Defining re pattern for matching list of numbers

[jorma kala]

Hi,

I'm trying to write a re pattern to match a list of one or more numbers, each number is in the range of 1-15 value and the numbers are separated by spaces (but there are no spaces at the beginning and end of the string). For instance:

 

"3"

"1 14 8"

 

but not:

 

"22"

" 5 11"

 

I've come up with something like this

 

re.compile("^((([1-9])|(1[0-8]))( +(?=[1-9]))*)+$")

 

but I can't believe this has to be so complicated.

Does anyone know some simpler re pattern to match this kind of string

Many thanks

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[Chris Rebert-6]

On Fri, Nov 6, 2009 at 8:04 AM, jorma kala <jjkk73@...> wrote:

> Hi,
> I'm trying to write a re pattern to match a list of one or more numbers,
> each number is in the range of 1-15 value and the numbers are separated by
> spaces (but there are no spaces at the beginning and end of the string). For
> instance:
>
> "3"
> "1 14 8"
>
> but not:
>
> "22"
> " 5 11"
>
> I've come up with something like this
>
> re.compile("^((([1-9])|(1[0-8]))( +(?=[1-9]))*)+$")
>
> but I can't believe this has to be so complicated.

Your format seems so simple I have to ask why you're using regexes in
the first place.

try:
    nums = [int(num) for num in line.split(" ")]
except ValueError:
    print "Invalid input"

for num in nums:
    if num < 1 or num > 15:
        raise ValueError, "Number present which is outside of valid range"

Cheers,
Chris
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[jorma kala]

Thanks for your reply.
But I need to use a regex; my program deals with a large number of  patterns, and I want to treat them in a uniform way (through regex).

On 11/6/09, Chris Rebert <clp2@...> wrote:

On Fri, Nov 6, 2009 at 8:04 AM, jorma kala <jjkk73@...> wrote:
> Hi,
> I'm trying to write a re pattern to match a list of one or more numbers,
> each number is in the range of 1-15 value and the numbers are separated by
> spaces (but there are no spaces at the beginning and end of the string). For
> instance:
>
> "3"
> "1 14 8"
>
> but not:
>
> "22"
> " 5 11"
>
> I've come up with something like this
>
> re.compile("^((([1-9])|(1[0-8]))( +(?=[1-9]))*)+$")
>
> but I can't believe this has to be so complicated.


Your format seems so simple I have to ask why you're using regexes in
the first place.

try:
    nums = [int(num) for num in line.split(" ")]
except ValueError:
    print "Invalid input"

for num in nums:
    if num < 1 or num > 15:
        raise ValueError, "Number present which is outside of valid range"

Cheers,
Chris

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[Steven D'Aprano-7]

On Fri, 06 Nov 2009 10:16:31 -0800, Chris Rebert wrote:

> Your format seems so simple I have to ask why you're using regexes in
> the first place.

Raymond Hettinger has described some computing techniques as "code
prions" -- programming advice or techniques which are sometimes useful
but often actively harmful.

http://www.mail-archive.com/python-list%40python.org/msg262651.html

As useful as regexes are, I think they qualify as code prions too: people
insist on using them in production code, even when a simple string method
or function would do the job far more efficiently and readably.



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