如何在ggplot2中调整Y轴标签，仅保留子类别信息？

问题描述 #

使用interaction(Sub_Category, Category)作为Y轴变量时，Y轴标签会显示Sub_Category.Category的组合形式（如Brown.Bread），需求是仅显示Sub_Category名称，类别信息由图例展示，且方案需适配多类别/子类别场景。

解决方案 #

核心思路是直接将Sub_Category作为Y轴变量，通过position_dodge参数控制同子类别下不同类别的柱子并排，同时保留原有的轴顺序。修改后的完整代码如下：

# Load libraries and data.
library(tidyverse)

df <- data.frame(
    Product = c(755, 728, 417, 355, 913, 634, 385, 208, 204, 696, 968, 816, 279, 869, 823, 646, 986, 674, 806, 335, 731, 734, 107, 105, 512, 859, 159, 113, 353, 105, 205, 919, 243, 717, 838, 408, 423, 357, 408, 464, 724, 643, 943, 648, 623, 451, 449, 135, 842, 711),
    Category = c("Bread", "Cheese", "Bread", "Cheese", "Bread", "Cheese", "Bread", "Bread", "Bread", "Cheese", "Bread", "Bread", "Cheese", "Bread", "Cheese", "Bread", "Bread", "Bread", "Cheese", "Cheese", "Cheese", "Bread", "Bread", "Cheese", "Bread", "Cheese", "Bread", "Bread", "Bread", "Cheese", "Cheese", "Bread", "Bread", "Cheese", "Cheese", "Bread", "Bread", "Bread", "Bread", "Cheese", "Cheese", "Cheese", "Cheese", "Cheese", "Cheese", "Cheese", "Cheese", "Bread", "Bread", "Cheese"),
    Sub_Category = c("White", "Camembert", "White", "Camembert", "White", "Brie", "Brown", "Wholemeal", "White", "Brie", "Wholemeal", "Wholemeal", "Gouda", "Wholemeal", "Camembert", "Brown", "White", "Wholemeal", "Gouda", "Gouda", "Brie", "Wholemeal", "Wholemeal", "Camembert", "White", "Brie", "Wholemeal", "Wholemeal", "Brown", "Brie", "Brie", "White", "Wholemeal", "Camembert", "Gouda", "White", "Wholemeal", "Brown", "White", "Camembert", "Brie", "Brie", "Camembert", "Brie", "Camembert", "Gouda", "Camembert", "Wholemeal", "White", "Camembert"),
    Fibre = c(TRUE, FALSE, FALSE, FALSE, FALSE, TRUE, FALSE, TRUE, FALSE, FALSE, TRUE, FALSE, FALSE, FALSE, TRUE, FALSE, FALSE, FALSE, TRUE, TRUE, TRUE, FALSE, FALSE, FALSE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, TRUE, FALSE, FALSE, TRUE, FALSE, TRUE, TRUE, TRUE, TRUE, TRUE, FALSE, TRUE, FALSE, FALSE, FALSE, FALSE, TRUE, FALSE, TRUE, TRUE)
)

# Organise data for plotting.
proportions <- df %>%
  group_by(Category, Sub_Category) %>%
  summarise(Proportion = mean(Fibre == TRUE) * 100, .groups = 'drop')

# Plot data with modified Y-axis
ggplot(data = proportions, 
       aes(x = Proportion, 
           y = Sub_Category, 
           fill = Category)
       ) +
  geom_col(position = position_dodge(width = 0.9)) +  # 控制同子类别下柱子的间距
  scale_y_discrete(limits = rev(unique(proportions$Sub_Category))) +  # 保留原有的反转顺序
  labs(fill = "Category", y = "Sub Category")

关键修改说明 #

• Y轴变量替换：将y = interaction(Sub_Category, Category)改为y = Sub_Category，直接使用子类别作为Y轴标签。
• 调整柱子并排：使用position_dodge(width = 0.9)替代position = "dodge"，确保同一子类别下的不同类别柱子完全并排（width参数可根据需求微调）。
• 保留轴顺序：通过rev(unique(proportions$Sub_Category))获取原数据中子类别的唯一值并反转，保持与原图表一致的Y轴顺序，无需手动指定标签。

内容的提问来源于stack exchange，提问作者Jay Bee