如何使用 ggplot 有条件地在美国地图上着色？

Posted 2023-02-16

【中文标题】如何使用 ggplot 有条件地在美国地图上着色？

【英文标题】：How do I conditionally color in a US States map using ggplot?

【发布时间】：2021-11-23 06:21:07

【问题描述】：

我的目标是将低于销售平均水平的状态显示为红色，将高于平均水平的状态显示为绿色。我的代码似乎只是在做某种颜色的轮廓，我不知道蓝色填充是从哪里来的。实际数据包含所有状态，但为此我仅举了 5 个示例。

    library(ggplot2)
    library(tidyverse)
    library(mapdata)
    library(dplyr)
    
    MainStates <- map_data("state")
    State_Name <- c("alabama","arkansas","arizona","california","colorado")
    Sales <- c(100,200,250,275,310)
    df2 <- data.frame(State_Name,Sales)
    MergedStates <- inner_join(MainStates, df2, by = c("region" = "State_Name"))

    p <- ggplot() + geom_polygon(data = MergedStates,
                         aes(x=long, y=lat, group=group, fill=Sales),
                         color = ifelse(MergedStates$Sales <= 
                         mean(MergedStates$Sales),"red","green"), size = 0.2)
    p

【参考方案1】：

我想这就是你想要达到的目标？在geom_sf 中，color 指的是边框的颜色，fill 指的是填充多边形的颜色（对于多边形）。

library(ggplot2)
library(tidyverse)
library(mapdata)
#> Loading required package: maps
#> 
#> Attaching package: 'maps'
#> The following object is masked from 'package:purrr':
#> 
#>     map
library(dplyr)

MainStates <- map_data("state")
State_Name <- c("alabama","arkansas","arizona","california","colorado")
Sales <- c(100,200,250,275,310)
df2 <- data.frame(State_Name,Sales)
MergedStates <- inner_join(MainStates, df2, by = c("region" = "State_Name"))

p <- ggplot() + geom_polygon(data = MergedStates,
                             aes(x=long, y=lat, group=group),
                             fill = ifelse(MergedStates$Sales <= 
                                              mean(MergedStates$Sales),"red","green"), size = 0.2)
p

^{由reprex package (v2.0.1) 于 2021 年 10 月 1 日创建}