Count number of occurrences when string contains substring

Question

I have string like

'abbb'

I need to understand how many times I can find substring 'bb'.

grep('bb','abbb')

returns 1. Therefore, the answer is 2 (a-bb and ab-bb). How can I count number of occurrences the way I need?

Answer 1

You can make the pattern non-consuming with '(?=bb)', as in:

length(gregexpr('(?=bb)', x, perl=TRUE)[[1]])
[1] 2