R/percX.R

In inSileco/graphicsutils: Collection of graphics utilities

#' Values at a given percentage of the axis
#'
#' Returns the values of either x-axis or y-axis for a given percentage.
#'
#' @param percentage The percentage of the axis for which the values is 
#' returned.
#'
#' @details
#' This function intends to ease the positioning of additional marks on plot 
#' (such as annotation). Note that percentages refer to the entire plot window.
#'
#' @export
#'
#' @examples
#' plot0()
#' text(x = percX(90), y = percY(90), label = "cool")
#'
#' @describeIn percX Returns the values of x-axis for a given percentage.
percX <- function(percentage = 90) {
    stopifnot(percentage >= 0 & percentage <= 100)
    alg.x <- graphics::par()$usr[1L] + 0.01 * percentage * 
        (graphics::par()$usr[2L] - graphics::par()$usr[1L])
    alg.x
}


#' @describeIn percX Returns the values of y-axis for a given percentage.
#' @export
percY <- function(percentage = 90) {
    stopifnot(percentage >= 0 & percentage <= 100)
    alg.y <- graphics::par()$usr[3L] + 0.01 * percentage * 
        (graphics::par()$usr[4L] -graphics::par()$usr[3L])
    alg.y
}