在ggplot2中改变嵌套facet的美学

Question

我想使用嵌套面板,ggplot2但两个面板的名称必须位于绘图的两侧.这是一个可重复的例子:

library(ggplot2)
library(data.table)

# data for reproducible example
dt <- data.table(
  value = c("East", "West","East", "West", "NY", "LA","NY", "LA"),
  year = c(2008, 2008, 2013, 2013, 2008, 2008, 2013, 2013),
  index = c(12, 10, 18, 15, 10, 8, 12 , 14),
  var = c("Region","Region","Region","Region", "Metro","Metro","Metro","Metro"))

# change order or plot facets
dt[, var := factor(var, levels=c( "Region", "Metro"))]

# plot
ggplot(data=dt) +
  geom_point( aes(x=index, y= factor(year), color=index)) +
  facet_grid(value + var ~., scales = "free_y", space="free") 

请注意,在此示例中,我使用列value+ var来创建构面,但两个面板的标题一起绘制.

预期产出:我想要实现的目标是:

Answer 1

一个可能的解决方案,使用labeller = label_bquote(rows = .(var1))两个调用geom_text和一些进一步的自定义:

ggplot(dt, aes(x = index, y = factor(year), color = index)) +
  geom_point() +
  geom_text(aes(x = 6, y = 1.5, label = value), color = 'black', hjust = 0) +
  geom_text(aes(x = 7, label = year), color = 'black') +
  geom_segment(aes(x = 7.5, xend = 7.5, y = 0.7, yend = 2.3), color = 'black') +
  geom_segment(aes(x = 7.45, xend = 7.5, y = 1, yend = 1), color = 'black') +
  geom_segment(aes(x = 7.45, xend = 7.5, y = 2, yend = 2), color = 'black') +
  scale_x_continuous(breaks = seq(8,18,2)) +
  facet_grid(value + var1 ~., scales = "free_y", space="free", labeller = label_bquote(rows = .(var1))) +
  theme_minimal() +
  theme(axis.title = element_blank(),
        axis.text.y = element_blank(),
        strip.background = element_rect(color = 'darkgrey', fill = 'lightgrey'),
        panel.grid.major.y = element_blank(),
        panel.grid.minor = element_blank())

这使:

注意:我使用的是var1代替,var因为后者也是函数名.

另一种可能性是利用gridExtra包装来创建附加标签,并将它们放在y轴标签的前面grid.arrange:

# create the main plot
mainplot <- ggplot(dt, aes(x = index, y = factor(year), color = index)) +
  geom_point(size = 2) +
  scale_x_continuous(breaks = seq(8,18,2)) +
  facet_grid(value + var1 ~., scales = "free_y", space="free", labeller = label_bquote(rows = .(var1))) +
  theme_minimal() +
  theme(axis.title = element_blank(),
        strip.background = element_rect(color = 'darkgrey', fill = 'lightgrey'))

# create a 2nd plot with everything besides the labels set to blank or NA
lbls <- ggplot(dt, aes(x = 0, y = factor(year))) +
  geom_point(color = NA) +
  geom_text(aes(x = 0, y = 1.5, label = value), color = 'black') +
  scale_x_continuous(limits = c(0,0), breaks = 0) +
  facet_grid(value + var1 ~.) +
  theme_minimal() +
  theme(axis.title = element_blank(),
        axis.text.x = element_text(color = NA),
        axis.text.y = element_blank(),
        strip.background = element_blank(),
        strip.text = element_blank(),
        panel.grid = element_blank(),
        legend.position = 'none')

# plot with 'grid.arrange' and give the 'lbls'-plot a small width
library(gridExtra)
grid.arrange(lbls, mainplot, ncol = 2, widths = c(1,9))

这使: