R/multi_plot.R

In mike-decarlo/augmentR: Additional Utility and Calculatory Functions

#' Plotting of multiple objects in a single window
#' The \code{multi_plot} function is meant to make plotting of multiple plot
#'   objects easier and more straightforward. Adapted from Winston Chang's
#'   "Cookbook for R".
#' @param plotlist A vector list of plot objects, e.g.
#'   c(plot1, plot2, ..., plot_n).
#' @param cols Number of columns in layout.
#' @param layout A matrix specifying the layout. If present, 'cols' is ignored.
#' @param ... further arguments (plot names) passed to or from other methods.
#' @keywords plot multi
#' @importFrom grid grid.newpage grid.layout viewport pushViewport
#' @export
multi_plot <- function(..., plotlist = NULL, cols = 1, layout = NULL) {
  # Make a list from the ... arguments and plotlist
  plots <- c(list(...), plotlist)
  num_plots <-  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(num_plots / cols)),
                     ncol = cols, nrow = ceiling(num_plots / cols))
  }
  if (num_plots == 1) {
    print(plots[[1]])
  } else {
    # Set up the page
    grid::grid.newpage()
    grid::pushViewport(grid::viewport(layout = grid::grid.layout(nrow(layout)
      , ncol(layout))))
    # Make each plot, in the correct location
    for (i in 1:num_plots) {
      # 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 = grid::viewport(layout.pos.row = matchidx$row
        , layout.pos.col = matchidx$col))
    }
  }
}