Extract the numeric and alphabetic part from an alphanumeric string

Peter Brett peter at peter-b.co.uk
Mon Aug 3 17:31:09 CEST 2009


Sandhya Prabhakaran <sandhyaprabhakaran at gmail.com> writes:

> Hi,
>
> I have a string as str='123ACTGAAC'.
>
> I need to extract the numeric part from the alphabetic part which I
> did using
>>>>numer=re.findall(r'\d+',str)
>>>>numer
> 123
>
> To get the alphabetic part, I could do
>>>>alpha=str.replace('123','')
>>>>alpha
> ACTGAAC
> But when I give
>>>>alpha=str.replace(numer,'')
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> TypeError: expected a character buffer object
>
> How do I blank out the initial numeric part so as to get just the
> alphabetic part. The string is always in the same format.

Firstly, you really should read the Regular Expression HOWTO:

  http://docs.python.org/howto/regex.html#regex-howto

Secondly, is this what you wanted to do?

  >>> p = re.compile(r'^\d+')
  >>> p.sub('', '123ACTGAAC')
  'ACTGAAC'

Regards,

                                       Peter

-- 
Peter Brett <peter at peter-b.co.uk>
Remote Sensing Research Group
Surrey Space Centre



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