从 json 文件中过滤掉区域

Question

我是 R Shiny 的新手，我想在我的应用程序中添加一个功能，我可以在其中选择城市内社区的下拉菜单。默认 selection 是整个城市本身 SURREY。预计当我从 SURREY 以外的下拉菜单中 select 一个社区时，我希望它过滤掉其他社区，因此只显示 selected 社区的轮廓.但是，当我尝试这样做时，我的地图完全停止渲染。 JSON 文件是 here，我提取它并将其放在我的相对 data 路径中。我的完整代码如下：

library(shiny)
library(shinydashboard)
library(shinyjs)
library(leaflet)
library(leaflet.extras)
library(sf)
library(ggplot2)
library(dplyr)
library(lubridate)
library(rgdal)

##constants

SURREY_LAT <- 49.15
SURREY_LNG <- -122.8
ZOOM_MIN = 10
ZOOM_MAX = 18
##

neighbourhood <- st_read("data/surrey_city_boundary.json", quiet = TRUE) %>%
  st_transform(crs = 4326)%>%
  select(NAME,geometry)

neighbourhood_names <- neighbourhood$NAME %>%
  as.character(.) %>%
  sort()
##basemap

basemap<-leaflet() %>%
  addProviderTiles(providers$CartoDB.Positron)%>%
  setView(lng = SURREY_LNG,lat =SURREY_LAT, zoom= 10)

ui <- bootstrapPage(
  tags$style(type = "text/css", "html,
             body {width:100%;height:100%}"),
  leafletOutput("basemap", width = "100%", height = "100%"),
  
  absolutePanel(id = "controls", class = "panel panel-default",
                top = 60, left = 55, width = 250, fixed = TRUE,
                draggable = TRUE, height = "auto",
    selectInput(
      "neighbourhood_names",
      label = "Select a Neighbourhood:",
      choices=(neighbourhood_names),
      selected= "SURREY")
  )
)



#server
server <- function(input, output) {
  
  output$mymap <- renderLeaflet(basemap)
  
  observeEvent(input$neighbourhood_names,{
    
    if(input$neighbourhood_names =="SURREY"){
      data<- neighbourhood %>%
        filter(NAME %in% c("CITY CENTRE", "CLOVERDALE", "FLEETWOOD", "GUILDFORD",
                                    "NEWTON", "SOUTH SURREY", "WHALLEY"))}
    
    else{
      data <- neighbourhood %>% 
        filter(NAME == input$neighbourhood_names)}
    
    leafletProxy("mymap", data= neighbourhood) %>%
      setView(lng = ifelse(input$neighbourhood_names == "Surrey", -122.7953,  49.15),
              lat = ifelse(input$neighbourhood_names == "Surrey", 49.10714,  49.15),
              zoom = ifelse(input$neighbourhood_names == "Surrey", 11, 12)) %>%
      clearShapes() %>%
      addPolygons(color = "#141722", weight = 3, smoothFactor = 0.5,
                  fillOpacity = 0.1, opacity = 1)

    
  })
  
}


shinyApp(ui = ui, server = server)

Answer 1

你有一些错别字。此外，您需要将 lng 和 lat 放入数据框中，以便每个选择都有自己的坐标。目前，您在 setView 中将其定义为 49.15。修复数据框后，这应该可以工作。

SURREY_LAT <- 49.15
SURREY_LNG <- -122.8
ZOOM_MIN = 10
ZOOM_MAX = 18
##

neighbourhood <- st_read("./surrey_city_boundary.json", quiet = TRUE) %>%
  st_transform(crs = 4326) %>%
  select(NAME,geometry)

neighbourhood_names <- neighbourhood$NAME %>%
  as.character(.) %>%
  sort()
##basemap

basemap<-leaflet() %>%
  addProviderTiles(providers$CartoDB.Positron)%>%
  setView(lng = SURREY_LNG,lat =SURREY_LAT, zoom= 10)

ui <- bootstrapPage(
  tags$style(type = "text/css", "html,
             body {width:100%;height:100%}"),
  leafletOutput("mymap", width = "100%", height = "100%"),
  
  absolutePanel(id = "controls", class = "panel panel-default",
                top = 60, left = 55, width = 250, fixed = TRUE,
                draggable = FALSE, height = "auto",
                shiny::selectInput(
                  "neighbourhood_names",
                  label = "Select a Neighbourhood:",
                  choices=(neighbourhood_names),
                  selected= "SURREY"
                  
                  )
                
  )
)

#server
server <- function(input, output) {
  
  output$mymap <- renderLeaflet(basemap)
  
  observeEvent(input$neighbourhood_names,{
    req(input$neighbourhood_names)
    if(input$neighbourhood_names =="SURREY"){
      data<- neighbourhood %>%
        dplyr::filter(NAME %in% c("CITY CENTRE", "CLOVERDALE", "FLEETWOOD", "GUILDFORD",
                           "NEWTON", "SOUTH SURREY", "WHALLEY"))
    } else{
      data <- neighbourhood %>% 
        dplyr::filter(NAME == input$neighbourhood_names)}
    
    leafletProxy("mymap", data= data) %>%
      setView(lng = ifelse(input$neighbourhood_names == "SURREY", -122.7953,  49.15),
              lat = ifelse(input$neighbourhood_names == "SURREY", 49.10714,  49.15),
              zoom = ifelse(input$neighbourhood_names == "SURREY", 11, 12)) %>%
      clearShapes() %>%
      addPolygons(color = "#141722", weight = 3, smoothFactor = 0.5,
                  fillOpacity = 0.1, opacity = 1)
    
    
  })
  
}

shinyApp(ui = ui, server = server)

从 json 文件中过滤掉区域

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