R/ochiais_index.R

In wilsontom/modelmisc: Miscellaneous tools for modelling

#' Ochiais Index
#'
#' Calculate  Ochiais Index between feature vectors
#'
#' @param x a character vector
#' @param y a character vector
#' @return a numeric value for Ochiais Index
#'
#' @export

ochiais_index <- function(x, y)
{
  if (!is.character(x)) {
    stop("x input must be a character")
  }
  if (!is.character(y)) {
    stop("y input must be a character")
  }
  x <- as.vector(na.omit(x))
  y <- as.vector(na.omit(y))

  oi.in <- length(intersect(x, y))
  oi.den <- sqrt(length(x) * length(y))
  oi <-  round(oi.in / oi.den, digits = 2)

  if (oi  > 1 | oi < 0) {
    stop("Ochiai's index is not between 0 and 1", call. = FALSE)
  }
  return(oi)
}