为 geom_raster 和 geom_path 添加单独的图例

Question

我正在绘制一个栅格并用两个多边形覆盖它。我想分别为每个 shapefile 绘制图例（即缓冲区图例和每个多边形的一个图例）。我在 geom_path 中使用了 show.legend = TRUE 但它没有给我我想要的东西。我正在使用此代码。

gplot(pfiles) + 
  geom_raster(aes(fill = factor(value))) +
  geom_path(data=ward, aes(long, lat, group=group), color = "black") +
  geom_path(data=buffer, aes(long, lat, group=group), color = "red") +
  facet_wrap(~ variable, ncol = 4) +
  scale_fill_manual(values = c("darkorchid", "chartreuse3", "cornflowerblue", "goldenrod2"), 
                      na.value="transparent", na.translate = F) +
  guides(fill = guide_legend(title = "Buffer Zones")) +
  #scale_color_identity(guide = "legend") +
  theme_bw() +
  theme(axis.text = element_blank(), legend.position = "right", legend.direction = "vertical",
        axis.title = element_blank(),
        legend.key.height = unit(2, "cm"), legend.key.width = unit(1, "cm"),
        legend.title = element_text(size = 22, face = "bold"), legend.text = element_text(size = 20), 
        strip.text = element_text(size = 18, face = "bold"),
        plot.title = element_text(size = 20, face = "bold"),
        plot.subtitle = element_text(size = 15), plot.caption = element_text(size = 12, face = "bold.italic"),
        panel.background = element_rect(fill = "transparent")) +
  labs(title = "Variables for Identification of Potential Urban Development Zones",
       subtitle = "Land Price and Ground Water Level represent price and water depth respectively; Others represent Euclidean Distance") +
  coord_equal()

Answer 1

在 ggplot2 中 geoms 没有图例。相反，传说反映了美学或规模。 geom 仅确定图例中使用的键的形状，例如a geom_point 会被描绘成一个点，a geom_path 会被描绘成一条线，... 这就是说，如果你想有一个传奇，你必须在美学上进行映射。

要获得描述不同颜色 geom_path 的图例，您可以在 color 美学上映射一个常量值，然后使用 scale_color_manual 将您想要的颜色分配给这些常量。

以下代码未经测试，但应该会给您想要的结果：

ggplot(pfiles) +
  geom_raster(aes(fill = factor(value))) +
  geom_path(data = ward, aes(long, lat, group = group, color = "ward")) +
  geom_path(data = buffer, aes(long, lat, group = group, color = "buffer")) +
  scale_color_manual(values = c(ward = "black", buffer = "red"))

为 geom_raster 和 geom_path 添加单独的图例

Add separate legend for geom_raster and geom_path

r

ggplot2

geom-raster