R/multiplot.R

# Multiple plot function
#
# ggplot objects can be passed in ..., or to plotlist (as a list of ggplot objects)
# - cols:   Number of columns in layout
# - layout: A matrix specifying the layout. If present, 'cols' is ignored.
#
#' plots multiple ggplot plots in a grid
#'
#' Copied directly from: http://www.cookbook-r.com/Graphs/Multiple_graphs_on_one_page_(ggplot2)/
#'
#' @param ... list of ggplot2 objects to plot
#' @param plotlist A list of plots to add to
#' @param cols the number of columns in the resulting plot grid
#' @param layout custom layout design If the layout is something like
#' matrix(c(1,2,3,3), nrow=2, byrow=TRUE), then plot 1 will go in the upper
#' left, 2 will go in the upper right, and 3 will go all the way across the
#' bottom.
#' @return plots the ggplots
#' @export
#
multiplot <- function(..., plotlist=NULL, cols = 1, layout=NULL) {
  library(grid)

  # Make a list from the ... arguments and plotlist
  plots <- c(list(...), plotlist)

  numPlots = length(plots)

  # If layout is NULL, then use 'cols' to determine layout
  if (is.null(layout)) {
    # Make the panel
    # ncol: Number of columns of plots
    # nrow: Number of rows needed, calculated from # of cols
    layout <- matrix(seq(1, cols * ceiling(numPlots/cols)),
                     ncol = cols, nrow = ceiling(numPlots/cols))
  }

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

  } else {
    # Set up the page
    grid.newpage()
    pushViewport(viewport(layout = grid.layout(nrow(layout), ncol(layout))))

    # Make each plot, in the correct location
    for (i in 1:numPlots) {
      # Get the i,j matrix positions of the regions that contain this subplot
      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))
    }
  }
}
mattmills49/helpers documentation built on May 21, 2019, 1:25 p.m.