Use Regex to replace uppercase abbreviations with same letters but adding punctuation and space

user_11957996 0
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Suppose I have a sentence such as

   string = 'USA and EU are not hosting the SWCP'

Desired output - add a . and a space after each letter

'U. S. A. and E. U. are not hosting the S. W. C. P.'

I was thinking of using re.sub() but couldn't really figure out how to express the replacement and use the letters previously found by the regex.

reg = r'[A-Z]{2,4}'
string = re.sub(reg, ???, string)
python regex
2 Answers

You can replace matches of the following regular expression with ". ".

r'(?<=[A-Z])(?=[A-Z])|(?<=[A-Z]{2}) ?'

Start your engine! <¯\(ツ)/¯> Python code

(?<=[A-Z])     : use a positive lookbehind to assert previous character
                 is a capital letter
(?=[A-Z])      : use a positive lookahead to assert next character
                 is a capital letter
|              : or
(?<=[A-Z]{2})  : use a positive lookbehind to assert 2 previous
                 characters are capital letters
[ ]?           : optionally match a space

I've represented a space in the last line above as a character class containing a space for clarity. The character class is not needed.

Note that both components of the alternation match a location that is between consecutive characters.

The optional space ? is added after (?<=[A-Z]{2}) so that if a match is made after 'C' in 'ABC hi' the regex will match the space, thereby avoiding the introduction of an extra space when the replacement is made.

user_2569700

Using str.isupper() and str.isalpha():

s = 'USA and EU are not hosting the SWCP'
x = ''

for char in s:
    if char.isupper() and char.isalpha():
        x += char + '.'
    else:
        x += char
        
print(x)

one-liner:

print("".join(x + "." if x.isalpha() and x.isupper() else x for x in s))

OUTPUT:

U.S.A. and E.U. are not hosting the S.W.C.P.
user_51734260
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