Question

我试图创建一个闪亮的应用程序，使用gvisGeoMap绘制美国或世界的地图。这就是我现在所拥有的：

# server.R
library(googleVis)
library(shiny)
shinyServer(function(input, output) {
  if(input$dataset=="World"){
    df = readRDS("./DATA/countries.RDS")
    output$view <- renderGvis({
      gvisGeoMap(df, locationvar="country", numvar="count",
                 options=list(dataMode="regions"))
    })
  }else{
    df = readRDS("./DATA/USA.RDS")
    output$view <- renderGvis({
      gvisGeoMap(df,  locationvar="metro_code", numvar="count",
                 options=list(dataMode="regions", region="us_metro"))
    })
  }
})

和我的ui.R

# ui.R
shinyUI(pageWithSidebar(
  headerPanel("Geolocation"),
  sidebarPanel(
    selectInput("dataset", "Choose a map:", 
                choices = c("World", "USA"))
  ),
  mainPanel(
    htmlOutput("view")
  )
))

当我尝试运行应用时出现此错误

Error in .getReactiveEnvironment()$currentContext() : 
  Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)

我认为我需要用反应函数包装我的代码，但我不确定如何。

感谢您的帮助

Answer 1

您需要将被动回应包裹在observer

中

library(googleVis)
library(shiny)
runApp(
  list(server = function(input, output) {
    observe({
      if(input$dataset=="World"){
        df = readRDS("./DATA/countries.RDS")
        output$view <- renderGvis({
          gvisGeoMap(df, locationvar="country", numvar="count",
                   options=list(dataMode="regions"))
        })
      }else{
        df = readRDS("./DATA/USA.RDS")
        output$view <- renderGvis({
          gvisGeoMap(df,  locationvar="metro_code", numvar="count",
                   options=list(dataMode="regions", region="us_metro"))
        })
      }
    })
  }
  , ui = pageWithSidebar(
    headerPanel("Geolocation"),
    sidebarPanel(
      selectInput("dataset", "Choose a map:", 
                  choices = c("World", "USA"))
    ),
    mainPanel(
      htmlOutput("view")
    )
  )
)
)

有光泽和gvisGeoMap中的反应数据

1 个答案: