如何添加删除输入行的按钮？

Question

我有一些代码来编写一个小型闪亮应用程序，我需要为其添加输入行，如果需要，再次删除它们。我已经知道如何添加输入，但我不知道如何删除它们。

这是我的代码的 MWE。没有输出，因为我无法共享生成输出的代码后面的 excel 表。但是，只需帮助我找到正确的代码以删除具有完整输入的添加行（第一行除外）就足够了：

library(shiny)

GeographyList <- c("Africa","Asia Pacific","Europe","Global", "United States","Latin America & Caribbean")
RegionList <- c("Emerging", 
                "Developed")
ClassList <- c("1",
               "2",
               "3")


# Define UI for app that draws a plot ----
ui <- fluidPage(
  fluidRow(
    mainPanel(
      uiOutput("inputwidgets"),

      actionButton("number", 
                   "Add Row"),

      # Input: Click to update the Output
      actionButton("update", "Update View"),

      # Output: Plot ----
      h4("Allocation"),
      plotOutput("distPlot")
      )
    )
  )


# Define server logic required to call the functions required ----
server <- function(input, output, session) {

  # Get new input by clicking Add Row
  observeEvent(input$number, {
    output$inputwidgets = renderUI({
      input_list <- lapply(1:input$number, function(i) {
        # for each dynamically generated input, give a different name
        fluidRow(
          column(2,
                 selectInput(paste0("Geography", i),
                             label = paste0("Geography", i),
                             choices = GeographyList,
                             multiple = FALSE,
                             selected = NA)
          ),
          column(3,
                 selectInput(paste0("Region", i),
                             label = paste0("Region", i),
                             choices = RegionList,
                             multiple = FALSE,
                             selected = NA)
          ),
          column(4,
                 selectInput(paste0("Class", i),
                             label = paste0("Class", i),
                             choices = ClassList,
                             multiple = FALSE,
                             selected = NA)
          ),
          column(3, 

                 # Input: Specify the amount ----
                 numericInput(paste0("amount",i), label="Amount", 0)
          ))
      })
      do.call(tagList, input_list)
    })

  })


  output$distPlot <- renderPlot({
    if (input$update == 0)
      return()

    isolate(input$number)
    isolate(input$amount)
    slices <- c(input$amount1,input$amount2,input$amount3,input$amount4)
    pie(slices)
  })


}

# Create Shiny app ----
shinyApp(ui = ui, server = server)

感谢任何提示，因为我是闪亮的新手！提前致谢。

Answer 1

您可以根据添加按钮和删除按钮触发的 reactiveValue 构建您的 lapply 循环：

1.编辑：根据lapply 行在output$distPlot 中使用sapply

2。编辑：使用现有输入值

library(shiny)

GeographyList <- c("Africa","Asia Pacific","Europe","Global", "United States","Latin America & Caribbean")
RegionList <- c("Emerging",
                "Developed")
ClassList <- c("1",
               "2",
               "3")

# Define UI for app that draws a plot ----
ui <- fluidPage(
    fluidRow(
        mainPanel(
            uiOutput("inputwidgets"),

            actionButton("number",
                         "Add Row"),
            actionButton("delete_number",
                         "Delete Row"),


            # Input: Click to update the Output
            actionButton("update", "Update View"),

            # Output: Plot ----
            h4("Allocation"),
            plotOutput("distPlot")
        )
    )
)


# Define server logic required to call the functions required ----
server <- function(input, output, session) {

    reac <- reactiveValues()

    observeEvent(c(input$number,input$delete_number), {
        # you need to add 1 to not start with 0
        add <- input$number+1
        # restriction for delete_number > number
        delete <- if(input$delete_number > input$number) add else input$delete_number
        calc <- add - delete
        reac$calc <- if(calc > 0) 1:calc else 1
    })
    # Get new input by clicking Add Row
    observe({
        req(reac$calc)
        output$inputwidgets = renderUI({
            input_list <- lapply(reac$calc, function(i) {
                Geography <- input[[paste0("Geography",i)]]
                Region <- input[[paste0("Region",i)]]
                Class <- input[[paste0("Class",i)]]
                amount <- input[[paste0("amount",i)]]

                # for each dynamically generated input, give a different name
                fluidRow(
                    column(2,
                           selectInput(paste0("Geography", i),
                                       label = paste0("Geography", i),
                                       choices = GeographyList,
                                       multiple = FALSE,
                                       selected = if(!is.null(Geography)) Geography
                           )
                    ),
                    column(3,
                           selectInput(paste0("Region", i),
                                       label = paste0("Region", i),
                                       choices = RegionList,
                                       multiple = FALSE,
                                       selected = if(!is.null(Region)) Region
                           )
                    ),
                    column(4,
                           selectInput(paste0("Class", i),
                                       label = paste0("Class", i),
                                       choices = ClassList,
                                       multiple = FALSE,
                                       selected = if(!is.null(Class)) Class
                           )
                    ),
                    column(3,

                           # Input: Specify the amount ----
                           numericInput(
                               paste0("amount",i),
                               label="Amount",
                               value = if(!is.null(amount)) amount else 0
                           )
                    ))
            })
            do.call(tagList, input_list)
        })

    })


    output$distPlot <- renderPlot({
        req(reac$calc, input$update)

        slices <- sapply(reac$calc, function(i) {
            c(input[[paste0("amount",i)]])
        })

        pie(slices)
    })

}

# Create Shiny app ----
shinyApp(ui = ui, server = server)