Shiny中如何实现按by字段分组绘图并支持全量数据展示

核心改动只有两处：给分组选择器新增全量数据选项、渲染绘图时按用户选择过滤数据集，调整后代码可直接运行：

核心修改点 #

• 侧边栏下拉选择器新增"全量数据"作为默认选项，保留原有分组值供切换
• 服务端先判断用户选中的范围：选全量时使用完整原始数据，选具体分组时先按by字段筛选匹配子集
• 排序、颜色赋值等数据处理逻辑全部基于过滤后的数据集执行，保证不同视图下样式规则统一

library(shiny)
library(ggplot2)
library(dplyr)

ui <- fluidPage(
  titlePanel("全量/分组切换绘图"),
  sidebarLayout(
    sidebarPanel( 
      width = 2, 
      selectInput(
        inputId = "by", 
        label = "数据范围",
        choices = c("全量数据", "by.1", "by.2"), 
        selected = "全量数据"
      )
    ),
    mainPanel(
      plotOutput("distPlot")
    )
  )
)

server <- function(input, output) {
  output$distPlot <- renderPlot({
    # 原始数据集
    raw_df <- data.frame(
      dose = c("D0.5", "D1", "D2", "D3", "D4", "D5"),
      len = c(4.2, 10, 29.5, 5, 7, 15), 
      by = c("by.1", "by.1","by.1","by.2","by.2","by.2")
    )
    
    mycols <- c("#92d050", "#57d3ff", "#ffc000")
    
    # 按选择过滤绘图数据
    plot_df <- if(input$by == "全量数据") {
      raw_df
    } else {
      raw_df %>% filter(by == input$by)
    }
    
    # 基于过滤后的数据做排序、颜色映射
    plot_df <- plot_df %>%
      arrange(desc(len)) %>%
      mutate(fills = ifelse(row_number() <= length(mycols), mycols, "grey50"))
    
    # 绘图
    ggplot(data = plot_df, aes(x = len, y = reorder(dose, len))) +
      geom_col(aes(fill = I(fills)))+
      geom_text(aes(x = len/2, label = glue::glue("{dose} ({len}%)"))) +
      theme_minimal() +
      scale_x_continuous(NULL, expand = c(0,0)) +
      theme(
        axis.ticks.y = element_blank(), 
        axis.title.y = element_blank(), 
        axis.text.y = element_blank()
      )
  })
}

shinyApp(ui = ui, server = server)

内容的提问来源于stack exchange，提问作者symkly