R/latticeCombineLayer.R

In Orcs: Omnidirectional R Code Snippets

#' Combine Multiple Lattice Plots Layerwise
#' 
#' @description
#' This function combines multiple **lattice** plot objects drawing each as a 
#' layer on top of the previous plots. Note that the global plot settings (e.g. 
#' 'xlim', 'ylim', ...) are taken from the first object. This is particularly 
#' useful when looping over large amounts of data using [lapply()] (see 
#' Examples).
#' 
#' @param trellis.list A `list` containing **lattice** plot objects.
#' @param ... Additional arguments passed to [latticeExtra::as.layer()].
#' 
#' @return
#' A single **lattice** plot object.
#' 
#' @author
#' Tim Appelhans
#' 
#' @seealso
#' [latticeExtra::as.layer()].
#' 
#' @examples
#' library(latticeExtra)
#' dat <- list(1:10,
#'             10:1,
#'             3:7,
#'             7:3)
#' 
#' plist <- lapply(seq(dat), function(i) {
#'  tmp <- xyplot(dat[[i]] ~ seq(dat[[i]]),
#'                type = "l", col = i)
#' })
#' 
#' p <- latticeCombineLayer(plist)
#' 
#' print(p)
#' 
#' @export
latticeCombineLayer <- function(trellis.list, ...) {
  
  outLayer <- function(x, y, ...) {
    x + latticeExtra::as.layer(y, ...)
  }
  
  out <- Reduce(outLayer, trellis.list, ...)
  return(out)
}