passing multiple strings to string.find()

Re: passing multiple strings to string.find()


"hokiegal99 " <hokiegal99@vt. edu> wrote in message
news:3F331A9B.9 [email protected].. .[color=blue]
> How do I say:
>
> x = string.find(fil es, 'this', 'that', 'the-other')
>
> currently I have to write it like this to make it work:
>
> x = string.find(fil es, 'this')
> y = string.find(fil es, 'that')
> z = string.find(fil es, 'the-other')[/color]

Try this:

x, y, z = map(files.find, ['this', 'that', 'the-other'])

or, if you're just trying to find the first match:

re.search('this |that|the-other', files).start()


OTOH, you've hinted at an application that may not
appropriate for multiple string searches. Instead, look
at building a dictionary or list of files -- they are most
easily searched and better suited for associating other
data such as file sizes, etc.




Raymond Hettinger

Re: passing multiple strings to string.find()

On Thu, 07 Aug 2003 23:35:55 -0400, hokiegal99 <hokiegal99@vt. edu> wrote:
[color=blue]
>How do I say:
>
>x = string.find(fil es, 'this', 'that', 'the-other')
>
>currently I have to write it like this to make it work:
>
>x = string.find(fil es, 'this')
>y = string.find(fil es, 'that')
>z = string.find(fil es, 'the-other')
>[/color]

You might try the re module, e.g.,
[color=blue][color=green][color=darkred]
>>> import re
>>> rxo = re.compile(r'th is|that|the-other')
>>> pos = 0
>>> while 1:[/color][/color][/color]
... m = rxo.search(' Find this or the-other or that and this.', pos)
... if not m: break
... print '%4s: %s' % (m.start(), m.group())
... pos = m.end()
...
6: this
14: the-other
27: that
36: this

If some search strings have a common prefix, you'll have to put
the longest first in the regex, since re grabs the first match it sees.

Regards,
Bengt Richter

Re: passing multiple strings to string.find()

[Fredrik Lundh]
[color=blue]
> Francois Pinard wrote:[/color]
[color=blue][color=green]
> > Given the above,
> >
> > build_regexp(['this', 'that', 'the-other'])
> >
> > yields the string 'th(?:is|at|e\\-other)', which one may choose to
> > `re.compile' before use.[/color][/color]
[color=blue]
> the SRE compiler looks for common prefixes, so "th(?:is|at |e\\-other)" is
> no different from "this|that| the-other" on the engine level.[/color]

Thanks for the note. So the `build_regexp' function is not useful after
all. It was indirectly written around a speed problem in the GNU regexp
engine, but seemingly, the Python regexp engine knows better already. AsI
wrote earlier, I first saw Emacs Lisp `regexp-opt' used within `enscript'..

A speed comparison between both methods shows that they are fairly
equivalent. A small difference is that `build_regexp', given that one of
the word is a prefix of another, automatically recognises the longest one,
while a naive regexp of '|'.join(words) recognises whatever happens to be
listed first. Of course, this is easily solved by sorting, then reversing
the word list before producing the naive regexp.

--
François Pinard http://www.iro.umontreal.ca/~pinard