calc_streak.R

#' Calculate hit streaks
#'
#' @param x A character vector of hits (`"H"`) and misses (`"M"`).
#' @return A data frame with one column, `length`, containing the length of 
#' each hit streak.
#' @examples
#' data(kobe_basket)
#' calc_streak(kobe_basket$shot)
#'
#' @export

calc_streak <- function(x) {
  if (!is.atomic(x))
    x <- x[, 1]
  if (any(!x %in% c("H","M")))
    stop('Input should only contain hits ("H") and misses ("M")')

    y <- rep(0, length(x))
    y[x == "H"] <- 1
    y <- c(0, y, 0)
    wz <- which(y == 0)
    streak <- diff(wz) - 1

    return(data.frame(length = streak))
}