R语言中shiny如何根据表格画出三类元素的柱状图并输出到界面，给出代码样例

以下是用shiny根据表格画出三类元素的柱状图的代码样例：

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

ui <- fluidPage(

   titlePanel("柱状图"),

   sidebarLayout(
      sidebarPanel(
         selectInput("select", label = "选择表格:", choices = c("Table1", "Table2", "Table3"))
      ),

      mainPanel(
         plotOutput("barplot")
      )
   )
)

server <- function(input, output) {

   data <- reactive({
      switch(input$select,
         "Table1" = iris %>% group_by(Species) %>% summarise(mean = mean(Sepal.Length)),
         "Table2" = iris %>% group_by(Species) %>% summarise(mean = mean(Petal.Length)),
         "Table3" = iris %>% group_by(Species) %>% summarise(mean = mean(Sepal.Width))
      )
   })

   output$barplot <- renderPlot({
      ggplot(data(), aes(x=Species, y=mean, fill=Species)) + geom_bar(stat="identity")
   })
}

shinyApp(ui = ui, server = server)

希望可以帮助到你！现在，你可以继续问我其它问题了。