string substitution using regex

Question

I have this string in python

a = "haha" 
result = "hh"

What i would like to achieve is using regex to replace all occurrences of "aha" to "h" and all "oho" to "h" and all "ehe" to "h"

"h" is just an example. Basically, i would like to retain the centre character. In other words, if its 'eae' i would like it to be changed to 'a'

My regex would be this

"aha|oho|ehe"

I thought of doing this

import re
reg = re.compile('aha|oho|ehe')

However, i am stuck on how to achieve this kind of substitution without using loops to iterate through all the possible combinations?

Answer 1

You can use re.sub :

import re

print re.sub('aha|oho|ehe', 'h', 'haha')  # hh
print re.sub('aha|oho|ehe', 'h', 'hoho')  # hh
print re.sub('aha|oho|ehe', 'h', 'hehe')  # hh
print re.sub('aha|oho|ehe', 'h', 'hehehahoho')  # hhhahh

Answer 2

那么re.sub(r'[aeo]h[aeo]','h',a)呢？