2行ggplot2图例

Question

我无法找到将ggplot2图例放在2行的解决方案。

示例

library(ggplot2)
theme_set(theme_bw())
data("midwest", package = "ggplot2")

ggplot(midwest, aes(x=area, y=poptotal)) + 
  geom_point(aes(col=state, size=popdensity)) + 
  geom_smooth(method="loess", se=F) + 
  xlim(c(0, 0.1)) + 
  ylim(c(0, 500000)) + 
  labs(y="Population", 
       x="Area", 
       title="") +
  theme(legend.position = "top")

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在上面的图像中，我希望在上面(第一行)有popdensity 注释，在第二行中有 state 注释。

Answer 1

我想你是在找theme(legend.box = "vertical")和guide_legend(order = ...)

library(ggplot2)

data("midwest", package = "ggplot2")

ggplot(midwest, aes(x=area, y=poptotal)) + 
  geom_point(aes(col=state, size=popdensity)) + 
  geom_smooth(method="loess", se=F) + 
  xlim(c(0, 0.1)) + 
  ylim(c(0, 500000)) + 
  labs(y="Population", 
       x="Area", 
       title="") +
  theme_bw() +
  theme(legend.position = "top", 
        legend.box = "vertical") +
  guides(size = guide_legend(order = 1), 
         colour = guide_legend(order = 2))

​

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