r - 格式化多个 geom_sf 图例

Question

我正在 ggplot 中处理多个 sf 几何图形，并希望以点、线和正方形(对于多边形)的形式显示图例。然而，geom_sf图例结合了我的几何特征(即结合线和点)如下所示:

library(ggplot2)
library(sf)

poly1 <- cbind(lon = c(5, 6, 7, 5), lat = c(52, 53, 51, 52))

poly <- st_sf(st_sfc(st_polygon(list(poly1))))
line <- st_sf(st_sfc(list(st_linestring(cbind(lon = c(5.5, 4.5), lat = c(53.5, 54.5))))))
point <- st_sf(st_sfc(st_point(cbind(lon = 5.5, lat = 52.7))))

ggplot() +
  geom_sf(data = poly, aes(fill = "A")) +
  geom_sf(data = point, aes(colour = "B"), show.legend = "point") +
  geom_sf(data = line, aes(colour = "C"), show.legend = "line") +
  scale_fill_manual(values = c("A" = "yellow")) +
  scale_colour_manual(values = c("B" = "pink", "C" = "purple")) +
  theme_minimal()

我想要三个独立的图例，一个黄色方块、一个粉红色点和下图所示的同一图像上的一条紫色线。只有当我绘制单个几何图形而不是三个的组合时才会出现这种情况。







我查找了类似的主题，但没有一个涉及点几何，即 https://github.com/tidyverse/ggplot2/issues/2460

有人会对此提供任何见解吗？

GitHub 问题:https://github.com/tidyverse/ggplot2/issues/2763

Answer 1

受到@Axeman 评论的启发，this issue和 this post ，使用override.aes解决了问题参数在 guide_legend() :

library(ggplot2)
library(sf)

poly1 <- cbind(lon = c(5, 6, 7, 5), lat = c(52, 53, 51, 52))

poly <- st_sf(st_sfc(st_polygon(list(poly1))))
line <- st_sf(st_sfc(list(st_linestring(cbind(lon = c(5.5, 4.5), lat = c(53.5, 54.5))))))
point <- st_sf(st_sfc(st_point(cbind(lon = 5.5, lat = 52.7))))

ggplot() +
  geom_sf(data = poly, aes(fill = "A")) +
  geom_sf(data = point, aes(colour = "B"), show.legend = "point") +
  geom_sf(data = line, aes(colour = "C"), show.legend = "line") +
  scale_fill_manual(values = c("A" = "yellow"), name = NULL,
                    guide = guide_legend(override.aes = list(linetype = "blank", shape = NA))) +
  scale_colour_manual(values = c("B" = "pink", "C" = "purple"), name = NULL,
                      guide = guide_legend(override.aes = list(linetype = c("blank", "solid"), 
                                                               shape = c(16, NA)))) +
  theme_minimal()