#R#The multiplot() Function

轉載自：http://www.peterhaschke.com/r/2013/04/24/MultiPlot.html

The multiplot() Function

Quite often I want to print multiple figures to a device. When faceting is not an option this can be quite tedious. In days past, I have used a code snippet relying on the “grid” package to this. That piece of code is/was quite unintuitive and cannot be remembered (i.e. one has to look it up frequently and then copy and paste). My good friend Jonathan eventually posted it to the internet (here:ggplot-snippet).

Most recently, this issue came up again, when a certain scholar Tyson alerted me to a more generalized version of this code. It also leverages the “grid” package, but is much more general. It even has a name: multiplot().

I shamelessly lifted the code from the R-Cookbook and uploaded it here for all eternity. Now instead of hunting down that elusive snippet, I shall just type: source("http://peterhaschke.com/Code/multiplot.R") … so yeah!

Below the code for the multiplot() function:

multiplot <- function(..., plotlist = NULL, file, cols = 1, layout = NULL) {
  require(grid)

  plots <- c(list(...), plotlist)

  numPlots = length(plots)

  if (is.null(layout)) {
    layout <- matrix(seq(1, cols * ceiling(numPlots/cols)),
                    ncol = cols, nrow = ceiling(numPlots/cols))
  }

  if (numPlots == 1) {
    print(plots[[1]])

  } else {
    grid.newpage()
    pushViewport(viewport(layout = grid.layout(nrow(layout), ncol(layout))))

    for (i in 1:numPlots) {
      matchidx <- as.data.frame(which(layout == i, arr.ind = TRUE))

      print(plots[[i]], vp = viewport(layout.pos.row = matchidx$row,
                                      layout.pos.col = matchidx$col))
    }
  }
}