Matching a sequence in a larger vector

Question

I\'d like to have a function which returns the initial indicies of matching subsequences of a vector. For example:

y <- c(\"a\",\"a\",\"a\",\"b\",\"c\")

         


        

Answer 1

Try rollapply in zoo:

library(zoo)
which(rollapply(y, 2, identical, c("a", "a")))
## [1] 1 2
which(rollapply(y, 2, identical, c("a", "b")))
## [1] 3