-cowplot get_legend（）当ggplot传说位置不在默认位置

Question

cowplot

的传说，但是当我尝试使用

grid.draw()

包装中绘制the Legend时，它会产生一个空白。

grid

发现没有提取传说，因为

library(cowplot); library(patchwork); library(grid); library(tidyverse)

#Data to create legend
legend_data <- data.frame(
  julian = 299:366,
  PM25 = c(3.4,1.3,1.2,1.2,0.4,3.4,1.0,0.8,0.3,13.5,0.9,5.3,4.4,3.4,98.6,0.7,350.6,0.8,0.3,0.9,0.9,4.1,0.7,0.3,0.4,2.1,1.4,5.2,4.2,3.9,1.4,0.8,0.7,0.8,0.3,1.9,0.8,0.7,1.2,1.7,67.9,3.8,6.1,5.9,225.3,0.7,0.3,0.6,2.9,37.5,1.1,33.2,0.9,1.5,1.1,0.8,1.5,0.8,2.2,4.6,1.2,1.0,3.3,0.9,0.9,4.6,1.2,2.8),
  site_name = "community 1"
  )
legend_data$AQI <- case_when(
  legend_data$PM25 <= 9.0 ~ "1",
  legend_data$PM25 >= 9.1 & legend_data$PM25 <= 35.4 ~ "2",
  legend_data$PM25 >= 35.5 & legend_data$PM25 <= 55.4 ~ "3",
  legend_data$PM25 >= 55.5 & legend_data$PM25 <= 125.4 ~ "4",
  legend_data$PM25 >= 125.5 & legend_data$PM25 <= 225.4 ~ "5",
  legend_data$PM25 >= 225.5 ~ "6",
  TRUE ~ NA_character_
)

#Create plot
legendplot <- ggplot(legend_data, aes(x=julian, y=AQI, fill=AQI)) +
  geom_tile() +
  scale_fill_manual(
    values = c("green", "yellow", "orange", "red", "purple", "maroon"),
    labels = c("1" = "Good", "2"="Moderate", "3" = "Unhealthy for\nSensitive Groups", "4" = "Unhealthy", "5" = "Very Unhealthy", "6" = "Hazardous")
  ) +
  theme(legend.position = "bottom")
legendplot

#Extract legend
legend<-cowplot::get_legend(legendplot) 
grid.newpage()
grid.draw(legend)

被设置为

legend.position

。

Answer 1

"bottom"

而不是

legend.position = "bottom"

时获得传奇

将值更改为以下值之一，以匹配

cowplot::get_plot_component(legendplot,"guide-box-bottom")

中提供的位置，如果您不使用默认值

cowplot::get_legend(legendplot)

：

：

guide-box

当，

theme(legend.position="")

，

legend.position

当，

guide-box-right

，
1. legend.position="right"

   当，

   guide-box-left
，
2. legend.position="left"

   当，

   guide-box-bottom
，
3. legend.position="bottom"

   当
   

4. guide-box-top