do this-> replace(\.(.*)\.,\.start (1) end\.)
> result:
> "been .start taken end.  it may be .start left end. there,
> even if the .start live coals were not end. cleared"

Here is a pyparsing version. Yes, it is more verbose, and, being pure
Python, is not as fast as regexp.  But the syntax is very easy to
follow and maintain, and the parse actions can add quite a bit of
additional logic during the parsing process (for example, rejecting dot
pairs that span line breaks).

-- Paul


from pyparsing import Literal,SkipTo

data = """been .taken.  it may be .left. there,
even if the .live coals were not. cleared"""

DOT = Literal(".")

# expression to match, comparable to regexp r"\.(.*?)\."
dottedText = DOT + SkipTo(DOT).setResultsName("body") + DOT

# action to run when match is found - return modified text
def enhanceDots( st, loc, tokens):
    return ".start " + tokens.body + " end."
dottedText.setParseAction( enhanceDots )

# transform the string
print dottedText.transformString( data )


Gives:
been .start taken end.  it may be .start left end. there,
even if the .start live coals were not end. cleared
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