Shiny中实现可选择变量的双柱状图绘制及标签动态更新

问题需求 #

需要实现：

• X轴为国家，每个国家展示固定的x54（平均月薪）和通过下拉框选择的x48/x49（不同位置的单间房租）双柱形
• 图例标签根据所选变量自动切换对应描述

修改后的完整代码 #

library(shiny)
library(ggplot2)
library(tidyverse)

# 加载数据集（可替换为你的本地读取代码）
df <- structure(list(
  country = c("Andorra", "Austria", "Belgium", "Denmark", "Finland", "France", "Germany", "Greece"),
  x48 = c(811.73, 710.0385, 765.8359, 961.434, 701.9176, 716.7308, 701.6187, 468.1942),
  x49 = c(655.2433, 607.8058, 628.3675, 692.426, 575.4287, 587.7711, 544.2052, 370.2103),
  x54 = c(2801.597, 2224.757, 2320.216, 3130.023, 2582.625, 2399.011, 2621.368, 804.5603)
), class = "data.frame", row.names = c(NA, -8L))

ui = fluidPage(
  titlePanel("Salary vs. Rent Comparison"),
  sidebarLayout(
    sidebarPanel(
      # 下拉框显示友好标签，传递对应变量名
      selectInput("x1", "Type of house rent:", 
                  choices = c("x48" = "1 room in the center", 
                              "x49" = "1 room outside the center"),
                  selected = "x48")
    ),
    mainPanel(
      plotOutput("plot")
    )
  )
)

server = function(input, output) {
  output$plot <- renderPlot({
    # 变量-标签映射表
    label_map <- c(
      "x48" = "1 room in the center",
      "x49" = "1 room outside the center",
      "x54" = "Average Monthly Salary"
    )
    
    # 变量-颜色映射表，保证颜色一致性
    color_map <- c(
      "x48" = "#DA560A",
      "x49" = "#DA560A",
      "x54" = "#58C114"
    )
    
    df_long <- df %>% pivot_longer(-country)
    
    ggplot(data = df_long %>% filter(name %in% c(input$x1, "x54")),  
           aes(x = country, y = value, fill = factor(name))) +
      geom_col(position = position_dodge(width = 0.8)) +
      # 动态匹配标签和颜色，不受数据顺序影响
      scale_fill_manual(values = color_map, 
                        labels = label_map,
                        name = "Metric") +
      theme_light() +
      theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust = 1)) +
      labs(x= "Country", y= "USD")
  })
}

# 运行应用
shinyApp(ui, server)

核心修改说明 #

1. 下拉框逻辑优化：

   • 仅提供x48/x49作为可选选项，避免选中x54导致重复展示；同时用命名向量让用户看到友好标签，后台传递变量名。

2. 动态筛选与标签更新：

   • 通过filter(name %in% c(input$x1, "x54"))实现固定展示x54+动态选择房租变量的逻辑。
   • 用label_map命名向量绑定变量名和对应描述，确保图例标签随选择自动切换。

3. 颜色一致性保障：

   • 用color_map命名向量指定每个变量的颜色，不管选择哪个房租变量，房租柱形颜色统一，月薪柱形颜色固定，避免数据顺序变化导致颜色错乱。

4. 细节调整：

   • 调整position_dodge宽度优化柱形间距；修改X轴文本对齐方式，避免文字重叠。

内容的提问来源于stack exchange，提问作者walter