R/image_scale.R

In ERottler/meltimr: Shiny App to investigate GRDC runoff data with regard to changes in runoff timing

#'Color scale for image plot.
#'
#' Plot color scale of image plot.
#'
#' @param z Input data matrix. Results of moving average analysis.
#' @param zlim Maximum and minimum values.
#' @param col Vector of colors for z-value.
#' @param breaks Color breaks in z-range.
#' @param horiz Orientation of image scale
#' @param ylim ...
#' @param xlim ...
#' @return Scale for image plot.
#' @export
#'
image_scale <- function(z, zlim, col, breaks, horiz=TRUE, ylim=NULL, xlim=NULL,...){
  if(!missing(breaks)){
    if(length(breaks) != (length(col)+1)){stop("must have one more break than colour")}
  }
  if(missing(breaks) & !missing(zlim)){
    breaks <- seq(zlim[1], zlim[2], length.out=(length(col)+1))
  }
  if(missing(breaks) & missing(zlim)){
    zlim <- range(z, na.rm=TRUE)
    zlim[2] <- zlim[2]+c(zlim[2]-zlim[1])*(1E-3)#adds a bit to the range in both directions
    zlim[1] <- zlim[1]-c(zlim[2]-zlim[1])*(1E-3)
    breaks <- seq(zlim[1], zlim[2], length.out=(length(col)+1))
  }
  poly <- vector(mode="list", length(col))
  for(i in seq(poly)){
    poly[[i]] <- c(breaks[i], breaks[i+1], breaks[i+1], breaks[i])
  }
  xaxt <- ifelse(horiz, "s", "n")
  yaxt <- ifelse(horiz, "n", "s")
  if(horiz){YLIM<-c(0,1); XLIM<-range(breaks)}
  if(!horiz){YLIM<-range(breaks); XLIM<-c(0,1)}
  if(missing(xlim)) xlim=XLIM
  if(missing(ylim)) ylim=YLIM
  graphics::plot(1,1,t="n",ylim=ylim, xlim=xlim, xaxt=xaxt, yaxt=yaxt, xaxs="i", yaxs="i", ...)
  for(i in seq(poly)){
    if(horiz){
      graphics::polygon(poly[[i]], c(0,0,1,1), col=col[i], border=NA)
    }
    if(!horiz){
      graphics::polygon(c(0,0,1,1), poly[[i]], col=col[i], border=NA)
    }
  }
}