62377018.R

myFun <- function(vec, find, replace) {
  if (length(find) != length(replace)) stop("incompatible find/replace")
  if (all(find %in% vec)) {
    pos <- which(vec == find[1])
    for (i in seq_along(pos)) {
      ind <- pos[i]:(pos[i]+length(find)-1)
      if (identical(vec[ind], find)) vec[ind] <- replace
    }
  } else {
    message("nothing changed")
  }
  vec
}

Note the difference with find_subvec (https://stackoverflow.com/q/62377018/1270695).

x1 <- c(1,2,3,4,1,0,1)
x2 <- c(1,2,3,4,1,0,1,0,1)
myFun(x1, c(1, 0, 1), c(1, 1, 1))
# [1] 1 2 3 4 1 1 1
myFun(x2, c(1, 0, 1), c(1, 1, 1))
# [1] 1 2 3 4 1 1 1 1 1
myFun(x2, c(1, 0, 1), c(1, 1, 4))
# [1] 1 2 3 4 1 1 4 0 1

find_subvec <- function(invec, subvec, replace) {
  sublen <- seq_along(subvec) - 1L
  if (length(subvec) > length(invec)) return(integer(0))
  ind <- which(
    sapply(seq_len(length(invec) - length(subvec) + 1L),
           function(i) all(subvec == invec[i + sublen]))
  )
  for (i in ind) invec[i + seq_along(subvec) - 1] <- replace
  invec
}

find_subvec(x2, c(1, 0, 1), c(1, 1, 4))
# [1] 1 2 3 4 1 1 1 1 4