如何从shapefile传单R访问多边形信息

Posted 2021-04-13

我用https://data.london.gov.uk/dataset/statistical-gis-boundary-files-london和闪亮的R和传单制作了伦敦地图。我在shapefile中添加了一个属性，现在希望能够在用户单击特定多边形时突出显示shapefile并打印信息。

我看了shiny leaflet ploygon click event，Marker mouse click event in R leaflet for shiny和How to implement input$map_marker_click correctly?，知道我需要使用ObserveEvent，但是无法正确实现它。

我的代码是：

library(shiny)
library("rgdal")
library(leaflet)

shapeData <- readOGR('statistical-gis-boundaries-london/ESRI/LSOA_2004_London_Low_Resolution.shp')
shapeData <- spTransform(shapeData, CRS("+proj=longlat +ellps=GRS80"))
shapeData$col=sample(c('red','yellow','green'),nrow(shapeData),1) #add some value you want to map
borough=read.csv('BoroughCentres.csv')

ui=fluidPage(
  fluidPage(
    leafletOutput('LSOAMap'),
    p(),
    selectInput('LANAME','Borough',
                choices = unique(shapeData$LA_NAME))
  )

) 


server=function(input, output) {

  output$LSOAMap <- renderLeaflet({
    llong=borough[borough$Borough==input$LANAME,3]
    llat=borough[borough$Borough==input$LANAME,4]

   bor=subset(shapeData,shapeData$LA_NAME %in% input$LANAME)
    leaflet()  %>% addTiles() %>% 
      setView(lng = llong, lat=llat,zoom=13) %>% 
      addPolygons(data=bor,weight=2,col = 'black',fillOpacity = 0.2,fillColor = bor$col,
                  highlightOptions = highlightOptions(color='white',weight=1,
                                                      bringToFront = TRUE)) %>% 
      addMarkers(lng = llong,lat=llat,popup=input$LANAME) 
  }) 

}
shinyApp(ui, server)

我尝试添加，以及session作为参数：

  observe({
    click <- input$map_marker_click
    if (is.null(click))
      return()

    print(click)
    text <-
      paste("Lattitude ",
            click$lat,
            "Longtitude ",
            click$lng)

    leafletProxy(mapId = "LSOAMap") %>%
      clearPopups() %>%
      addPopups(dat = click, lat = ~lat, lng = ~lng, popup = text)

    # map$clearPopups()
    # map$showPopup(click$latitude, click$longtitude, text)
  })

无济于事。

我想要的是当用户突出显示特定形状时，弹出文本并从shapefile中显示相应的STWARDNAME。

自治市镇的前几行是：

> head(borough)
               Borough   LA_CODE        long      lat
1       City of London E09000001 -0.09194991 51.51814
2 Barking and Dagenham E09000002  0.13064556 51.54764
3               Barnet E09000003 -0.20416711 51.61086
4               Bexley E09000004  0.13459320 51.45981
5                Brent E09000005 -0.26187070 51.55697
6              Bromley E09000006  0.03734663 51.38836

答案

你非常接近，但有一些语法问题，我认为这些问题正在绊倒你。

首先，你没有从你的SPDF中正确选择你想要的STWARDNAME，所以R无法知道要显示哪一个。我添加了这一行

popup = subset(shapeData, LA_NAME == input$LANAME )$STWARDNAME

你也可以通过highlightOptions作为选项，它应该只是highlight

最后，因为您对多边形的鼠标悬停更感兴趣，我删除了弹出标记并更改为highlight，以便在鼠标悬停多边形时显示名称：

leaflet()  %>% addTiles() %>% 
  setView(lng = llong, lat=llat,zoom=13) %>% 
  addPolygons(data=bor,weight=2,col = 'black',fillOpacity = 0.2,fillColor = bor$col,
              highlight = highlightOptions(color='white',weight=1,
                                                  bringToFront = TRUE), label= popup)

产量：

另一答案

@Stedy回答很棒，而且更好，我只是采取了不同的方式。我添加了一个图层id矢量，并弹出一个决定来查找STWARDNAME

lid=as.vector(row.names(bor@data))
pu=bor@data[row.names(bor@data)==lid,'STWARDNAME']

，然后在制作地图layerId = lid,popup = pu,时加入两个参数。当用户点击某个区域时弹出窗口显示

bor=subset(shapeData,shapeData$LA_NAME %in% input$LANAME)
lid=as.vector(row.names(bor@data))
pu=bor@data[row.names(bor@data)==lid,'STWARDNAME']
leaflet()  %>% addTiles() %>% 
  setView(lng = llong, lat=llat,zoom=13) %>% 
  addPolygons(data=bor,weight=2,col = 'black',fillOpacity = 0.2,fillColor = bor$col,
              layerId = lid,popup = pu,
              highlightOptions = highlightOptions(color='white',weight=1,
                                                  bringToFront = TRUE)) %>% 
  addMarkers(lng = llong,lat=llat,popup=input$LANAME)