问题

我正在使用ggplot2来可视化与地图相关的数据。我已根据连续值对区域进行了着色，并希望添加一个带有颜色和区域名称的图例。我的数据有点复杂，不太方便共享，但我已经使用公共数据（ggplot2中的地图绘制）重新创建了这种情况。以下代码创建了包含的地图：

library(ggplot2)
library(sf)

# 导入一个geojson或shapefile
map <- read_sf("https://raw.githubusercontent.com/R-CoderDotCom/data/main/shapefile_spain/spain.geojson")

ggplot(map) +
  geom_sf(color = "white", aes(fill = unemp_rate)) +
  geom_sf_text(aes(label = name), size = 2)

代替连续默认图例，我想要一个具有名称、数字和颜色的图例。基本上，一个图例显示数据的name和unemp_rate列，颜色与地图匹配（例如unemp_rate）。有点类似于第二张包含的图片的图例（但颜色不正确）。

实际代码如下：

ggplot(map, aes(geometry = geometry, fill = Y1)) +
  theme_bw() + geom_sf(show.legend = FALSE) +
  scale_fill_gradient2(low = "brown", high = "green") +
  theme(
    axis.title = element_blank(),
    axis.text = element_blank(),
    axis.ticks = element_blank())

library(ggplot2)
library(sf)

# Import a geojson or shapefile
map <- read_sf("https://raw.githubusercontent.com/R-CoderDotCom/data/main/shapefile_spain/spain.geojson")

ggplot(map) +
  geom_sf(color = "white", aes(fill = unemp_rate)) +
  geom_sf_text(aes(label = name), size = 2)

ggplot(map, aes(geometry = geometry, fill = Y1)) +
  theme_bw() + geom_sf(show.legend = FALSE) +
  scale_fill_gradient2(low = "brown", high = "green") +
  theme(
    axis.title = element_blank(),
    axis.text = element_blank(),
    axis.ticks = element_blank())

答案1

得分: 2

也许可以考虑使用嵌套的条形图代替：

library(ggplot2)
library(sf)
library(dplyr)
library(patchwork)
# 导入一个geojson或shapefile
map_ <- read_sf("https://raw.githubusercontent.com/R-CoderDotCom/data/main/shapefile_spain/spain.geojson") %>%
  mutate(name = forcats::fct_reorder(name, desc(unemp_rate)))

g1 <- map_ %>%
  ggplot() +
  geom_sf(color = "white", aes(fill = unemp_rate)) +
  geom_sf_text(aes(label = name), size = 2) +
  scale_fill_gradient2(low = "brown", high = "green", midpoint = 16) +
  theme_minimal() +
  theme(legend.position = "none", axis.text = element_blank(), axis.title = element_blank(), panel.grid = element_blank())

g2 <- map_ %>%
  ggplot(aes(x = unemp_rate, y = name, fill = unemp_rate)) +
  geom_col() + 
  scale_fill_gradient2(low = "brown", high = "green", midpoint = 16) +
  geom_text(aes(label = name, x = .5, hjust = 0)) +
  geom_text(aes(label = unemp_rate), nudge_x = - .5, hjust = 1) +
  theme_void() +
  theme(legend.position = "none")

g1 + inset_element(g2, 0, .2, .9, 1)

<details>
<summary>英文:</summary>

Perhaps an inset bar chart instead:

library(ggplot2)
library(sf)
library(dplyr)
library(patchwork)

Import a geojson or shapefile

map_ <- read_sf("https://raw.githubusercontent.com/R-CoderDotCom/data/main/shapefile_spain/spain.geojson") %>%
mutate(name = forcats::fct_reorder(name, desc(unemp_rate)))

g1 <- map_ %>%
ggplot() +
geom_sf(color = "white", aes(fill = unemp_rate)) +
geom_sf_text(aes(label = name), size = 2) +
scale_fill_gradient2(low = "brown", high = "green", midpoint = 16) +
theme_minimal() +
theme(legend.position = "none", axis.text = element_blank(), axis.title = element_blank(), panel.grid = element_blank())

g2 <- map_ %>%
ggplot(aes(x = unemp_rate, y = name, fill = unemp_rate)) +
geom_col() +
scale_fill_gradient2(low = "brown", high = "green", midpoint = 16) +
geom_text(aes(label = name, x = .5, hjust = 0)) +
geom_text(aes(label = unemp_rate), nudge_x = - .5, hjust = 1) +
theme_void() +
theme(legend.position = "none")

g1 + inset_element(g2, 0, .2, .9, 1)

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/ZeQN2.png

</details>



# 答案2
**得分**: 1

这有点复杂，因为这是一种非常非标准的制作图例的方式，但使用`scales`包的帮助并不太难。您可以首先创建自己的颜色比例尺，例如：

```R
library(scales)
my_pal <- seq_gradient_pal(low = 'brown', high = 'green')
my_scale <- col_numeric(palette = my_pal, domain = range(map$unemp_rate))
my_cols <- setNames(my_scale(map$unemp_rate), map$name)

然后使用以下代码创建图表：

ggplot(map) +
  geom_sf(color = "white", aes(fill = name)) +
  geom_sf_text(aes(label = name), size = 2) +
  scale_fill_manual(
    values = my_cols,
    name = "失业率",
    labels = setNames(paste(map$name, map$unemp_rate, sep = ': '), map$name)
  )

library(scales)
my_pal <- seq_gradient_pal(low = 'brown', high = 'green')
my_scale <- col_numeric(palette = my_pal, domain = range(map$unemp_rate))
my_cols <- setNames(my_scale(map$unemp_rate), map$name)

ggplot(map) +
  geom_sf(color = "white", aes(fill = name)) +
  geom_sf_text(aes(label = name), size = 2) +
  scale_fill_manual(
    values = my_cols,
    name = "Unemployment rate",
    labels = setNames(paste(map$name, map$unemp_rate, sep = ': '), map$name)
  )

答案3

得分: 0

你需要创建一个字段，将名称和失业率合并，并将其用作填充变量。另外，我不确定关于“颜色不对”的部分，但也许你想要一个连续的颜色比例尺？所以我正在使用viridis颜色调色板来获取类似的连续比例尺，但适用于分类数据。

map |> 
    mutate(fill_var = paste0(name, ' - ', unemp_rate)) |> 
    ggplot() +
    geom_sf(color = "white", aes(fill = fill_var)) +
    geom_sf_text(aes(label = name), size = 2) + 
    ggthemes::theme_map() + # optional
    scale_fill_viridis_d() + 
    labs(fill = "")

<details>
<summary>英文:</summary>

You need to create a field which combines the name and unemployment rate and use that for the fill variable. Also I am not sure about the &quot;colours are not right&quot; part, but maybe you want a continuous colour scale? So I am using viridis colour palette to get similar continuous scale but for categorical data. 

    map |&gt; 
        mutate(fill_var = paste0(name, &#39; - &#39;, unemp_rate)) |&gt; 
        ggplot() +
        geom_sf(color = &quot;white&quot;, aes(fill = fill_var)) +
        geom_sf_text(aes(label = name), size = 2) + 
        ggthemes::theme_map() + # optional
        scale_fill_viridis_d() + 
        labs(fill = &quot;&quot;)

[![sample_plot_output_with_legends][1]][1]


  [1]: https://i.stack.imgur.com/j6VOf.png

</details>