ggplot 分开的图例和情节 [英] ggplot separate legend and plot

问题描述

我正在使用 grid lpackage 来放置我用 ggplot2 制作的图表:

I am using the grid lpackage to place my graphs that I made with ggplot2:

library(ggplot2)
library(grid)

Layout <- grid.layout(nrow = 4, ncol = 4,
          widths = unit(1, "null"), 
          heights = unit(c(0.4, 0.8, 1.2, 1.2), c("null", "null", "null")))
grid.show.layout(Layout)

plot1 = ggplot(diamonds, aes(clarity, fill = color)) + 
            geom_bar() + 
            facet_wrap(~cut, nrow = 1)
print(plot1 + theme(legend.position = "none"), 
vp = viewport(layout.pos.row = 3, layout.pos.col = 1:4))

问题是我想把情节放在第三行 (3,1) - (3,4) 并将图例放在 (4,4) 位置.不幸的是，我真的找不到一种方法来创建一个图例变量.我在网上搜索，我得到的最接近的是使用较旧的+ opts(keep = "legend_box") 但这已被弃用.

The problem is that I want to put the plot on the third row (3,1) - (3,4) and put the legend at the (4,4) position. Unfortunately, I can't really find a way to create just a legend variable. I searched online and the closest that I got was using the older + opts(keep = "legend_box") but that has been deprecated.

较旧的解决方案.

推荐答案

您可以从 ggplot 的 grob 对象中获取图例.然后你可以使用 grid.arrange 函数来定位所有东西.

You can get the legend from the grob object of the ggplot. Then you could use the grid.arrange function to position everything.

library(gridExtra)
g_legend<-function(a.gplot){
    tmp <- ggplot_gtable(ggplot_build(a.gplot))
    leg <- which(sapply(tmp$grobs, function(x) x$name) == "guide-box")
    legend <- tmp$grobs[[leg]]
    legend
}

legend <- g_legend(plot1)

grid.arrange(legend, plot1+ theme(legend.position = 'none'), 
    ncol=2, nrow=1, widths=c(1/6,5/6))

网络上有很多使用 g_legend 函数的示例.

There are lots of examples on the web using the g_legend function.

HTH

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