如何用ggplot2绘制分国家的NUTS2层级水平条形分面网格图？

原始数据 #

data <- data.frame(
  nuts = c("AT11", "AT11", "AT11", "AT12", "AT12", "AT12",
           "AT13", "AT13", "AT13", "AT21", "AT21", "AT21",
           "DE11", "DE11", "DE11", "DE12", "DE12", "DE12"),
  type = c("all", "flat", "house", "all", "flat", "house",
           "all", "flat", "house", "all", "flat", "house",
           "all", "flat", "house", "all", "flat", "house"),
  year = c(2007, 2007, 2007, 2007, 2007, 2007,
           2000, 2000, 2000, 2007, 2007, 2007,
           2007, 2007, 2007, 2007, 2007, 2007))

第一步：数据预处理 #

从nuts编码中提取国家代码（前两位），为后续分面做准备：

library(ggplot2)

# 提取国家代码（AT=奥地利，DE=德国）
data$country <- substr(data$nuts, 1, 2)

第二步：绘制分面水平条形图 #

按照需求实现每个国家一个分面，y轴为NUTS2编码，x轴为年份，不同建筑类型用颜色区分：

ggplot(data, aes(x = factor(year), y = nuts, fill = type)) +
  # 同一NUTS2下的不同建筑类型条形并列展示
  geom_col(position = position_dodge(width = 0.8), width = 0.7) +
  # 按国家分面，每个国家的y轴仅显示自身的NUTS2编码
  facet_wrap(~country, scales = "free_y", ncol = 1) +
  # 设置坐标轴标签和标题
  labs(x = "数据可用年份", y = "NUTS2区域编码", fill = "建筑类型",
       title = "不同国家NUTS2区域建筑类型数据年份分布") +
  # 优化主题提升可读性
  theme_minimal() +
  theme(
    plot.title = element_text(hjust = 0.5, size = 14, face = "bold"),
    axis.text = element_text(size = 10),
    legend.position = "bottom"
  )

代码说明 #

• position_dodge(width=0.8)：避免同一NUTS2下的三种建筑类型条形重叠，实现并列展示
• facet_wrap(~country, scales="free_y")：每个国家单独成面，且y轴仅显示当前国家的NUTS2编码，排除无关区域干扰
• factor(year)：将年份转为离散值，适配条形图的x轴展示逻辑

展示国家数据年份差异的更优方式 #

除分面条形图外，以下两种方式能更直观呈现年份差异：

1. 热图（Tile Plot） #

用色块展示每个NUTS2区域的可用年份，快速识别年份覆盖差异：

ggplot(data, aes(x = factor(year), y = nuts, fill = type)) +
  geom_tile(color = "white", size = 0.5) +
  facet_wrap(~country, scales = "free_y", ncol = 1) +
  labs(x = "数据可用年份", y = "NUTS2区域编码", fill = "建筑类型",
       title = "不同国家NUTS2区域数据年份覆盖热图") +
  theme_minimal() +
  theme(
    plot.title = element_text(hjust = 0.5, size = 14, face = "bold"),
    axis.text = element_text(size = 10),
    legend.position = "bottom"
  )

这种方式能一眼看出哪些区域存在年份缺失（比如奥地利AT13仅2000年有数据，其他区域均为2007年）。

2. 带年份汇总标注的分面图 #

在分面顶部添加国家的年份范围标注，强化差异感知：

# 计算每个国家的年份范围
year_summary <- aggregate(year ~ country, data, function(x) paste(range(x), collapse = " - "))
names(year_summary)[2] <- "year_range"

# 绘制带标注的分面图
ggplot(data, aes(x = factor(year), y = nuts, fill = type)) +
  geom_col(position = position_dodge(width = 0.8), width = 0.7) +
  facet_wrap(~country, scales = "free_y", ncol = 1) +
  # 添加年份范围标注
  geom_text(data = year_summary, aes(x = Inf, y = Inf, label = year_range),
            hjust = 1.1, vjust = 1.5, size = 4, fontface = "italic") +
  labs(x = "数据可用年份", y = "NUTS2区域编码", fill = "建筑类型",
       title = "不同国家NUTS2区域建筑类型数据年份分布（含年份范围）") +
  theme_minimal() +
  theme(
    plot.title = element_text(hjust = 0.5, size = 14, face = "bold"),
    axis.text = element_text(size = 10),
    legend.position = "bottom"
  )

内容的提问来源于stack exchange，提问作者Tim George