如何用R语言ggplot2绘制六边形瓦片网格地图

核心思路 #

要将矩形瓦片转为六边形，需要调整坐标实现交错排列，并使用支持六边形绘制的geom图层。这里推荐用ggforce包的geom_hexagon，它能直接生成规则六边形，无需手动绘制多边形顶点。

修改步骤 #

1. 安装并加载ggforce包：如果还没安装，先执行安装命令，再加载包。
2. 调整坐标偏移：六边形网格需要奇数行的x坐标偏移0.5，让瓦片能交错对齐。
3. 替换图层：把geom_tile换成geom_hexagon，同时调整文本的x坐标映射，保证文字居中在六边形内。

修改后的完整代码 #

library(tidyverse)
library(ggplot2)
library(tidytuesdayR)
library(highcharter)
library(maps)
library(jsonlite)
library(showtext)
library(showtextdb)
library(ggtext)
library(ggforce) # 新增：加载ggforce包

world_grid <- read_csv("worldtilegrid.txt")
tt <- tidytuesdayR::tt_load('2023-05-30')
tt <- tt$centenarians 

countries_count <- tt %>%
  group_by(place_of_death_or_residence) %>%
  mutate(place_of_death_or_residence = case_when(place_of_death_or_residence == "France (French Guiana)" ~ "France",
                                                 place_of_death_or_residence == "France (Martinique)" ~ "France",
                                                 place_of_death_or_residence == "France (Saint Barthélemy)" ~ "France",
                                                 place_of_death_or_residence == "United States" ~ "United States of America",
                                                 place_of_death_or_residence == "United Kingdom" ~ "Great Britain and Northern Ireland",
                                                 place_of_death_or_residence == "Puerto Rico" ~ "United States of America",
                                                 TRUE ~ place_of_death_or_residence)) %>%
  summarise(count = n()) %>%
  as.data.frame()
  
data_to_plot <- world_grid %>%
  left_join(countries_count, by = c("name" = "place_of_death_or_residence")) %>%
  # 新增：调整x坐标，奇数行偏移0.5，适配六边形交错排列
  mutate(x_hex = ifelse(y %% 2 == 1, x + 0.5, x))

plot <- ggplot() +
  # 替换geom_tile为geom_hexagon，设置半径，映射调整后的x坐标
  geom_hexagon(data = data_to_plot, aes(x = x_hex, y = y, fill = count), 
               color = "#ffffff", radius = 0.5) +
  # 文本的x坐标也用调整后的x_hex，保证居中
  geom_text(data = data_to_plot, aes(x = x_hex, y = y, label = alpha.2), 
            color = "#ffffff", alpha = 0.5, family = "caption", size = 25) +
  scale_y_reverse() + 
  scale_fill_continuous(na.value = "gray", low = "#7F3C8D", high = "#80BA5A", guide = "colorbar") +
  theme_void() +
  labs(fill = "Count",
       title = "Verified Oldest People Around the World",
       subtitle = "This map demonstrates the distribution of the place of birth or residence<br>of the verified 100 oldest people across countries.") +
  theme(plot.title = element_markdown(size = 110, hjust = 0.5, family = "plottitle", linewidth = 0.1),
        plot.subtitle = element_markdown(size = 80, hjust = 0.5, family = "title", lineheight = 0.2),
        plot.background = element_rect(fill = "#dedad2", color = NA),
        panel.border = element_blank(),
        legend.title = element_markdown(size = 65, family = "caption", vjust = 0.75),
        legend.text = element_text(size = 40, family = "caption"),
        legend.spacing.x = unit(0.2, 'cm'),
        legend.spacing.y = unit(0.2, 'cm'),
        legend.direction = "horizontal",
        legend.position = c(0.2, 0.2))

# 查看绘图
plot

关键说明 #

• geom_hexagon的radius设为0.5，刚好和原矩形瓦片的尺寸匹配，保证瓦片之间紧密排列。
• 奇数行x偏移0.5是六边形网格的标准布局方式，能避免瓦片重叠，实现交错效果。
• 文本的x坐标同步调整，确保每个国家的缩写文字刚好落在六边形中心。

内容的提问来源于stack exchange，提问作者mzkrc