split string into multi-character "letters"

Alexander Kapps alex.kapps at web.de
Wed Aug 25 22:26:53 CEST 2010

Jed wrote:
> Hi, I'm seeking help with a fairly simple string processing task.
> I've simplified what I'm actually doing into a hypothetical
> equivalent.
> Suppose I want to take a word in Spanish, and divide it into
> individual letters.  The problem is that there are a few 2-character
> combinations that are considered single letters in Spanish - for
> example 'ch', 'll', 'rr'.
> Suppose I have:
> alphabet = ['a','b','c','ch','d','u','r','rr','o'] #this would include
> the whole alphabet but I shortened it here
> theword = 'churro'
> I would like to split the string 'churro' into a list containing:
> 'ch','u','rr','o'
> So at each letter I want to look ahead and see if it can be combined
> with the next letter to make a single 'letter' of the Spanish
> alphabet.  I think this could be done with a regular expression
> passing the list called "alphabet" to re.match() for example, but I'm
> not sure how to use the contents of a whole list as a search string in
> a regular expression, or if it's even possible.  My real application
> is a bit more complex than the Spanish alphabet so I'm looking for a
> fairly general solution.
> Thanks,
> Jed

I don't know the Spanish alphabet, and you didn't say in what way 
your real application is more complex, but maybe something like this 
could be a starter:

In [13]: import re

In [14]: theword = 'churro'

In [15]: two_chars=["ch", "rr"]

In [16]: re.findall('|'.join(two_chars)+"|[a-z]", theword)
Out[16]: ['ch', 'u', 'rr', 'o']

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