ggmap图例未显示

Question

我有两个数据记录，两个记录前10个站的骑手去了。一个是休闲骑手，另一个是会员骑手。这两种数据都包含“工作站”、“freq”、“纬度”、“经度”列。我可以用ggmap来绘制图表，从两个数据中显示站的位置，但不能显示传奇。R条如下所示：

library(ggplot2)
library(rstudioapi)
library(ggmap)

map_location <- c (lon =  -87.623177, lat = 41.881832)

chicago_map_zoom <- get_map (location = map_location, 
                        maptype = 'roadmap', 
                        color='bw', 
                        source='google', 
                        zoom=13,
)

chicago_plot <- ggmap(chicago_map_zoom) +
  geom_point (data = casual_top_station,
              aes (x = longitude,
                   y = latitude),
              color = "red",
              shape = 15,
              alpha = 0.5,
              size = 3) +
  geom_point (data = member_top_station,
              aes (x = longitude,
                   y = latitude),
              color = "blue",
              shape = 16,
              alpha = 0.5,
              size = 2) +
  scale_color_identity (name = "Subscription type",
                        breaks = c("red","blue"),
                        labels = c("Casual","Member"),
                        guide = "legend") +
  theme (axis.ticks = element_blank(),
         axis.text = element_blank(),
         axis.title = element_blank()) +
  labs (title = "Top 10 casual and member rider stations",
        subtitle = "Both start and end stations")

结果图：地图

Answer 1

而不是使用scale_color_identity。为了设置颜色、形状和大小的值，我建议首先将id列设置为data.frames，然后将其映射到aes内部的美学上。然后，通过scale_xxx_manual系列函数设置所需的颜色、形状和大小。

用一些假数据来表示要点：

library(ggplot2)
library(ggmap)

casual_top_station <- data.frame(
  longitude = -87.65,
  latitude = 41.9
)

member_top_station <- data.frame(
  longitude = -87.65,
  latitude = 41.86
)

casual_top_station$id <- "Casual"
member_top_station$id <- "Member"
legend_title <- "Subscription type"

base <- ggmap(chicago_map_zoom) +
  scale_color_manual(values = c(Casual = "red", Member = "blue")) +
  scale_shape_manual(values = c(Casual = 15, Member = 16)) +
  scale_size_manual(values = c(Casual = 3, Member = 2)) +
  theme(
    axis.ticks = element_blank(),
    axis.text = element_blank(),
    axis.title = element_blank()
  ) +
  labs(
    title = "Top 10 casual and member rider stations",
    subtitle = "Both start and end stations",
    color = legend_title, shape = legend_title, size = legend_title
  )

base + 
  geom_point(
    data = casual_top_station,
    aes(
      x = longitude,
      y = latitude,
      color = id, shape = id, size = id
    ),
    alpha = 0.5
  ) +
  geom_point(
    data = member_top_station,
    aes(
      x = longitude,
      y = latitude,
      color = id, shape = id, size = id
    ),
    alpha = 0.5
  )

​

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此外，为了进一步简化代码，我建议使用例如dplyr::bind_rows按行绑定两个数据框架，这将允许仅通过一个geom_point添加点。

top_station <- dplyr::bind_rows(casual_top_station, member_top_station)

base + 
  geom_point(
    data = top_station,
    aes(
      x = longitude,
      y = latitude,
      color = id, shape = id, size = id
    ), alpha = .5)

​

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