r语言 - 闪亮 + 传单反应功能不起作用

Question

我的数据由 lon 、lat、region、平面类型和年份等列组成。我使用传单和闪亮来创建带有集群标记的地图。

我包括 2 个选择输入框 - 一个用于年份，一个用于平面类型。使用反应函数，每当我运行闪亮的应用程序时，它都会给我此错误。

错误：不知道如何从类对象获取位置数据 反应式，反应式

这是我的代码

library(shiny)
library(leaflet)
library(dplyr)
ui <- fluidPage(
    titlePanel("Transactions for Resale Flats"),
    h3("Model A Flats: 3-Room, 4-Room, 5-Room"),
    sidebarLayout(position = 'right',
        sidebarPanel(
            selectInput("year","Year", choices = c("2007","2008",
                                                   "2009","2010","2011",
                                                   "2012","2013","2014",
                                                   "2015","2016","2017"), selected="2007"),
            selectInput("type","Flat-Type",choices = c("3 ROOM",'4 ROOM',"5 ROOM"),selected = "3-Room"),
            width = 2),
        mainPanel(leafletOutput("mymap",height = 650,width=605)))

)

server <- function(input,output, session){
    headlinedata<-reactive({
        headlinedata%>%
            filter(year %in% input$year & flat_type %in% input$type)
    })
    output$mymap <- renderLeaflet({
        leaflet(data=headlinedata) %>% 
            addTiles() %>% 
            addMarkers(clusterOptions = markerClusterOptions(),
            label = paste(headlinedata$address,',',headlinedata$town))
          })
    observe(leafletProxy('mymap', data=headlinedata()))%>%
    clearMarkers()%>%
    addMarkers(clusterOptions = markerClusterOptions(),
               label = paste(headlinedata$address,',',headlinedata$town))
}
shinyApp(ui = ui, server = server)

还有这个代码

  observe(leafletProxy('mymap', data=headlinedata()))%>%
        clearMarkers()%>%
        addMarkers(clusterOptions = markerClusterOptions(),
                   label = paste(headlinedata$address,',',headlinedata$town))

每当我包含它时，应用程序将运行一秒钟，然后立即关闭。此代码应该在输入更改时更新地图标记。

谢谢。

Answer 1

首先，您需要将反应变量称为变量名称，后跟 () 。在output$mymap中，你指的是headlinedata，这是要过滤的数据框，当它应该被headlinedata()时，它是已经被过滤的反应变量。为了消除两者的歧义，我将反应变量的名称更改为 df 。然后，当下游代码中需要该反应变量时，我将其称为df()。

其次，由于df()是一个反应变量，并且我们已经设置了依赖于它的传单，因此每当反应变量发生变化时，地图也会发生变化。这意味着我们不需要observe(leafletProxy ...代码。

下面是一个可以复制和粘贴的可重现示例。

library(shiny)
library(leaflet)
library(dplyr)
set.seed(1)
headlinedata <- data.frame(year = rep(2007:2017, 10),
                           flat_type = sample(c("3 ROOM",'4 ROOM',"5 ROOM"),
                                         110, replace=T),
                           lat = sample(1:50,  110, replace=T),
                           lng = sample(1:50, 110, replace=T),
                           address = "address", 
                           town = "town")
ui <- fluidPage(
    titlePanel("Transactions for Resale Flats"),
    h3("Model A Flats: 3-Room, 4-Room, 5-Room"),
    sidebarLayout(position = 'right',
                  sidebarPanel(
                      selectInput("year","Year", choices = c("2007","2008",
                                                             "2009","2010","2011",
                                                             "2012","2013","2014",
                                                             "2015","2016","2017"), selected="2007"),
                      selectInput("type","Flat-Type",choices = c("3 ROOM",'4 ROOM',"5 ROOM"),selected = "3-Room"),
                      width = 2),
                  mainPanel(leafletOutput("mymap",height = 650,width=605)))

)

server <- function(input,output, session){
    df<-reactive({
        headlinedata%>%
            dplyr::filter(year %in% input$year & flat_type %in% input$type)
    })
    output$mymap <- renderLeaflet({
        leaflet(data=df()) %>% 
            addTiles() %>% 
            addMarkers(clusterOptions = markerClusterOptions(),
                       label = paste(df()$address,',',df()$town))
    })

}
shinyApp(ui = ui, server = server)