R/xyrange.R

In plottools: Tools for plotting with style

#' @title Report x- and y-range, generic function
# @name rangexy (generic method)
#' @rdname rangexy
#' 
#' @description \code{xyrange} returns a list with elements \code{x} and \code{y}, 
#' vectors containing the minimum and maximum of \eqn{x}- and \eqn{y}-values the 
#' argument(s). This function serves to determine a plot region.
#' 
#'@param x,y numeric vectors of x- and y- coordinates, or alternatively a single 
#'argument \code{x}.
#'@param ... arguments passed to class methods, ignored in default method
#'  \code{rangexy.default}
#'@param finite logical, indicating if all non-finite elements should be omitted.
#'@export
#'@details 
#' The default method passes the arguments \code{x} and \code{y} to
#' function \code{\link{xy.coords}}. Therefore, reasonable results can also be 
#' expected when e.g. \code{y} is \code{NULL} and \code{x} is a list or data frame 
#' with components \code{x} and \code{y}.
#'  
#' If finite is \code{TRUE}, the minimum and maximum of all finite values is 
#' computed, and \code{NA} and \code{NaN} values are ignored.
#'@return A list with elements \code{x} and \code{y}.
#'@author Ute Hahn,  \email{ute@@imf.au.dk}
      
#' @seealso \code{\link{xy.coords}} for details on possible values of \code{x} when
#' \code{y} is \code{NULL}
#' @examples
#' df <- data.frame(x=1:4, y=(1:4)^2)
#' rangexy(df)
#' rangexy(1:4, 5:8)

rangexy <- function(...) UseMethod("rangexy")

#' @rdname rangexy
#' @method rangexy default
#' @S3method rangexy default
#' 
 
rangexy.default <- function (x, y=NULL, finite = TRUE, ...) {
  xy <- xy.coords(x, y)
  list(x = range(xy$x, finite = finite),
       y = range(xy$y, finite = finite))
}