ggplot2画图

ggplot2 画图的辅助函数

# dual y-axis plot function
#
dual_axis_plot=function(p1,p2){
  require(grid)
  require(gtable)
  grid.newpage()
  ## convert plots to gtable objects
  g1 <- ggplot_gtable(ggplot_build(p1))  
  g2 <- ggplot_gtable(ggplot_build(p2))  
  # overlap the panel of 2nd plot on that of 1st plot  
  pp <- c(subset(g1$layout, name == "panel", se = t:r))  
  g <- gtable_add_grob(g1, g2$grobs[[which(g2$layout$name == "panel")]], pp$t,  
                        pp$l, pp$b, pp$l)  
  
  # axis tweaks  
  ia <- which(g2$layout$name == "axis-l")
  ga <- g2$grobs[[ia]]
  ax <- ga$children[[2]]
  ax$widths <- rev(ax$widths)
  ax$grobs <- rev(ax$grobs)
  ax$grobs[[1]]$x <- ax$grobs[[1]]$x - unit(1, "npc") + unit(0.15, "cm")
  g <- gtable_add_cols(g, g2$widths[g2$layout[ia, ]$l], length(g$widths) +0.1)
  g <- gtable_add_grob(g, ax, pp$t, length(g$widths) +0.1, pp$b)
  ia <- which(g2$layout$name == "ylab")
  ga <- g2$grobs[[ia]]
  ga$rot <- 270
  g =  gtable_add_cols(g, g2$widths[g2$layout[ia, ]$l], length(g$widths) +0.1)
  g = gtable_add_grob(g, ga, pp$t, length(g$widths) +0.1 , pp$b)
  grid.draw(g)
}


# 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))
  }
  #print(layout)
  
 if (numPlots==1) {
    print(plots[[1]])

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

    #print(plots)  
    # 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))
    }
  }
}