Python, remove all non-alphabet chars from string

I am writing a python MapReduce word count program. Problem is that there are many non-alphabet chars strewn about in the data, I have found this post Stripping everything but alphanumeric chars from a string in Python which shows a nice solution using regex, but I am not sure how to implement it

def mapfn(k, v):
    print v
    import re, string 
    pattern = re.compile('[W_]+')
    v = pattern.match(v)
    print v
    for w in v.split():
        yield w, 1

I’m afraid I am not sure how to use the library re or even regex for that matter. I am not sure how to apply the regex pattern to the incoming string (line of a book) v properly to retrieve the new line without any non-alphanumeric chars.

Suggestions?

Answer

Use re.sub

import re

regex = re.compile('[^a-zA-Z]')
#First parameter is the replacement, second parameter is your input string
regex.sub('', 'ab3d*E')
#Out: 'abdE'

Alternatively, if you only want to remove a certain set of characters (as an apostrophe might be okay in your input…)

regex = re.compile('[,.!?]') #etc.