Overlapping count of substring in a string in Python

Question

I want to find all the counts (overlapping and non-overlapping) of a sub-string in a string. I found two answers one of which is using regex which is not my intention and t

Answer 1

def sliding(a, n):
    return (a[i:i+n] for i in xrange(len(a) - n + 1))

def substring_count(a, b):
    return sum(s == b for s in sliding(a, len(b)))

assert list(sliding('abcde', 3)) == ['abc', 'bcd', 'cde']    
assert substring_count('ababaa', 'aba') == 2