如何在ggplot分组图空白位置自定义图例标签

ggplot2绘制分组图后，想将自定义的图例标签放在空白位置如下图（红色和绿色线段和文字）下图基础代码如下

1. library(ggplot2)
   
2. 
   
3. f_labels <- data.frame(drv = c("4","f","r"), label = c("4wd","Front","Rear"), agl = c("slop:44.97", 44.84, 44.76))
   
4. 
   
5. p <- ggplot(mpg, aes(x = displ, y = hwy)) + geom_point() + facet_wrap (~ drv, nrow = 2)

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   theme(legend.position = c(0.85, 0.9))

theme(legend.position = c(0.85, 0.9))

红色和绿色线段，如果是图例，可以根据具体分组进行画图，自己就会出来。文字标签添加如下：

1. df.new <- f_labels %>%
   
2.   unite("labels", label, agl, sep = "\n", remove = T) %>%
   
3.   mutate(displ = 6, hwy = 40)
   
4. 
   
5. ggplot() +
   
6.   geom_point(data = mpg,
   
7.              mapping = aes(x = displ, y = hwy)) +
   
8.   facet_wrap (~ drv, nrow = 2) +
   
9.   geom_text(data = df.new,
   
10.             mapping = aes(x = displ, y = hwy,label = labels))

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