ggplot2自定义地图边界线颜色

library(tidyverse)
library(lubridate)
library(scales)

languages <- read_tsv("languages.xls")
language_countries <- read_tsv("language_countries.xls")
country_regions <- read_tsv("country_regions.xls")

language_countries2 <- language_countries |> 
  left_join(languages, by = "language_iso_code")

target_map <- map_data("world") |> 
  mutate(region = if_else(region == "Swaziland", "Eswatini", region)) |> 
  semi_join(country_regions, by = c("region" = "country")) |> 
  left_join(language_countries2,
            by = c("region" = "country"), multiple = "all")

map_data("world") |> 
 filter(long > -20, long < 60, lat > -40, lat < 40) |> 
  ggplot(aes(long, lat)) +
  # 绘制基础地图路径
  geom_path(aes(group = group), color = "gray80") +
# 设置颜色填充
  geom_polygon(aes(group = group, fill = language),
               data = target_map |>
                 filter(!language_iso_code %in% c("tso", "hau", "pcm", "swa")) |> 
                 mutate(language = if_else(language_iso_code %in% c("ibo", "yor"), "Igbo / Yorùbá", language))) +
# 绘制边界线
  geom_path(aes(group = group, color = language), 
            linewidth = 1, alpha = 1/2,
            data = target_map |> 
              filter(language_iso_code %in% c("tso", "hau", "pcm", "swa")) |> 
              mutate(language = if_else(language_iso_code %in% c("hau", "pcm"),
                                           "Hausa / Nigerian Pidgin",
                                           language))) +
  # 设置颜色和图例
  scale_fill_brewer("Single-country language", palette = "Paired") +
  scale_color_manual("Multi-country language", values = c("#E6956F", "#788FCE", "green")) +
  # 设置地图坐标
  coord_map() +
  # 设置主题
  theme_void() +
  theme(plot.background = element_rect(fill = "white", color = "white"))