如何在ggplot中制作分年度对比的分组发散条形图？

方案1：同一图中交错排列年份条形 #

通过在数据分组时加入year维度，使用interaction(role, year)作为x轴变量，配合position_dodge()实现同角色下两年条形的并排交错。

修改后的完整代码：

# 调整数据汇总：按role、define、year分组
support_sum <- support %>% 
  group_by(role, define, year) %>%  # 新增year分组
  count(name = "n_support") %>% 
  group_by(role, year) %>%  # 按role和year计算百分比
  mutate(percent_support = n_support / sum(n_support)) %>% 
  ungroup() %>% 
  mutate(percent_support_labels = percent(percent_support, accuracy = 1))

# 设置发散格式，保留year维度
support_sum_div <- support_sum %>%
  mutate(percent_support = if_else(define %in% c("Strongly Agree", "Agree"), percent_support, -percent_support)) %>% 
  mutate(percent_support_labels = percent(percent_support, accuracy = 1))

# 修正标签为绝对值百分比
support_sum_div_labs <- support_sum_div %>%
  mutate(percent_support_labels = abs(percent_support)) %>% 
  mutate(percent_support_labels = percent(percent_support_labels, accuracy = 1))

# 重新排序define因子，创建role+year交互变量
support_div_ordered <- support_sum_div_labs %>% 
  mutate(define = fct_relevel(define,
                               "Neutral", "Strongly Disagree", "Disagree", "Agree", "Strongly Agree"),
         define = fct_rev(define),
         role_year = interaction(role, year, sep = " - "))

# 绘制交错条形的发散图
support_div_ordered %>%
  ggplot(aes(x = role_year, 
             y = percent_support,
             fill = define)) +
  geom_col(position = position_dodge(width = 0.8), width = 0.7) +  # 启用dodge实现并排
  geom_text(aes(label = percent_support_labels),
            position = position_dodge(width = 0.8),  # 文本位置匹配dodge
            vjust = 0.5,
            color = "white",
            fontface = "bold",
            size = 3) +
  coord_flip() +
  scale_fill_manual(breaks = c("Neutral", "Strongly Disagree", "Disagree", "Agree", "Strongly Agree"),
                    values = c(
                      "Neutral" = "gold",
                      "Strongly Disagree" = "slateblue",
                      "Disagree" = "plum",
                      "Agree" = "#41b6c4",
                      "Strongly Agree" = "dodgerblue4"
                    )) +
  labs(title = "People are supportive of each other (2021 vs 2023)",
       x = "Role - Year",
       fill = NULL) +
  theme_minimal() +
  theme(axis.title.x = element_blank(),
        panel.grid = element_blank(),
        legend.position = "top")

方案2：对齐拆分图的中线 #

确保两张独立图的x轴范围完全一致，并用cowplot::plot_grid的align参数实现水平对齐，同时统一图表元素（如标题、轴标签）。

修改后的代码示例：

# 定义通用绘图函数，避免重复代码
plot_diverge <- function(data, year_label) {
  data %>%
    ggplot(aes(x = role, 
               y = percent_support,
               fill = define)) +
    geom_col() +
    geom_text(aes(label = percent_support_labels),
              position = position_stack(vjust = 0.5),
              color = "white",
              fontface = "bold") +
    coord_flip(xlim = c(0, length(unique(data$role)) + 0.5)) +  # 设置统一x轴范围
    scale_fill_manual(breaks = c("Neutral", "Strongly Disagree", "Disagree", "Agree", "Strongly Agree"),
                      values = c(
                        "Neutral" = "gold",
                        "Strongly Disagree" = "slateblue",
                        "Disagree" = "plum",
                        "Agree" = "#41b6c4",
                        "Strongly Agree" = "dodgerblue4"
                      )) +
    labs(title = paste("Support in", year_label),
         x = NULL,
         fill = NULL) +
    theme_minimal() +
    theme(axis.text.x = element_blank(),
          axis.title.x = element_blank(),
          panel.grid = element_blank(),
          legend.position = "none")  # 只在一张图显示图例
}

# 拆分数据并绘图
support_2021 <- support_div_ordered %>% filter(year == 2021)
support_2023 <- support_div_ordered %>% filter(year == 2023)

plot_2021 <- plot_diverge(support_2021, "2021")
plot_2023 <- plot_diverge(support_2023, "2023") + theme(legend.position = "top")  # 保留一个图例

# 对齐合并图表
plot_grid(plot_2023, plot_2021, align = "h", ncol = 2) +
  labs(title = "People are supportive of each other (2021 vs 2023)")

内容的提问来源于stack exchange，提问作者Kiirsti Owen