Question

我是Shiny的新手并且正在学习它的功能。使用mtcars数据，我试图创建一个图表，其轴将根据用户输入进行更改。当我运行应用程序时，我收到错误告诉我＆＃34; x和y长度不一样＆＃34;，所以看起来＆＃34;数据＆＃34;在plot函数中指定的是没有接收mtcars dataframe列。如果我替换＆＃34;数据＆＃34;与服务器功能中列出的任何列。

shinyUI(navbarPage("My Application",
  tabPanel("Component 1"),
  tabPanel("Component 2"),
  tabPanel("Component 3",
    fluidPage(                      
      fluidRow(       
        column(4,
          "Sidebar",
          helpText("This is my longer help text help text."),
          selectInput("var",
            label = "Choose a variable to display",
            choices = c("mpg", "disp", "hp", "qsec"),
            selected = "A")  
        ),
        column(8,
          #style = "background-color:#4d3a7d;",
          "Main",
          textOutput("selected_var"),
          plotOutput("plot1")
        )
      )
    )
),
  navbarMenu("More",
    tabPanel("Sub-Component A"),
    tabPanel("Sub-Component B"))
))


shinyServer(function(input, output) {

  data <- reactive({
    if("mpg" %in% input$var) return(mtcars$mpg)
    if("disp" %in% input$var) return(mtcars$disp)
    if("hp" %in% input$var) return(mtcars$hp)
    if("qsec" %in% input$var) return(mtcars$qsec)
  })

  output$selected_var <- renderText({
    paste("you have selected", input$var)
  }) 

  output$plot1 <- renderPlot({
    plot(mtcars$wt, data)
  })
})

Answer 1

我想通了 - “数据”应该是“data（）”。

Answer 2

我们也可以使用switch代替if。此外，在selected中的selectInput中，它可能是choices中的一个。不确定定义"A"的位置

library(shiny)

-ui

ui <- navbarPage("My Application",
                   tabPanel("Component 1"),
                   tabPanel("Component 2"),
                   tabPanel("Component 3",
                            fluidPage(                      
                              fluidRow(       
                                column(4,
                                       "Sidebar",
                                       helpText("This is my longer help text help text."),
                                       selectInput("var",
                                                   label = "Choose a variable to display",
                                                   choices = c("mpg", "disp", "hp", "qsec"),
                                                   selected = "mpg")  
                                ),
                                column(8,
                                       #style = "background-color:#4d3a7d;",
                                       "Main",
                                       textOutput("selected_var"),
                                       plotOutput("plot1")
                                )
                              )
                            )
                   ),
                   navbarMenu("More",
                              tabPanel("Sub-Component A"),
                              tabPanel("Sub-Component B"))
)

-server

server <- function(input, output) {

  data <- reactive({
     switch(input$var,
            mpg = mtcars$mpg,
            dist = mtcars$disp,
            hp = mtcars$hp,
            qsec = mtcars$qsec
            )

  })

  output$selected_var <- renderText({
    paste("you have selected", input$var)
  }) 

  output$plot1 <- renderPlot({
    plot(mtcars$wt, data(), xlab = "wt", ylab = input$var)
  })
}
shinyApp(ui = ui, server = server)

-output

如何根据用户输入改变绘图轴（闪亮）

2 个答案: