D3 Examples - topojson on a map: setup-gl

topojson on a map: setup-gl
This is a simple setup of Leaflet (via Mapbox) with d3 to show dots on a map. This can serve as a base for many interesting geographically based visualizations
Nice overview of using d3 + Leaflet. I found this slightly simpler to use than Mike's classic post.
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<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
  <script src="//d3js.org/topojson.v1.min.js"></script>
  
  <script src='https://api.tiles.mapbox.com/mapbox-gl-js/v0.12.0/mapbox-gl.js'></script>
  <link href='https://api.tiles.mapbox.com/mapbox-gl-js/v0.12.0/mapbox-gl.css' rel='stylesheet' />
​
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
    #map { 
      position:absolute; 
      width: 100%;
      height: 100%;
    }
    svg {
      position: absolute;
      width: 100%;
      height: 100%;
    }
    .land {
      stroke: #111;
      fill: #0a7f7d;
      fill-opacity: 0.2;
    }
  </style>
</head>
​
<body>
  <div id="map"></div>
  <svg id="overlay2"></svg>
  <script>
  
    mapboxgl.accessToken = 'pk.eyJ1IjoiZW5qYWxvdCIsImEiOiJjaWhtdmxhNTIwb25zdHBsejk0NGdhODJhIn0.2-F2hS_oTZenAWc0BMf_uw'
    
    //Setup mapbox-gl map
    var map = new mapboxgl.Map({
      container: 'map', // container id
      style: 'mapbox://styles/enjalot/cihmvv7kg004v91kn22zjptsc',
      center: [-0.1,51.5119112],
      zoom: 11.5,
      
    })
    map.scrollZoom.disable()
    map.addControl(new mapboxgl.Navigation());
​
    // Setup our svg layer that we can manipulate with d3
    var container = map.getCanvasContainer()
    var svg = d3.select(container).append("svg")
​
    
    function project(d) {
      return map.project(getLL(d));
    }
    function getLL(d) {
      return new mapboxgl.LngLat(+d.lon, +d.lat)
    }
    
    var path = d3.geo.path()
    .projection(function(lonlat, i) {
      var p = map.project(new mapboxgl.LngLat(lonlat[0], lonlat[1]))
      return [p.x, p.y];
​
    })
    
    var projection = d3.geo.mercator()
    var path2 = d3.geo.path()
    .projection(projection)
  
    d3.csv("dots.csv", function(err, data) {
    d3.json("london-neighborhoods.topojson", function(err, london) {
      console.log(london.objects['london-neighborhoods-slim'])
      var land = svg.append("path")
      .datum(topojson.feature(london, london.objects['london-neighborhoods-slim']))
      .attr("class", "land")
      .attr("d", path);
      
      var overlay = svg.append("path")
      .datum(topojson.feature(london, london.objects['london-neighborhoods-slim']))
      .attr("class", "land")
      .attr("d")
      
      //console.log(data[0], getLL(data[0]), project(data[0]))
      var dots = svg.selectAll("circle.dot")
        .data(data)
      
      dots.enter().append("circle").classed("dot", true)
      .attr("r", 1)
      .style({
        fill: "#0082a3",
        "fill-opacity": 0.6,
        stroke: "#004d60",
        "stroke-width": 1
      })
      .transition().duration(1000)
      .attr("r", 6)
      
      function render() {
        dots
        .attr({
          cx: function(d) { 
            var x = project(d).x;
            return x
          },
          cy: function(d) { 
            var y = project(d).y;
            return y
          },
        })
        land.attr("d", path)
      }
​
      // re-render our visualization whenever the view changes
      map.on("viewreset", function() {
        render()
      })
      map.on("move", function() {
        render()
      })
​
      // render our initial visualization
      render()
    }) })
​
    
  </script>
</body>
​
    