R/which_paddock_row.R

In IhsanKhaliq/ascotraceR: Simulate the Spread of Ascochyta Blight in Chickpea

#' Returns the row numbers of an x y data.table
#'
#' @param paddock The template data.table you wish to know the row numbers of
#' @param query data.frame with column names 'x' and 'y' for which you want to
#'   know the row number of in the paddock data.table
#'
#' @return Vector of row numbers
#'
#' @examples
#' pdk <- CJ(x = 1:100,
#'           y = 1:100)
#' qry <- pdk[sample(1:nrow(pdk), 5), ]
#' which_paddock_row(paddock = pdk, query = qry)
#' @keywords internal
#' @noRd
which_paddock_row <- function(paddock, query){
  x <- y <- NULL

  rows1 <- apply(query, 1, function(qu){
      y_max <- paddock[, max(y)]
      x_max <- paddock[, max(x)]
      x_rows <- qu["x"]
      y_rows <- (qu["y"] * x_max) - x_max
      return(x_rows + y_rows)
    })

  return(unlist(rows1))
}