如何在 ggplot(带有图例)中制作宽度一致的图? [英] How can I make consistent-width plots in ggplot (with legends)?

问题描述

我有几个不同的类别要绘制.这些是不同的类别，每个类别都有自己的一组标签，但在文档中组合在一起是有意义的.下面给出一些简单的堆积条形图示例:

I've got a few different categories that I want to plot. These are different categories, each with their own set of labels, but which makes sense to group together in the document. The following gives some simple stacked bar chart examples:

df <- data.frame(x=c("a", "b", "c"),
                 y=c("happy", "sad", "ambivalent about life"))
ggplot(df, aes(x=factor(0), fill=x)) + geom_bar()
ggplot(df, aes(x=factor(0), fill=y)) + geom_bar()

问题在于，对于不同的标签，图例具有不同的宽度，这意味着绘图具有不同的宽度，如果我制作表格或 subfigure 元素，会导致事情看起来有点傻.我该如何解决这个问题?

The problem is that with different labels, the legends have different widths, which means the plots have different widths, leading to things looking a bit goofy if I make a table or subfigure elements. How can I fix this?

有没有办法明确设置绘图或图例的宽度(绝对或相对)?

Is there a way to explicitly set the width (absolute or relative) of either the plot or the legend?

推荐答案

egg 包很容易

# install.packages("egg")

library(egg)

p1 <- ggplot(data.frame(x=c("a","b","c"),
                        y=c("happy","sad","ambivalent about life")),
             aes(x=factor(0),fill=x)) + 
      geom_bar()
p2 <- ggplot(data.frame(x=c("a","b","c"),
                        y=c("happy","sad","ambivalent about life")),
             aes(x=factor(0),fill=y)) + 
      geom_bar()

ggarrange(p1,p2, ncol = 1)

原版更新至 ggplot2 2.2.1

Original Udated to ggplot2 2.2.1

这是一个使用 gtable 包中的函数的解决方案，并专注于图例框的宽度.(可以找到更通用的解决方案 此处.)

Here's a solution that uses functions from the gtable package, and focuses on the widths of the legend boxes. (A more general solution can be found here.)

library(ggplot2)   
library(gtable)    
library(grid)
library(gridExtra) 

# Your plots
p1 <- ggplot(data.frame(x=c("a","b","c"),y=c("happy","sad","ambivalent about life")),aes(x=factor(0),fill=x)) + geom_bar()
p2 <- ggplot(data.frame(x=c("a","b","c"),y=c("happy","sad","ambivalent about life")),aes(x=factor(0),fill=y)) + geom_bar()

# Get the gtables
gA <- ggplotGrob(p1)
gB <- ggplotGrob(p2)

# Set the widths
gA$widths <- gB$widths

# Arrange the two charts.
# The legend boxes are centered
grid.newpage()
grid.arrange(gA, gB, nrow = 2)

如果另外，图例框需要左对齐，从此处 由@Julius 撰写

If in addition, the legend boxes need to be left justified, and borrowing some code from here written by @Julius

p1 <- ggplot(data.frame(x=c("a","b","c"),y=c("happy","sad","ambivalent about life")),aes(x=factor(0),fill=x)) + geom_bar()
p2 <- ggplot(data.frame(x=c("a","b","c"),y=c("happy","sad","ambivalent about life")),aes(x=factor(0),fill=y)) + geom_bar()

# Get the widths
gA <- ggplotGrob(p1)
gB <- ggplotGrob(p2)

# The parts that differs in width
leg1 <- convertX(sum(with(gA$grobs[[15]], grobs[[1]]$widths)), "mm")
leg2 <- convertX(sum(with(gB$grobs[[15]], grobs[[1]]$widths)), "mm")

# Set the widths
gA$widths <- gB$widths

# Add an empty column of "abs(diff(widths)) mm" width on the right of 
# legend box for gA (the smaller legend box)
gA$grobs[[15]] <- gtable_add_cols(gA$grobs[[15]], unit(abs(diff(c(leg1, leg2))), "mm"))

# Arrange the two charts
grid.newpage()
grid.arrange(gA, gB, nrow = 2)

替代方案gtable 包中有rbind 和cbind 函数，用于将grob 合并为一个grob.对于此处的图表，应使用 size = "max" 设置宽度，但 gtable 的 CRAN 版本会引发错误.

Alternative solutions There are rbind and cbind functions in the gtable package for combining grobs into one grob. For the charts here, the widths should be set using size = "max", but the CRAN version of gtable throws an error.

一个选项:很明显，第二个图中的图例更宽.因此，请使用 size = "last" 选项.

One option: It should be obvious that the legend in the second plot is wider. Therefore, use the size = "last" option.

# Get the grobs
gA <- ggplotGrob(p1)
gB <- ggplotGrob(p2)

# Combine the plots
g = rbind(gA, gB, size = "last")

# Draw it
grid.newpage()
grid.draw(g)

左对齐图例:

# Get the grobs
gA <- ggplotGrob(p1)
gB <- ggplotGrob(p2)

# The parts that differs in width
leg1 <- convertX(sum(with(gA$grobs[[15]], grobs[[1]]$widths)), "mm")
leg2 <- convertX(sum(with(gB$grobs[[15]], grobs[[1]]$widths)), "mm")

# Add an empty column of "abs(diff(widths)) mm" width on the right of 
# legend box for gA (the smaller legend box)
gA$grobs[[15]] <- gtable_add_cols(gA$grobs[[15]], unit(abs(diff(c(leg1, leg2))), "mm"))

# Combine the plots
g = rbind(gA, gB, size = "last")

# Draw it
grid.newpage()
grid.draw(g)

第二种选择是使用 Baptiste 的 gridExtra 包中的 rbind

A second option is to use rbind from Baptiste's gridExtra package

# Get the grobs
gA <- ggplotGrob(p1)
gB <- ggplotGrob(p2)

# Combine the plots
g = gridExtra::rbind.gtable(gA, gB, size = "max")

# Draw it
grid.newpage()
grid.draw(g)

左对齐图例:

# Get the grobs
gA <- ggplotGrob(p1)
gB <- ggplotGrob(p2)

# The parts that differs in width
leg1 <- convertX(sum(with(gA$grobs[[15]], grobs[[1]]$widths)), "mm")
leg2 <- convertX(sum(with(gB$grobs[[15]], grobs[[1]]$widths)), "mm")

# Add an empty column of "abs(diff(widths)) mm" width on the right of 
# legend box for gA (the smaller legend box)
gA$grobs[[15]] <- gtable_add_cols(gA$grobs[[15]], unit(abs(diff(c(leg1, leg2))), "mm"))

# Combine the plots
g = gridExtra::rbind.gtable(gA, gB, size = "max")

# Draw it
grid.newpage()
grid.draw(g)

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