格式化多个geom_sf图例

Question

我正在ggplot中处理多个sf几何形状，并希望以点，线和正方形（对于多边形）的形式显示图例。但是，geom_sf图例结合了下面显示的我的几何特征（即结合线和点）：

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()

在下面显示的同一张图片上，我想要三个单独的图例，一个黄色的正方形，一个粉红色的点和一条紫色的线。只有当我绘制单个几何图形而不是三个图形的组合时，这种情况才会出现。

我查找了类似的主题，但是它们都没有涉及点几何，即https://github.com/tidyverse/ggplot2/issues/2460

有人会对此提供任何见识吗？

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

Answer 1

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

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() 

Answer 2

我知道如何分隔图例，因为您两次绘制颜色，所以它们现在才合并在一起。通过将形状映射到这些点并设置颜色，您可以解决此问题：

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

但是：点和线仍在所有三个图例中显示。我认为他们不应该！也许您可以解决github问题。