Need a specific sort of string modification. Can someone help?

[Nick Mellor]

Hi Sia,

Here's another variation. It's within my tolerance for readability :-) and also quick, if that's an issue. It does 100,000 of your longer string in a couple of seconds on my venerable laptop.

It handles only single-digit numbers. For multi-digit, I'd be inclined to have a look at takewhile and/or dropwhile, both in itertools (Python 2.7 and 3.x only.)


from string import maketrans

class redux:

    def __init__(self):
       intab = '+-'
       outtab = '  ' # two spaces
       self.trantab = maketrans(intab, outtab)

    
    def reduce_plusminus(self, s):
        list_form = [r[int(r[0]) + 1:] if r[0].isdigit() else r
                    for r
                    in s.translate(self.trantab).split()]
        return ''.join(list_form)

if __name__ == "__main__":
    p = redux()
    print p.reduce_plusminus(".+3ACG.+5CAACG.+3ACG.+3ACG")
    print p.reduce_plusminus("tA.-2AG.-2AG,-2ag")

    for n in range(100000): p.reduce_plusminus(".+3ACG.+5CAACG.+3ACG.+3ACG")

On Saturday, 5 January 2013 19:35:26 UTC+11, Sia  wrote:
> I have strings such as:
> 
> 
> 
> tA.-2AG.-2AG,-2ag
> 
> or
> 
> .+3ACG.+5CAACG.+3ACG.+3ACG
> 
> 
> 
> The plus and minus signs are always followed by a number (say, i). I want python to find each single plus or minus, remove the sign, the number after it and remove i characters after that. So the two strings above become:
> 
> 
> 
> tA..,
> 
> and
> 
> ...
> 
> 
> 
> How can I do that?
> 
> Thanks.