Count Overlapping Occurrences of Substring - Python Examples
Python - Find number of overlapping occurrences of a substring
There could be scenarios where the occurrences of a substring in a string could be overlapping. An example would be, the string abababa
has overlapping occurrences of substring aba
.
In this tutorial, we shall learn how to find the number of these overlapping occurrences of a substring, in a given string.
Steps to find the number of overlapping occurrences
To get the total number of occurrences of a substring in a string, where the occurrences could be overlapping, follow these steps.
- Traverse through the string using for loop and
range(len(string))
. - Find the
index
of the first occurrence of thesubstring
usingString.find(substring, start)
. - If index is non-negative, update the
start
with the result ofindex
obtained in above step. Also increment the counter and update the looping variable of for loop in step 1 to index+1. If index is negative, break for loop. - Counter would have the number of occurrences of a substring in the string.
Examples
1. Find number of overlapping occurrences of a search string in given string
In the following program, we have taken a string, and then a substring. We shall find the overlapping occurrences of substring in the string.
Python Program
string = 'abcdefghghghghghgh.'
substring = 'ghg'
count = 0
start = 0
if(len(string)>0 and len(string)<201):
for i in range(len(string)):
i = string.find(substring, start)
if(i>0):
start = i+1
count += 1
else:
break
print(count)
Output
5
Summary
In this tutorial of Python Examples, we learned how to find the occurrences of a substring in a string, where the occurrences could be overlapping.