Python Replace Single Quotes Except Apostrophes

Question

I am performing the following operations on lists of words. I read lines in from a Project Gutenberg text file, split each line on spaces, perform general punctuation substituti

Answer 1

I think this can benefit from lookahead or lookbehind references. The python reference is https://docs.python.org/3/library/re.html, and one generic regex site I often reference is https://www.regular-expressions.info/lookaround.html.

Your data:

words = ["don't",
         "'George",
         "ma'am",
         "end.'",
         "didn't.'",
         "'Won't",]

And now I'll define a tuple with regular expressions and their replacements.

In [230]: apo = (
    (re.compile("(?<=[A-Za-z])'(?=[A-Za-z])"), "",),
    (re.compile("(?",),
    (re.compile("(?<=[.A-Za-z])'(?![A-Za-z])"), "", ),
    (re.compile("(?<=[A-Za-z])\\.(?![A-Za-z])"), "",),
)
     ...:      ...:      ...:      ...:      ...:      ...: 
In [231]: words = ["don't",
         "'George",
         "ma'am",
         "end.'",
         "didn't.'",
         "'Won't",]
     ...:      ...:      ...:      ...:      ...:      ...: 
In [232]: reduce(lambda w2,x: [ x[0].sub(x[1], w) for w in w2], apo, words)
Out[232]: 
['dont',
 'George',
 'maam',
 'end',
 'didnt',
 'Wont']

Here's what's going on with the regexes:

1. (?<=[A-Za-z]) is a lookbehind, meaning only match (but do not consume) if the preceding character is a letter.
2. (?=[A-Za-z]) is a lookahead (still no consume) if the following character is a letter.
3. (? is a negative lookbehind, meaning if there is a letter preceding it, then it will not match.
4. (?![A-Za-z]) is a negative lookahead.

Note that I added a . check within , and the order within apo matters, because you might be replacing . with ...

This was operating on single words, but should work with sentences as well.

In [233]: onelong = """
don't
'George
ma'am
end.'
didn't.'
'Won't
"""
     ...:      ...:      ...:      ...:      ...:      ...:      ...: 
In [235]: print(
    reduce(lambda sentence,x: x[0].sub(x[1], sentence), apo, onelong)
)

     ...:      ...: 
dont
George
maam
end
didnt
Wont

(The use of reduce is to facilitate applying a regex's .sub on the words/strings and then keep that output for the next regex's .sub, etc.)