R/multiplot.R

In ShanEllis/methylarking: Analyzing RRBS Data

#' Multiplot function
#'
#' @param cols Number of columns \code{cols}
#' @param plotlist Null \code{plotlist}
#' @param file FILE \code{file}
#' @param layout A matrix specifying the layout. If present, 'cols' is ignored.
#'
#' @return allow ggplot to multipanel plot
#' 
#' @keywords multiplot, DMR
#'
#' @export
#' 
#' @examples
#' multiplot(p1,p2,p3, cols=3)

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