CODEWITHSUNDEEP
javapythonregex
Horseshaq
Horseshaq

Reputation: 23

Regex replace conditional character

I need to remove any 'h' in a string if it comes after a vowel.

E.g.
    John -> Jon
    Baht -> Bat
    Hot -> Hot (no change)
    Rhythm -> Rhythm (no change)

Finding the words isnt a problem, but removing the 'h' is as I still need the original vowel. Can this be done in one regex?

Upvotes: 0

Views: 108

Answers (1)

buld0zzr
buld0zzr

Reputation: 962

The regex for matching h after a vowel would be a positive lookbehind one

(?<=a|e|y|u|o|a)h

And you can do

re.sub(r"([a-zA-Z]*?)(?<=a|e|y|u|o|a)h([a-zA-Z]*)",r"\1\2",s)

However, if you can have more than one h after a vowel in a string, you would need to do several iterations, since regex doesn't support dynamic matching groups

import re

s = "bahtbaht"
s1 = s

while True:
    s1 = re.sub(r"([a-zA-Z]*?)(?<=a|e|y|u|o|a)h([a-zA-Z]*)",r"\1\2",s)
    if len(s1) == len(s):
        break
    s = s1

print(s1)

In a more proper form, using function for repl

import re

def subit(m):
    match, = m.groups()
    return match

s = "bahtbaht"

print(re.sub(r"([a-zA-Z]*?)(?:(?<=a|e|y|u|o|a)h|$)",subit,s))

A much simplier answer, thanks to @tobias_k

re.sub(r"([aeiou])h", r"\1", s, flags = re.I)

Upvotes: 2

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