从 R Shiny 的下拉菜单中选择绘图答案

【问题标题】：Select plot from a dropdown menu in RShiny从 R Shiny 的下拉菜单中选择绘图
【发布时间】：2021-10-02 06:13:56
【问题描述】：

我正在创建一个shiny 应用程序，用户可以在其中选择plot 进行查看。我使用this question 作为一种方法，但我收到了一个错误。我该如何解决这个问题？

用户界面

library(shiny)
library(shinydashboard)
library(shinythemes) 
library(tidyverse)

ui =   navbarPage("Project ", theme = shinytheme("cyborg")
                  uiOutput("all"),
       tabPanel("Plot",
                      icon = icon("chart-area"),
                      sidebarLayout(sidebarPanel(
                                    selectInput("Plot", "Please select a plot to view:",
                                                 choices = c("Plot-1", "Plot-2")),
                                    submitButton("Submit")),
                      plotOutput(outputId = "Plots",
                                   width = "1024px",
                               height = "768px")
              )))

服务器

server = function(input, output, session) {

data = eventReactive(input$Plot,{
            switch(input$Plot,
                   "Plot-1" = Plot1,
                   "Plot-1" = Plot2)
        })

output$Plots = renderPlot({

             data("midwest", package = "ggplot2") # Sample data

              Plot1 = ggplot(midwest, aes(x=area, y=poptotal)) +
                      geom_point()
              Plot2 =  ggplot(midwest, aes(x=area, y=poptotal)) + geom_point() + 
                       geom_smooth(method="lm")
 
        })
        

}

# Run the application 
shinyApp(ui = ui, server = server)

错误

【问题讨论】：

标签： r shiny

【解决方案1】：

这是一种方法-

library(shiny)
library(shinydashboard)
library(shinythemes)

ui =   navbarPage("Project ", theme = shinytheme("cyborg"),
                  uiOutput("all"),
                  tabPanel("Plot",
                           icon = icon("chart-area"),
                           sidebarLayout(sidebarPanel(
                             selectInput("Plot", "Please select a plot to view:",
                                         choices = c("Plot-1", "Plot-2")),
                             actionButton("submit", "Submit")),
                             plotOutput(outputId = "Plots",
                                        width = "1024px",
                                        height = "768px")
                           )))

server = function(input, output, session) {
  
  observeEvent(input$submit,{

      Plot1 = ggplot(midwest, aes(x=area, y=poptotal)) +
        geom_point()
      Plot2 =  ggplot(midwest, aes(x=area, y=poptotal)) + geom_point() + 
        geom_smooth(method="lm")

  output$Plots = renderPlot({
    switch(isolate(input$Plot),
           "Plot-1" = Plot1,
           "Plot-2" = Plot2)
  })
  
  })
  

  
  
}

# Run the application 
shinyApp(ui = ui, server = server)

【讨论】：

在switch语句中调用ggplot不是更高效吗？这样，当只需要返回其中一个时，两个图都被构建。
是的，我认为你是对的，这样会更有效率。