In Python, How to find the start and end indices of the matching string K in the original string S?

Question

Ex: S=aaadaa and K=aa

Here we can find string "aa" at 3 positions
So need to print those 3 positions start and end positions as output 0/p :(0, 1), (1, 2), (4, 5)

Answer 1

Here a version with a for loop, but regex would be the preferred solution.

# using for loop:
txt = 'aaadaaxxaaaaax._::axaaaa'
s = 'aaaa'
for pos, i in enumerate(range(len(txt)-len(s)+1)):
if txt[i:i+len(s)] == s:
print((pos, pos+len(s)-1),end=' ')

Answer 2

As Bilbo Baggins suggested, a cheeky lookahead will help with the overlapping matches!

import re

s=list(re.finditer(r'a(?=a)', 'aaadaa'))
for e in s:
print(e.start(), e.end())

Answer 3

Can you show us what you've got so far?

Answer 4

e.end() must be replaced with e.end()-1

and in the link I suggested you is written that, for overlapping substrings, lookahead is required

Answer 5

Thanks all.. Got it now🙂

Answer 6

I just tried with below logic :

S=list(re.finditer(r'aa', aaadaa))
for e in s:
print(e.start(), e.end())

Got O/p as :
0 2
4 6

But expected output as
0 1
1 2
4 5

Answer 7

and do not forget google 😉

https://stackoverflow.com/questions/4664850/how-to-find-all-occurrences-of-a-substring