根据渐变图上的经纬度范围改变点形状

Question

我有一个渐变贴图，代码如下：

library(ggplot2)
ggplot(data = world) +
  geom_sf() +
  coord_sf(xlim = c(125.8, 129.8), ylim = c(33.0, 38.95), expand = FALSE) + 
  geom_point(aes(Lon, Lat,color=meanrow),data=master,size=3) +  
  scale_color_gradient(low = "green", high="red") + 
  labs(title = "Mean Annual Precipitation from 2001-2020", x = "Longitude", y="Latitude", color="Annual Precipitation (mm)") + 
  #geom_text(aes(Lon, Lat),data=master,label=master$Ename,nudge_y = .1,size=2.8)+
  geom_hline(yintercept=37, linetype="dashed", color="red") +
  geom_segment(x=127,y=33, xend=127, yend=37, linetype="dashed", color="red")

看起来像这样：

现在我想做的是根据它们位于虚线的哪一侧来改变点的形状。这是否可以通过代码轻松完成，因为我预计我将不得不经常更改边界线的位置。

编辑：感谢@danlooo 的帮助，我能够做我想做的事，这就是现在的样子：

x=master$Lon
y=master$Lat
x_intercept <- 127
y_intercept <- 37

shape=case_when(
  y > y_intercept ~ "top",
  y < y_intercept & x < x_intercept ~ "lower left",
  TRUE ~ "other")
ggplot(data = world) +
  geom_sf() +
  coord_sf(xlim = c(125.8, 129.8), ylim = c(33.0, 38.95), expand = FALSE) + 
  geom_point(aes(x=Lon, y=Lat,color=meanrow,shape=shape),data=master,size=3) +  
  scale_color_gradient(low = "green", high="red") + 
  labs(title = "Mean Annual Precipitation from 2001-2020", x = "Longitude", y="Latitude", color="Annual Precipitation (mm)") + 
  #geom_text(aes(Lon, Lat),data=master,label=master$Ename,nudge_y = .1,size=2.8)+
  geom_hline(yintercept=37, linetype="dashed", color="red") +
  geom_segment(x=127,y=33, xend=127, yend=37, linetype="dashed", color="red")

updated map

Answer 1

您可以根据预定义的阈值计算新列中的形状，这也将用于绘制线条：

library(tidyverse)

y_intercept <- 1
x_intercept <- 5.5

iris %>%
  mutate(
    x = Sepal.Length,
    y = Petal.Width,
    shape = case_when(
      y > y_intercept & x > x_intercept ~ "top right",
      y > y_intercept & x < x_intercept ~ "top left",
      TRUE ~ "other"
    )
  ) %>%
  ggplot(aes(x, y)) +
  geom_point(aes(shape = shape), size = 5) +
  geom_vline(xintercept = x_intercept) +
  geom_hline(yintercept = y_intercept)

^{由 reprex package (v2.0.0)}

于 2022-05-04 创建

根据渐变图上的经纬度范围改变点形状

Change point shapes based on longitude and latitude range on gradient map

r

ggplot2