Replace nth occurrence of substring in string

Question

I want to replace the n\'th occurrence of a substring in a string.

There\'s got to be something equivalent to what I WANT to do which is

mystring.repl

Answer 1

My two cents

a='01ab12ab23ab34ab45ab56ab67ab78ab89ab90';print('The original string: ', a)
sTar = 'ab';print('Look for: ', sTar)
n = 4; print('At occurence #:', n)
sSub = '***';print('Substitute with: ', sSub)

t = 0
for i in range(n):
   t = a.find(sTar,t)
   print(i+1, 'x occurence at', t)
   if t != -1: t+=1

t-=1   #reset, get the correct location
yy = a[:t] + a[t:].replace(sTar, sSub, 1)
print('New string is:', yy)

Output

The original string:  01ab12ab23ab34ab45ab56ab67ab78ab89ab90
Look for:  ab
At occurence #: 4
Substitute with:  ***
1 x occurence at 2
2 x occurence at 6
3 x occurence at 10
4 x occurence at 14
New string is: 01ab12ab23ab34***45ab56ab67ab78ab89ab90