ggplot堆叠条形图：调整方向、设置嵌套Y轴标签及显示条形数值

要实现Sales在X轴，Year与Category在Y轴区域的水平堆叠条形图，并显示每个堆叠块的销售数值，可通过两种方式调整：

方式1：合并Year与Category为Y轴变量 #

直接将Year和Category组合成单个Y轴分类变量，无需分面，直观展示两者的组合关系：

library(ggplot2)

data2 <- read.table(text = "Product Category Year Sales
               A Clothing 2017 100
               A Clothing 2018 120
               A Electronics 2017 150
               A Electronics 2018 200
               A Food 2017 50
               A Food 2018 80
               B Clothing 2017 80
               B Clothing 2018 90
               B Electronics 2017 100
               B Electronics 2018 120
               B Food 2017 70
               B Food 2018 100", header=TRUE)

# 生成Year+Category的组合Y轴变量
data2$Y_label <- paste(data2$Year, data2$Category, sep = " - ")

# 绘制水平堆叠条形图
ggplot(data2, aes(y = Y_label, x = Sales, fill = Product)) +
  geom_bar(stat = "identity", position = "stack") +
  # 添加居中的销售数值标签
  geom_text(aes(label = Sales), position = position_stack(vjust = 0.5), size = 3) +
  labs(x = "Sales", y = "Year - Category") +
  theme(
    panel.background = element_rect(fill = "white", colour = "white"),
    axis.line = element_line(colour = "grey"),
    panel.grid.major.x = element_line(colour = "grey")
  )

方式2：用分面调整Category到Y轴区域 #

如果需要保留Year和Category的独立展示，可使用facet_grid替代facet_wrap，并通过switch="y"将Category标签移到Y轴左侧，配合coord_flip实现需求：

library(ggplot2)

data2 <- read.table(text = "Product Category Year Sales
               A Clothing 2017 100
               A Clothing 2018 120
               A Electronics 2017 150
               A Electronics 2018 200
               A Food 2017 50
               A Food 2018 80
               B Clothing 2017 80
               B Clothing 2018 90
               B Electronics 2017 100
               B Electronics 2018 120
               B Food 2017 70
               B Food 2018 100", header=TRUE)

ggplot(data2, aes(x = Year, y = Sales, fill = Product)) +
  geom_bar(stat = "identity") +
  geom_text(aes(label = Sales), position = position_stack(vjust = 0.5), size = 3) +
  # 将Category作为行分面，并把标签切换到Y轴左侧
  facet_grid(Category ~ ., switch = "y") +
  coord_flip() +
  labs(y = "Sales", x = "") +
  theme(
    panel.spacing = unit(0, "lines"),
    strip.background = element_blank(),
    axis.line = element_line(colour = "grey"),
    panel.grid.major.x = element_line(colour = "grey"),
    strip.placement = "outside",
    panel.background = element_rect(fill = "white", colour = "white")
  )

原代码问题说明 #

你之前使用facet_wrap(vars(Category), strip.position = "bottom")配合coord_flip时，strip会被翻转到图表右侧，而非Y轴区域。改用facet_grid并设置switch="y"，能让Category标签直接与Year的Y轴刻度对齐，满足需求。

内容的提问来源于stack exchange，提问作者Jess H