Regular Expression IGNORECASE different for findall and split?

[Chris]

hello,
I have question about the re.I option for Regular Expressions:
[color=blue][color=green][color=darkred]
>>> import re
>>> re.findall('x', '1x2X3', re.I)[/color][/color][/color]
['x', 'X']

as expected finds both lower and uppercase x

[color=blue][color=green][color=darkred]
>>> re.split('x', '1x2X3', re.I)[/color][/color][/color]
['1', '2X3'][color=blue][color=green][color=darkred]
>>> re.split('x', '1x2X3')[/color][/color][/color]
['1', '2X3']

I expected ['1', '2', '3'] but in this case re.I bahaves exactly as not
present at all...

Is that an expected behaviour or a fault?
Running Python 2.4.1 on Windows XP

thanks for any hint
chris

[Peter Otten]

Re: Regular Expression IGNORECASE different for findall and split?

Chris wrote:
[color=blue][color=green][color=darkred]
> >>> re.split('x', '1x2X3', re.I)[/color][/color]
> ['1', '2X3'][/color]

[color=blue]
> I expected ['1', '2', '3'] but in this case re.I bahaves exactly as not
> present at all...[/color]
[color=blue]
> Is that an expected behaviour or a fault?[/color]

This is expected:
[color=blue][color=green][color=darkred]
>>> help(re.split)[/color][/color][/color]
Help on function split in module sre:

split(pattern, string, maxsplit=0)
Split the source string by the occurrences of the pattern,
returning a list containing the resulting substrings.

You are setting maxsplit to
[color=blue][color=green][color=darkred]
>>> re.I[/color][/color][/color]
2

Use re.compile() to get the desired behaviour:
[color=blue][color=green][color=darkred]
>>> re.compile("x", re.I).split("1x 2X3")[/color][/color][/color]
['1', '2', '3']

Peter

[Chris]

__dict__ of object, Was: Regular Expression IGNORECASE differentfor findall and split?

Peter Otten wrote:[color=blue]
> Chris wrote:
>
>[color=green][color=darkred]
>> >>> re.split('x', '1x2X3', re.I)[/color]
>>['1', '2X3'][/color]
>
>
>[color=green]
>>I expected ['1', '2', '3'] but in this case re.I bahaves exactly as not
>>present at all...[/color]
>
>
>[color=green]
>>Is that an expected behaviour or a fault?[/color]
>
>
> This is expected:
>
>[color=green][color=darkred]
>>>>help(re.spl it)[/color][/color]
>
> Help on function split in module sre:
>
> split(pattern, string, maxsplit=0)
> Split the source string by the occurrences of the pattern,
> returning a list containing the resulting substrings.
>
> You are setting maxsplit to
>
>[color=green][color=darkred]
>>>>re.I[/color][/color]
>
> 2
>
> Use re.compile() to get the desired behaviour:
>
>[color=green][color=darkred]
>>>>re.compile( "x", re.I).split("1x 2X3")[/color][/color]
>
> ['1', '2', '3']
>
> Peter[/color]

thanks, I should read the docs but

but more of a basic question following, I was doing the following before:

method = 'split' # came from somewhere else of course
result = re.__dict__[method].(REGEX, TXT)

precompiling the regex

r = compile(REGEX)

does give an regex object which has the needed methods

print dir(r)
['__copy__', '__deepcopy__', 'findall', 'finditer', 'match', 'scanner',
'search', 'split', 'sub', 'subn']

but how do I evaluate them without explicitly calling them?

result = r.__???MAGIC??? __[method](TXT)

obviously I am not a Python pro ;)

thanks
chris

[Steven Bethard]

Re: __dict__ of object, Was: Regular Expression IGNORECASE differentfor findall and split?

Chris wrote:[color=blue]
> but more of a basic question following, I was doing the following before:
>
> method = 'split' # came from somewhere else of course
> result = re.__dict__[method].(REGEX, TXT)
>
> precompiling the regex
>
> r = compile(REGEX)
>
> does give an regex object which has the needed methods
>
> print dir(r)
> ['__copy__', '__deepcopy__', 'findall', 'finditer', 'match',
> 'scanner', 'search', 'split', 'sub', 'subn']
>
> but how do I evaluate them without explicitly calling them?
>
> result = r.__???MAGIC??? __[method](TXT)
>
> obviously I am not a Python pro ;)[/color]

Use getattr:

method = 'split'
result = getattr(re.comp ile(REGEX), method)(TXT)

HTH,

STeVe

[Fredrik Lundh]

Re: __dict__ of object,

Chris <c@cdot.de> wrote:
[color=blue]
> but more of a basic question following, I was doing the following before:
>
> method = 'split' # came from somewhere else of course
> result = re.__dict__[method].(REGEX, TXT)
>
> precompiling the regex
>
> r = compile(REGEX)
>
> does give an regex object which has the needed methods
>
> print dir(r)
> ['__copy__', '__deepcopy__', 'findall', 'finditer', 'match', 'scanner',
> 'search', 'split', 'sub', 'subn']
>
> but how do I evaluate them without explicitly calling them?
>
> result = r.__???MAGIC??? __[method](TXT)
>
> obviously I am not a Python pro ;)[/color]

I really don't understand why you think you have to write
your RE code that way, but the mechanism you're looking
for is getattr:

result = getattr(r, method)(TXT)

</F>

[Chris]

Re: __dict__ of object, Was: Regular Expression IGNORECASE differentforfin dall and split?

Fredrik Lundh wrote:[color=blue]
> Chris <c@cdot.de> wrote:
>
>[color=green]
>>but more of a basic question following, I was doing the following before:
>>
>>method = 'split' # came from somewhere else of course
>>result = re.__dict__[method].(REGEX, TXT)
>>
>>precompilin g the regex
>>
>>r = compile(REGEX)
>>
>>does give an regex object which has the needed methods
>>
>>print dir(r)
>>['__copy__', '__deepcopy__', 'findall', 'finditer', 'match', 'scanner',
>>'search', 'split', 'sub', 'subn']
>>
>>but how do I evaluate them without explicitly calling them?
>>
>>result = r.__???MAGIC??? __[method](TXT)
>>
>>obviously I am not a Python pro ;)[/color]
>
>
> I really don't understand why you think you have to write
> your RE code that way, but the mechanism you're looking
> for is getattr:
>
> result = getattr(r, method)(TXT)
>[/color]

thanks (also to Steven) for the info, that is exactly what i was looking
for.

reason is that I built a small UI in which the user may choose if he
want to do a split, findall (and maybe later others like match or
search). So the method name comes in "from the UI". I could of course
use if/elif/else blocks but thought getattr should be shorter and
easier. I was not really aware of getattr which I was looking for on
other occations before...

chris

[Mike Meyer]

Re: __dict__ of object, Was: Regular Expression IGNORECASEdiffe rentfor findall and split?

Chris <c@cdot.de> writes:[color=blue]
> Fredrik Lundh wrote:[color=green]
>> Chris <c@cdot.de> wrote:
>>[color=darkred]
>>>but more of a basic question following, I was doing the following before:
>>>
>>>method = 'split' # came from somewhere else of course
>>>result = re.__dict__[method].(REGEX, TXT)
>>>
>>>precompili ng the regex
>>>
>>>r = compile(REGEX)
>>>
>>>does give an regex object which has the needed methods
>>>
>>>print dir(r)
>>>['__copy__', '__deepcopy__', 'findall', 'finditer', 'match', 'scanner',
>>>'search', 'split', 'sub', 'subn']
>>>
>>>but how do I evaluate them without explicitly calling them?
>>>
>>>result = r.__???MAGIC??? __[method](TXT)
>>>
>>>obviously I am not a Python pro ;)[/color]
>> I really don't understand why you think you have to write
>> your RE code that way, but the mechanism you're looking
>> for is getattr:
>> result = getattr(r, method)(TXT)
>>[/color]
>
> thanks (also to Steven) for the info, that is exactly what i was
> looking for.
>
> reason is that I built a small UI in which the user may choose if he
> want to do a split, findall (and maybe later others like match or
> search). So the method name comes in "from the UI". I could of course
> use if/elif/else blocks but thought getattr should be shorter and
> easier. I was not really aware of getattr which I was looking for on
> other occations before...[/color]

So why is the UI returning strings, instead of code objects of some
kind?

<mike
--
Mike Meyer <mwm@mired.or g> http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

[Chris]

Re: __dict__ of object, Was: Regular Expression IGNORECASE differentforfin dall and split?

Mike Meyer wrote:[color=blue]
> Chris <c@cdot.de> writes:
>[color=green]
>>Fredrik Lundh wrote:
>>[color=darkred]
>>>Chris <c@cdot.de> wrote:
>>>
>>>
>>>>but more of a basic question following, I was doing the following before:
>>>>
>>>>method = 'split' # came from somewhere else of course
>>>>result = re.__dict__[method].(REGEX, TXT)
>>>>
>>>>precompilin g the regex
>>>>
>>>>r = compile(REGEX)
>>>>
>>>>does give an regex object which has the needed methods
>>>>
>>>>print dir(r)
>>>>['__copy__', '__deepcopy__', 'findall', 'finditer', 'match', 'scanner',
>>>>'search', 'split', 'sub', 'subn']
>>>>
>>>>but how do I evaluate them without explicitly calling them?
>>>>
>>>>result = r.__???MAGIC??? __[method](TXT)
>>>>
>>>>obviously I am not a Python pro ;)
>>>
>>>I really don't understand why you think you have to write
>>>your RE code that way, but the mechanism you're looking
>>>for is getattr:
>>> result = getattr(r, method)(TXT)
>>>[/color]
>>
>>thanks (also to Steven) for the info, that is exactly what i was
>>looking for.
>>
>>reason is that I built a small UI in which the user may choose if he
>>want to do a split, findall (and maybe later others like match or
>>search). So the method name comes in "from the UI". I could of course
>>use if/elif/else blocks but thought getattr should be shorter and
>>easier. I was not really aware of getattr which I was looking for on
>>other occations before...[/color]
>
>
> So why is the UI returning strings, instead of code objects of some
> kind?
>
> <mike[/color]

it is a simple ajax call to a python server doing the re. maybe a bit
contrived but it was nice to try python/ajax on a for me useful app to
enable easy tryout of regular expressions. if you are interested check
out http://cthedot.de/retest/

chris