r - Shiny 的 R 直方图

Question

我正在使用下面的代码来学习 Shiny R ，当我运行此代码时，它给了我这个错误:

Warning: Error in hist.default: 'x' must be numeric [No stack trace available]

library(shiny)

ui <- fluidPage(
  selectInput("Ind","Indipendent Variable",choices = names(mtcars)),
  selectInput('Dep','  Dependent Variable',choices = names(mtcars)),
  plotOutput("BoxPlot"),
  plotOutput('Hist'))

server <- function(input, output, session) {

  data1 <- reactive({input$Ind})
  data2 <- reactive({input$Dep})

  output$BoxPlot <- renderPlot({boxplot(get(data2()) ~ get(data1()) , data=mtcars)})

  output$Hist <- renderPlot({hist(get(data1())}) 

}

shinyApp(ui, server)

任何帮助为什么会这么说？

Answer 1

尽量不要将所有内容都放入一行，因为这不会提高可读性，您可以使用 Google's R Style Guide如果您愿意。要回答您的问题，您可以通过 [[]] 访问变量，如下所示:

library(shiny)

ui <- fluidPage(
  selectInput("Ind","Indipendent Variable",choices = names(mtcars)),
  selectInput('Dep','  Dependent Variable',choices = names(mtcars)),
  plotOutput("BoxPlot"),
  plotOutput('Hist')
)
server <- function(input, output, session) {

  data1 <- reactive({
    input$Ind
  })
  data2 <- reactive({
    input$Dep
  })

  output$BoxPlot <- renderPlot({
    boxplot(get(data2()) ~ get(data1()) , data=mtcars)
  })

  output$Hist <- renderPlot({
    req(data1())
    hist(mtcars[[data1()]])
  }) 

}

shinyApp(ui, server)