R/plot.R

In XiaomoWu/utilr: R Helper Functions

#' @export
# Invert grob title
#
# ggplot contains many labels that are themselves complex grob;
# usually a text grob surrounded by margins.
# When moving the grobs from, say, the left to the right of a plot,
# make sure the margins and the justifications are swapped around.
# The function below does the swapping.
# Taken from the cowplot package:
# https://github.com/wilkelab/cowplot/blob/master/R/switch_axis.R
hinvert_title_grob <- function(grob) {
    # Swap the widths
    widths <- grob$widths
    grob$widths[1] <- widths[3]
    grob$widths[3] <- widths[1]
    grob$vp[[1]]$layout$widths[1] <- widths[3]
    grob$vp[[1]]$layout$widths[3] <- widths[1]
    # Fix the justification
    grob$children[[1]]$hjust <- 1 - grob$children[[1]]$hjust
    grob$children[[1]]$vjust <- 1 - grob$children[[1]]$vjust
    grob$children[[1]]$x <- unit(1, "npc") - grob$children[[1]]$x
    grob
}


#' @export
# 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.
#
# 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.
#
multiplot <- function(..., plotlist = NULL, file, 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))
        }
    }
}