re Insanity

[Tim Daneliuk]

For some reason, I am having the hardest time doing something that should
be obvious. (Note time of posting ;)

Given an arbitrary string, I want to find each individual instance of
text in the form: "[PROMPT:optional text]"

I tried this:

y=re.compile(r' \[PROMPT:.*\]')

Which works fine when the text is exactly "[PROMPT:whatever]" but
does not match on:

"something [PROMPT:foo] something [PROMPT:bar] something ..."

The overall goal is to identify the beginning and end of each [PROMPT...]
string in the line.

Ideas anyone?
--
----------------------------------------------------------------------------
Tim Daneliuk tundra@tundrawa re.com
PGP Key: http://www.tundraware.com/PGP/

[Fredrik Lundh]

Re: Insanity

Tim Daneliuk wrote:
[color=blue]
> Given an arbitrary string, I want to find each individual instance of
> text in the form: "[PROMPT:optional text]"
>
> I tried this:
>
> y=re.compile(r' \[PROMPT:.*\]')
>
> Which works fine when the text is exactly "[PROMPT:whatever]"[/color]

didn't you leave something out here? "compile" only compiles that pattern;
it doesn't match it against your string...
[color=blue]
> but does not match on:
>
> "something [PROMPT:foo] something [PROMPT:bar] something ..."
>
> The overall goal is to identify the beginning and end of each [PROMPT...]
> string in the line.[/color]

if the pattern can occur anywhere in the string, you need to use "search",
not "match". if you want multiple matches, you can use "findall" or, better
in this case, "finditer":

import re

s = "something [PROMPT:foo] something [PROMPT:bar] something"

for m in re.finditer(r'\[PROMPT:[^]]*\]', s):
print m.span(0)

prints

(10, 22)
(33, 45)

which looks reasonably correct.

(note the "[^x]*x" form, which is an efficient way to spell "non-greedy match"
for cases like this)

</F>

[Duncan Booth]

Re: re Insanity

Tim Daneliuk wrote:
[color=blue]
>
> I tried this:
>
> y=re.compile(r' \[PROMPT:.*\]')
>
> Which works fine when the text is exactly "[PROMPT:whatever]" but
> does not match on:
>
> "something [PROMPT:foo] something [PROMPT:bar] something ..."
>
> The overall goal is to identify the beginning and end of each [PROMPT...]
> string in the line.
>[/color]

The answer sort of depends on exactly what can be in your optional text:
[color=blue][color=green][color=darkred]
>>> import re
>>> s = "something [PROMPT:foo] something [PROMPT:bar] something ..."
>>> y=re.compile(r' \[PROMPT:.*\]')
>>> y.findall(s)[/color][/color][/color]
['[PROMPT:foo] something [PROMPT:bar]'][color=blue][color=green][color=darkred]
>>> y=re.compile(r' \[PROMPT:.*?\]')
>>> y.findall(s)[/color][/color][/color]
['[PROMPT:foo]', '[PROMPT:bar]'][color=blue][color=green][color=darkred]
>>> y=re.compile(r' \[PROMPT:[^]]*\]')
>>> y.findall(s)[/color][/color][/color]
['[PROMPT:foo]', '[PROMPT:bar]'][color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

..* will match as long a string as possible.

..*? will match as short a string as possible. By default this won't match
any newlines.

[^]]* will match as long a string that doesn't contain ']' as possible.
This will match newlines.

[Aahz]

Re: re Insanity

In article <4ln9c2-0mh1.ln1@eskimo .tundraware.com >,
Tim Daneliuk <tundra@tundraw are.com> wrote:[color=blue]
>
>Given an arbitrary string, I want to find each individual instance of
>text in the form: "[PROMPT:optional text]"
>
>I tried this:
>
> y=re.compile(r' \[PROMPT:.*\]')
>
>Which works fine when the text is exactly "[PROMPT:whatever]" but
>does not match on:
>
> "something [PROMPT:foo] something [PROMPT:bar] something ..."
>
>The overall goal is to identify the beginning and end of each [PROMPT...]
>string in the line.
>
>Ideas anyone?[/color]

Yeah, read the Friedl book. (Okay, so that's not gonna help right now,
but trust me, if you're going to write lots of regexes, READ THAT BOOK.)
--
Aahz (aahz@pythoncra ft.com) <*> http://www.pythoncraft.com/

"19. A language that doesn't affect the way you think about programming,
is not worth knowing." --Alan Perlis

[Tim Daneliuk]

Re: re Insanity

Aahz wrote:[color=blue]
> In article <4ln9c2-0mh1.ln1@eskimo .tundraware.com >,
> Tim Daneliuk <tundra@tundraw are.com> wrote:
>[color=green]
>>Given an arbitrary string, I want to find each individual instance of
>>text in the form: "[PROMPT:optional text]"
>>
>>I tried this:
>>
>> y=re.compile(r' \[PROMPT:.*\]')
>>
>>Which works fine when the text is exactly "[PROMPT:whatever]" but
>>does not match on:
>>
>> "something [PROMPT:foo] something [PROMPT:bar] something ..."
>>
>>The overall goal is to identify the beginning and end of each [PROMPT...]
>>string in the line.
>>
>>Ideas anyone?[/color]
>
>
> Yeah, read the Friedl book. (Okay, so that's not gonna help right now,
> but trust me, if you're going to write lots of regexes, READ THAT BOOK.)[/color]

I've read significant parts of it. The problem is that I don't write
re often enough to recall all the subtle details ... plus I am getting
old and feeble... ;)

--
----------------------------------------------------------------------------
Tim Daneliuk tundra@tundrawa re.com
PGP Key: http://www.tundraware.com/PGP/