如何在ggplot2中翻转geom_curve（箭头）？

Question

我似乎无法使箭头变成凹形。angle我对其中的论点进行了多次调整geom_curve

可重现的例子

library(ggplot2)
library(dplyr)
set.seed(123)
data.frame(x = runif(200)* 1000, y = runif(200)* 1000) %>% 
  ggplot(aes(x, y)) +
  geom_point() + 
  geom_curve(
  aes(x = 200, y = 300, xend = 500, yend = 400),
  arrow = arrow(length = unit(0.03, "npc"), type="closed"), colour = "#EC7014", size = 1.2, angle = 90)

上面的箭头是凸的 - 目标是使箭头呈彩虹形状（凹）。我已经改变了angle起点/终点，但所有生成的箭头仍然是凸形的

实际例子

这里的箭头指向条形的粉红色部分 - 底部的箭头看起来不错，但如果可以将顶部的箭头做成凹面，看起来会更好

Answer 1

我想你想要curvature参数。正值具有逆时针卷曲，负值具有顺时针卷曲。这是一个代表：

library(ggplot2)

ggplot() + 
  geom_text(aes(x = -5, y = 5, label = "Some text"), size = 10, hjust = 0) +
  geom_rect(aes(xmin = 0, xmax = 5, ymin = 2.5, ymax = 7.5)) +
  geom_curve(aes(x = -2.5, y = 5.5, xend = -1.25, yend = 6),
             arrow = arrow(length = unit(0.03, "npc"), type="closed"), 
             colour = "#EC7014", size = 1.2, curvature = -0.3, angle = 90) +
  geom_curve(aes(x = -2.5, y = 4.5, xend = -1.25, yend = 4),
             arrow = arrow(length = unit(0.03, "npc"), type="closed"), 
             colour = "#EC7014", size = 1.2, curvature = 0.3, angle = 90)

^{由reprex 包(v0.3.0)于 2020-05-09 创建}