Question

我有一个很简单的问题，但无法弄清楚为什么它不起作用

library(shiny)
library(leaflet)


pts <- data.frame(
  id = letters[seq(from = 1, to = 10)],
  x = rnorm(10, mean = -93.625),
  y = rnorm(10, mean = 42.0285),
  stringsAsFactors = F
)




# Define UI
ui <- fluidPage(uiOutput('Select'))

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

  output$Select <- renderUI({
    Range <- sort(unique(pts$id))
    selectInput("dataselect",
                "select",
                choices = Range,
                selected = 'a')
  })


  mydata <- reactive({
    if (input$dataselect != 'a') {
      data <- pts[pts$id == input$dataselect,]
    }
    else
    {
      data <- pts
    }


  })

  observe(print(mydata()))


}


shinyApp(ui = ui, server = server)

如果使用所选值选择了'a'以外的任何内容，我基本上会尝试对我的数据集进行子集化。如果选择'a'，我希望返回整个df。

只需碰上

警告：if：参数长度为零的错误[无堆栈跟踪可用]

Answer 1

如果input $ dataselect不可用，则不需要运行mydata（），可以通过插入以下命令来完成：req（input $ dataselect）

如下所示：



library(shiny)
library(leaflet)


pts <- data.frame(
  id = letters[seq(from = 1, to = 10)],
  x = rnorm(10, mean = -93.625),
  y = rnorm(10, mean = 42.0285),
  stringsAsFactors = F
)




# Define UI
ui <- fluidPage(uiOutput('Select'))

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


  output$Select <- renderUI({
    Range <- sort(unique(pts$id))
    selectInput("dataselect",
                "select",
                choices = Range,
                selected = 'a')
  })


  mydata <- reactive({
    req(input$dataselect)
    if (input$dataselect != 'a') {
      data <- pts[pts$id == input$dataselect,]
    }
    else
    {
      data <- pts
    }


  })

  observe(print(mydata()))


}


shinyApp(ui = ui, server = server)

如果还有闪亮的反应性

1 个答案: