inst/legacy/examples/geojson/server.R

In rstudio/leaflet: Create Interactive Web Maps with the JavaScript 'Leaflet' Library

library(leaflet)

# Data is from https://github.com/craic/zillow_seattle_neighborhoods.
# This example uses a single Feature, but you could use a FeatureCollection or
# any other GeoJSON object. You can also use a GeoJSON string value instead of a
# structured GeoJSON object like this one.
seattle_geojson <- list(
  type = "Feature",
  geometry = list(type = "MultiPolygon",
    coordinates = list(
      list(
        list(
          c(-122.36075812146,  47.6759920119894),
          c(-122.360781646764, 47.6668890126755),
          c(-122.360782108665,  47.6614990696722),
          c(-122.366199035722, 47.6614990696722),
          c(-122.366199035722,  47.6592874248973),
          c(-122.364582509469, 47.6576254522105),
          c(-122.363887331445,  47.6569107302038),
          c(-122.360865528129, 47.6538418253251),
          c(-122.360866157644,  47.6535254473167),
          c(-122.360866581103, 47.6533126275176),
          c(-122.362526540691,  47.6541872926348),
          c(-122.364442114483, 47.6551892850798),
          c(-122.366077719797,  47.6560733960606),
          c(-122.368818463838, 47.6579742346694),
          c(-122.370115159943,  47.6588730808334),
          c(-122.372295967029, 47.6604350102328),
          c(-122.37381369088,  47.660582362063),
          c(-122.375522972109, 47.6606413027949),
          c(-122.376079703095,  47.6608793094619),
          c(-122.376206315662, 47.6609242364243),
          c(-122.377610811371,  47.6606160735197),
          c(-122.379857378879, 47.6610306942278),
          c(-122.382454873022,  47.6627496239169),
          c(-122.385357955057, 47.6638573778241),
          c(-122.386007328104,  47.6640865692306),
          c(-122.387186331506, 47.6654326177161),
          c(-122.387802656231,  47.6661492860294),
          c(-122.388108244121, 47.6664548739202),
          c(-122.389177800763,  47.6663784774359),
          c(-122.390582858689, 47.6665072251861),
          c(-122.390793942299,  47.6659699214511),
          c(-122.391507906234, 47.6659200946229),
          c(-122.392883050767,  47.6664166747017),
          c(-122.392847210144, 47.6678696739431),
          c(-122.392904778401,  47.6709016021624),
          c(-122.39296705153, 47.6732047491624),
          c(-122.393000803496,  47.6759322346303),
          c(-122.37666945305, 47.6759896300663),
          c(-122.376486363943,  47.6759891899754),
          c(-122.366078869215, 47.6759641734893),
          c(-122.36075812146,  47.6759920119894)
        )
      )
    )
  ),
  properties = list(
    name = "Ballard",
    population = 48000,
    # You can inline styles if you want
    style = list(
      fillColor = "yellow",
      weight = 2,
      color = "#000000"
    )
  ),
  id = "ballard"
)

shinyServer(function(input, output, session) {

  map <- createLeafletMap(session, "map")

  session$onFlushed(once = TRUE, function() {
    map$addGeoJSON(seattle_geojson)
  })


  values <- reactiveValues(selectedFeature = NULL)

  observe({
    evt <- input$map_click
    if (is.null(evt))
      return()

    isolate({
      # An empty part of the map was clicked.
      # Null out the selected feature.
      values$selectedFeature <- NULL
    })
  })

  observe({
    evt <- input$map_geojson_click
    if (is.null(evt))
      return()

    isolate({
      # A GeoJSON feature was clicked. Save its properties
      # to selectedFeature.
      values$selectedFeature <- evt$properties
    })
  })

  output$details <- renderText({
    # Render values$selectedFeature, if it isn't NULL.
    if (is.null(values$selectedFeature))
      return(NULL)

    as.character(tags$div(
      tags$h3(values$selectedFeature$name),
      tags$div(
        "Population:",
        values$selectedFeature$population
      )
    ))
  })
})