Heatmaps

by Diana Lemen

HTML

<div id="floating-panel">
  <button onclick="toggleHeatmap()">Toggle Heatmap</button>
  <button onclick="changeGradient()">Change gradient</button>
  <button onclick="changeRadius()">Change radius</button>
  <button onclick="changeOpacity()">Change opacity</button>
</div>
<div id="map"></div>
<!-- Replace the value of the key parameter with your own API key. -->
<script async defer
        src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&libraries=visualization&callback=initMap">
    </script>

CSS

/* Always set the map height explicitly to define the size of the div
 * element that contains the map. */
#map {
  height: 100%;
}
/* Optional: Makes the sample page fill the window. */
html, body {
  height: 100%;
  margin: 0;
  padding: 0;
}
#floating-panel {
  position: absolute;
  top: 10px;
  left: 25%;
  z-index: 5;
  background-color: #fff;
  padding: 5px;
  border: 1px solid #999;
  text-align: center;
  font-family: 'Roboto','sans-serif';
  line-height: 30px;
  padding-left: 10px;
}
#floating-panel {
  background-color: #fff;
  border: 1px solid #999;
  left: 25%;
  padding: 5px;
  position: absolute;
  top: 10px;
  z-index: 5;
}

JavaScript

// This example requires the Visualization library. Include the libraries=visualization
// parameter when you first load the API. For example:
// <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=visualization">

var map, heatmap;

function initMap() {
  map = new google.maps.Map(document.getElementById('map'), {
    zoom: 13,
    center: {lat: 37.775, lng: -122.434},
    mapTypeId: 'satellite'
  });

  heatmap = new google.maps.visualization.HeatmapLayer({
    data: getPoints1(),
    map: map
  });
  
  heatmap = new google.maps.visualization.HeatmapLayer({
    data: getPoints(),
    map: map
  });
}

function toggleHeatmap() {
 heatmap.setMap(null);
 heatmap.setMap(null);
}

function changeGradient() {
  var gradient = [
    'rgba(0, 255, 255, 0)',
    'rgba(0, 255, 255, 1)',
    'rgba(0, 191, 255, 1)',
    'rgba(0, 127, 255, 1)',
    'rgba(0, 63, 255, 1)',
    'rgba(0, 0, 255, 1)',
    'rgba(0, 0, 223, 1)',
    'rgba(0, 0, 191, 1)',
    'rgba(0, 0, 159, 1)',
    'rgba(0, 0, 127, 1)',
    'rgba(63, 0, 91, 1)',
    'rgba(127, 0, 63, 1)',
    'rgba(191, 0, 31, 1)',
    'rgba(255, 0, 0, 1)'
  ]
  heatmap.set('gradient', heatmap.get('gradient') ? null : gradient);
}

function changeRadius() {
  heatmap.set('radius', heatmap.get('radius') ? null : 20);
}

function changeOpacity() {
  heatmap.set('opacity', heatmap.get('opacity') ? null : 0.2);
}

// Heatmap data: 500 Points

function getPoints1() {
  return [ 
  	new google.maps.LatLng(37.782551, -122.445368),
    new google.maps.LatLng(37.782745, -122.444586),
    new google.maps.LatLng(37.782842, -122.443688),
    new google.maps.LatLng(37.782919, -122.442815),
    new google.maps.LatLng(37.782992, -122.442112),
    new google.maps.LatLng(37.783100, -122.441461)
    ]
}


function getPoints() {
  return [
    new google.maps.LatLng(37.782551, -122.445368),
    new google.maps.LatLng(37.782745, -122.444586),
    new google.maps.LatLng(37.782842, -122.443688),
    new...