regular expression in strings

[David Bear]

I'm trying to understand how regex's are interpreted out of strings
objects. for example, If I have a string that has newline chars in
it, how can I get a re.split to respect where the newlines are?
[color=blue][color=green][color=darkred]
>>> bs = 'in the begining, \n there were new lines, and in the end \nin lines'
>>> re.split('^in', bs)[/color][/color][/color]
['', ' the begining, \n there were new lines, and in the end \nin lines'][color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

I want to split the string bs. a '^in' should have also match \nin
where \n is the newline char.

Ultimately I have a large string buffer that I want to split at each
occurence of a particular regular expression, where the result
contains everything from the occurence of the regex till the end of
the 'line'

any pointers?

David Bear
phone: 480-965-8257
fax: 480-965-9189
College of Public Programs/ASU
Wilson Hall 232
Tempe, AZ 85287-0803
"Beware the IP portfolio, everyone will be suspect of trespassing"

[David M. Cooke]

Re: regular expression in strings

At some point, David Bear <david.bear@asu .edu> wrote:
[color=blue]
> I'm trying to understand how regex's are interpreted out of strings
> objects. for example, If I have a string that has newline chars in
> it, how can I get a re.split to respect where the newlines are?
>[color=green][color=darkred]
>>>> bs = 'in the begining, \n there were new lines, and in the end \nin lines'
>>>> re.split('^in', bs)[/color][/color]
> ['', ' the begining, \n there were new lines, and in the end \nin lines'][color=green][color=darkred]
>>>>[/color][/color]
>
> I want to split the string bs. a '^in' should have also match \nin
> where \n is the newline char.[/color]

Just amounts to reading the documentation for the re module; what you want is[color=blue][color=green][color=darkred]
>>> re.split('(?m)^ in', bs)[/color][/color][/color]
['', ' the begining, \n there were new lines, and in the end \n', ' lines']

The (?m) construct says 'set flag re.M for this expression', where
re.M == re.MULTILINE is the flag to have ^ match the beginning of
the string and the beginning of each line (similiar for $).

It's a bit clearer with compiled patterns:[color=blue][color=green][color=darkred]
>>> pat = re.compile('^in ', re.MULTILINE)
>>> pat.split(bs)[/color][/color][/color]
['', ' the begining, \n there were new lines, and in the end \n', ' lines']

--
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|David M. Cooke
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