R ggplot2:添加箭头会弄乱图例条目

我想做一个两组的散点图，然后添加一个箭头。但我不想让箭头出现在图例条目中，也不想弄乱以前的图例条目

下面是我的例子：

library(tidyverse)

df <- tribble(
  ~country, ~series1, ~series2, 
  #--|--|----
  "USA", 8, 5,
  "USA", 9, 6, 
  "USA", 11, 7, 
  "USA", 10, 8,
  "USA", 11, 4,
  "USA", 14, 10,
  "USA", 16, 12,
  "USA", 12, 8,
  "USA", 12, 13,
  "USA", 13, 10,
  "USA", 11, 5,
  "FRA", 5, 6, 
  "FRA", 6, 8, 
  "FRA", 5, 7, 
  "FRA", 4, 8,
  "FRA", 9, 11,
  "FRA", 7, 9, 
  "FRA", 14, 11,
  "FRA", 7, 11, 
  "FRA", 6, 6,
  "FRA", 5, 7,
  "FRA", 4, 5
)

ggplot(df, aes(x = series1, y = series2, color = country)) +
  geom_point() +
  geom_segment(aes(x = 4, xend=6, y = 11, yend=8), 
               arrow = arrow(length = unit(0.5, "cm")))

库（tidyverse）
df只需将
show.legend=FALSE
添加到
geom_段
geom<代码>网格：：箭头

没有提到任何关于“翅膀”长度的内容。你必须深入研究代码