多个geom_sf图例的格式化

Question

我正在处理多个sf几何图形，希望以点、线和正方形（用于多边形）的形式显示图例。然而，geom_sf图例将我的几何特征组合在一起（即组合线和点），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()

我希望在下面的图像上获得三个单独的图例，一个黄色正方形，一个粉色点和一条紫色线。当我绘制单独的几何图形时才会出现这种情况，而不是三者的组合。

我查阅了类似的主题，但没有涉及点几何，即https://github.com/tidyverse/ggplot2/issues/2460。

有人能提供任何见解吗？

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

- Jane

Answer 1

受 @Axeman 评论启发，解决了这个问题。详情请见 此问题 和 此帖子。使用 guide_legend() 中的 override.aes 参数即可解决问题。

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() 

- Jane

Answer 2

我知道如何分离图例，现在它们只会组合在一起是因为您将颜色映射两次。通过将形状映射到点并设置颜色，您可以避免这种情况:

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：在所有三个图例中仍然显示了点和线。我认为它们不应该出现！也许你可以提交一个 Github 问题。

- Axeman

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谢谢你的回答 - 我会提交一个问题。 - Jane

我已经发布了另一个答案。感谢您的评论！ - Jane