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Re: Regex: Perl to Python

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On Mon, Mar 7, 2016 at 3:38 PM, Fillmore <fillmore_remove@hotmail.com> wrote:
> pattern = re.compile(r"(\d+)\t(.+)$")
> with open(fields_Indexfile,mode="rt",encoding='utf-8') as headerfile:
>     for line in headerfile:
>         #sys.stdout.write(line)
>         m = pattern.match(line)
>         print(m.group(0))
>     headerfile.close()
>
> but I must be getting something fundamentally wrong because:
>
> Traceback (most recent call last):
>   File "./slicer.py", line 30, in <module>
>     print(m.group(0))
> AttributeError: 'NoneType' object has no attribute 'group'
>
>
>  why is 'm' a None?

When the regex doesn't match, Python gives you back None instead of a
match object. Your Perl code has an 'if' to guard that; you can do the
same thing:

if m:
    print(m.group(0))

ChrisA

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Thread

Regex: Perl to Python Fillmore <fillmore_remove@hotmail.com> - 2016-03-06 23:38 -0500
  Re: Regex: Perl to Python Chris Angelico <rosuav@gmail.com> - 2016-03-07 15:45 +1100
  Re: Regex: Perl to Python Terry Reedy <tjreedy@udel.edu> - 2016-03-06 23:48 -0500
    Re: Regex: Perl to Python Rustom Mody <rustompmody@gmail.com> - 2016-03-06 21:53 -0800
    Re: Regex: Perl to Python Rustom Mody <rustompmody@gmail.com> - 2016-03-06 21:53 -0800
  Re: Regex: Perl to Python Peter Otten <__peter__@web.de> - 2016-03-07 08:48 +0100
  Re: Regex: Perl to Python Fillmore <fillmore_remove@hotmail.com> - 2016-03-07 07:50 -0500

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