D3 Examples - Mapping LA Part 2

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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://d3js.org/d3.v4.min.js"></script>
  <script src='https://api.mapbox.com/mapbox-gl-js/v0.31.0/mapbox-gl.js'></script>
  <link href='https://api.mapbox.com/mapbox-gl-js/v0.31.0/mapbox-gl.css' rel='stylesheet' />
​
  <style>
    /* apply a natural box layout model to all elements, but allowing components to change */
    html {
      box-sizing: border-box;
    }
    *, *:before, *:after {
      box-sizing: inherit;
    }    
    body { 
      margin:0;position:fixed;top:0;right:0;bottom:0;left:0; 
      font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
      color: #1A2D37;
      font-size: 12px;
    }
    #map { 
      position:absolute; 
      width: 100%;
      height: 100%;
    }
    canvas {
      position: absolute;
      width: 100%;
      height: 100%;
    }
    #property-card {
      position: fixed;
      height: 400px;
      width: 300px;
      top: 8px;
      left: 8px;
      border-radius: 4px;
      background-color: #F2F2F4;
      overflow: scroll;
    }
    .section {
     background-color: #FFFFFF; 
     border-radius: 4px;
     margin: 8px;
     padding: 5px;
    }
  </style>
</head>
​
<body>
  <div id="map"></div>
  <div id="property-card"></div>
  <script>
    function buildUrl(url, queryParams) {
      url += '?';
      queryParams.forEach(function(param){
        url += `${param}&`
      })
      return url.slice(0, -1);
    }
  </script>
​
  <script>
    //Setup mapbox-gl map
    mapboxgl.accessToken = 'pk.eyJ1Ijoiam9uc2Fka2EiLCJhIjoiY2l4ejkzM3FuMDA0bzMycDl2ZXE0cGw2byJ9.YVf_mtIw3xABynhjwojKQg';
    const map = new mapboxgl.Map({
      center: [-118.4, 34],
      container: 'map', // id of the container
      pitch: 40,
      scrollZoom: true,
      style: 'mapbox://styles/jonsadka/cixzpqzbj003g2srjakw769o5',
      zoom: 9
    })
    map.addControl(new mapboxgl.NavigationControl())
​
    function project(d) {
      const position = getLatLong(d);
      if (position) {
        return map.project(position);
      }
    }
    function getLatLong(d) {
      const longitude = +d.center_lon || (+d.location_1 || {}).longitude;
      const latitude = +d.center_lat || (+d.location_1 || {}).latitude;
      if (longitude && latitude) {
        return new mapboxgl.LngLat(longitude, latitude);
      }
    }
​
    const container = map.getCanvasContainer();
    const canvas = d3.select(container).append('canvas').node();
    const boundingBox = document.body.getBoundingClientRect();
    canvas.width = boundingBox.width;
    canvas.height = boundingBox.height;
    const context = canvas.getContext('2d');
      
    const url06To16 = 'https://data.lacounty.gov/resource/hvzm-fn38.json';
​
    d3.queue()
        .defer(d3.json, buildUrl(url06To16, [
          '$where=units > 22', '$limit=20000', 'yearbuilt=1989'
        ]))
      .await(initialRender)
​
    let diagram;
​
    function initialRender(error, propertyData) {
      if (error) return console.warn(error);
​
      console.log(
        propertyData.length,
        propertyData[0], 
        getLatLong(propertyData[0]), 
        project(propertyData[0])
      )
      
      propertyData.map(function(property){
        const point = project(property);
        if (point) {
          property.computed = property.computed || {};
          property.computed.x = point.x;
          property.computed.y = point.y;
        }
        return property;
      })
​
      const voronoi = d3.voronoi()
                          .x(function(d){ return d.computed.x})
                          .y(function(d){ return d.computed.y});
      diagram = voronoi(propertyData);
​
      // Initial render
      render(propertyData);
​
      // re-render our visualization whenever the view changes
      map.on('viewreset', function() {
        context.clearRect(0, 0, boundingBox.width, boundingBox.height);
  
        propertyData.map(function(property){
          const point = project(property);
          if (point) {
            property.computed = property.computed || {};
            property.computed.x = point.x;
            property.computed.y = point.y;
          }
          return property;
        })
        diagram = voronoi(propertyData);
        render(propertyData);
      })
      map.on('move', function() {
        context.clearRect(0, 0, boundingBox.width, boundingBox.height);
        propertyData.map(function(property){
          const point = project(property);
          if (point) {
            property.computed = property.computed || {};
            property.computed.x = point.x;
            property.computed.y = point.y;
          }
          return property;
        })
        diagram = voronoi(propertyData);
        render(propertyData);
      })
      
      let lastProperty;
      map.on('mousemove', function(event) {
        const voronoiCell = diagram.find(event.point.x, event.point.y);
        const propertyCard = document.getElementById('property-card');
        
        if (lastProperty !== voronoiCell.data.propertylocation) {
          lastProperty = voronoiCell.data.propertylocation;
​
          var content = document.createElement('div');
          content.innerText = lastProperty;
          content.className = 'section';
          propertyCard.append(content);  
          propertyCard.scrollTop = propertyCard.scrollHeight;      
        }
      })
    }
​
    function render(data) {
      const propertyValues = data.reduce(function(_propertyValues, property){
        if (property.roll_totlandimp) {
          _propertyValues.push(+property.roll_totlandimp);
        }
        return _propertyValues;
      }, []);
​
      const propertyValueColor = d3.scaleLog()
        .range(['hsl(62,100%,90%)', 'hsl(228,30%,20%)'])
        .domain([d3.quantile(propertyValues, .01), d3.quantile(propertyValues, .99)])
        .interpolate(d3.interpolateHcl);
​
      context.clearRect(0, 0, boundingBox.width, boundingBox.height);
​
      data.forEach(function(property, idx) {
        context.strokeStyle = '#F2F2F4';
        if (property.computed) {
          context.fillStyle = propertyValueColor(+property.roll_totlandimp);
          context.beginPath();
          context.arc(property.computed.x, property.computed.y, 4, 0, Math.PI * 2);
          context.fill();
          context.stroke();
        }
      })
    }
  </script>
</body>
    