如何在 ggplot2 中调整我的箭头方向？

Question

我正在创建一个ggplot图表，我希望在两点之间有一些箭头。 使用geom_line(arrow = arrow())可以轻松完成主要任务，但正如您所见，对于某些观察（德国、法国），箭头并不表示“Previo”到“Actual”的正确方向。 这是我的代码：

Countries = c("Eurozone","Eurozone","France","France","Germany","Germany","Japan","Japan","United.Kingdom","United.Kingdom","United.States","United.States")
PMI = c(62.5,63.3,59.3,59.2,66.6,66.4,52.7,53.3,58.9,60.7,59.1,60.6)
Delta1M = c(4.6,0.8,3.2,-0.1,5.9,-0.2,1.3,0.6,3.8,1.8,0.5,1.5)
Mes = c("Previo","Actual","Previo","Actual","Previo","Actual","Previo","Actual","Previo","Actual","Previo","Actual")

t1 <- data.frame(Countries,PMI,Delta1M,Mes)
t1$Mes <- factor(t1$Mes, levels = c("Previo","Actual"))

t1 %>% arrange(Countries) %>% 
  group_by(Countries) %>% 
  ggplot(aes(x = PMI, y = Delta1M, group = Countries))+
  geom_point(aes(color = Countries, alpha = Mes), size = 3)+
  geom_line(arrow = arrow(length=unit(0.15,"cm"), ends="last", type = "closed"))+
  geom_hline(yintercept = 0)+
  geom_vline(xintercept = 50)+
  theme_minimal()+
  scale_alpha_manual(values = c(0.3,1))

Answer 1

按 Mes 排序并使用geom_path似乎可以工作，方法是按排序数据的顺序绘制线条，而不是基于 x 级数。

t1 %>% arrange(Countries, Mes) %>% 
  ggplot(aes(x = PMI, y = Delta1M, group = Countries))+
  geom_point(aes(color = Countries, alpha = Mes), size = 3)+
  geom_path(arrow = arrow(length=unit(0.15,"cm"), ends="last", type = "closed"))+
  geom_hline(yintercept = 0)+
  geom_vline(xintercept = 50)+
  theme_minimal()+
  scale_alpha_manual(values = c(0.3,1))