Question

如何在不使用全局变量的情况下实现与以下示例相同的功能。我怀疑答案可能与'reactiveValues（）'函数有关，但我不能让它起作用。

library(shiny)
library(DT)

ui <- fluidPage(
  selectInput("selectMe", "Select Something", list(A="A",B="B",C="C",D="D",E="E")),
  actionButton("pressMe", "Add Something"),
  DT::dataTableOutput("theTable")
)

someThings <<- isolate(data.frame())

renderTable = function(input) {
  DT::renderDataTable({
    currentSelect = isolate(input$selectMe)
    if (input$pressMe > 0) {
      currentThings = someThings
      newThings = rbind(currentThings, data.frame(SelectedThing = currentSelect))
      someThings <<- isolate(newThings)
      newThings
    }
  })
}

server <- function(input, output, session) {
  output$theTable = renderTable(input)
}

shinyApp(ui, server)

Answer 1

您对reactiveValues的建议很好，但由于我们只想保留一个变量（data.frame），我们也可以使用reactiveVal。我们旁边要求的只是一个observeEvent，它会监听按钮点击。工作示例：

library(shiny)
library(DT)

ui <- fluidPage(
  selectInput("selectMe", "Select Something", list(A="A",B="B",C="C",D="D",E="E")),
  actionButton("pressMe", "Add Something"),
  DT::dataTableOutput("theTable")
)

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

  my_df <- reactiveVal(data.frame())

  observeEvent(input$pressMe,ignoreNULL = T,ignoreInit = T, {
    currentThings = my_df()
    newThings = rbind(currentThings, data.frame(SelectedThing = input$selectMe))
    my_df(newThings) # set the new value of the reactiveVal.
  })

  output$theTable = renderDataTable(my_df())
}

shinyApp(ui, server)

希望这有帮助！

R Shiny - 如何在不使用全局变量的情况下动态添加到表中？

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