R/abline.R

In USGS-R/gsplot: Geological Survey Plotting

#' gsplot abline
#'
#' Creates straight lines on the existing gsplot object. See \code{\link[graphics]{abline}} for more details. 
#' 
#' @param object gsplot object
#' @param \dots Further graphical parameters may also be supplied as arguments. See 'Details'.
#' 
#' @details Additional graphical parameter inputs:
#' \itemize{
#'  \item{\code{a, b}} {slope, y-intercept}
#'  \item{\code{h}} {the y-value specifying a horizontal line}
#'  \item{\code{v}} {the x-value specifying a vertical line}
#'  \item{\code{col, lty, lwd}} {parameters describing the color, type, and width of the line, respectively}
#'  \item{\code{legend.name}} {name that appears in the legend, see \code{\link{legend}} for more legend parameters}
#' } 
#'  
#'
#' @export
#' @seealso \code{\link[graphics]{abline}}
#' @examples
#' gs <- gsplot()
#' gsNew <- points(gs, y=1, x=2, col="blue", pch=18, legend.name="Points")
#' gsNew <- lines(gsNew, c(3,4,3), c(2,4,6), legend.name="Lines")
#' gsNew <- abline(gsNew, b=1, a=0, legend.name="1:1")
#' gsNew <- legend(gsNew, location="topleft",title="Awesome!")
#' gsNew
abline <- function(object, ...) {
  override("graphics", "abline", object, ...)
}


abline.gsplot <- function(object, ..., legend.name=NULL, side=c(1,2)){
  fun.name <- 'abline'
  object <- gather_function_info(object, fun.name, ..., legend.name=legend.name, side=side)

  object <- modify_side(object, args = list(...), side=side)
  
  return(object)
}