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POGoogle Maps from JSON File
 

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    <p>I'm trying to create a heatmap map with 2 layers using google maps API and heatmaps.js. I'm able to create my map by hard-coding my lat/lon variables, but ultimately I'd like to have my layers fed from JSON files that can easily be refreshed.</p> <p>Here is my current HTML, which works great.</p> <pre><code>&lt;!DOCTYPE html&gt; &lt;html lang="en"&gt; &lt;head&gt; &lt;meta charset="utf-8"&gt; &lt;meta name="viewport" content="width=device-width, initial-scale=1.0"&gt; &lt;meta name="description" content=""&gt; &lt;meta name="author" content=""&gt; &lt;link href='css/bootstrap.css' rel='stylesheet' type='text/css'&gt;&lt;/link&gt; &lt;link href='css/bootstrap-responsive.css' rel='stylesheet' type='text/css'&gt;&lt;/link&gt; &lt;script type='text/javascript' src='http://code.jquery.com/jquery-1.8.3.js'&gt;&lt;/script&gt; &lt;script type='text/javascript' src="https://maps.googleapis.com/maps/api/js?v=3.exp&amp;sensor=false&amp;libraries=visualization&amp;.js"&gt;&lt;/script&gt; &lt;style type="text/css"&gt; body { padding-top: 60px; padding-bottom: 40px; } .sidebar-nav { padding: 9px 0; } @media (max-width: 980px) { /* Enable use of floated navbar text */ .navbar-text.pull-right { float: none; padding-left: 5px; padding-right: 5px; } } &lt;/style&gt; &lt;script&gt; var map, pointarray, heatmap; var layer1 = [ {location: new google.maps.LatLng(42.071523,-72.624257), weight:13.747727085}, {location: new google.maps.LatLng(42.37686,-72.46914), weight:6.6332495807}, {location: new google.maps.LatLng(42.40524,-72.528427), weight:5.1961524227}, {location: new google.maps.LatLng(42.383945,-72.511834), weight:1.7320508076}, {location: new google.maps.LatLng(42.433317,-72.114488), weight:5.6568542495} ]; var layer2 = [ {location: new google.maps.LatLng(41.513113,-74.37616), weight:2.4494897428}, {location: new google.maps.LatLng(41.147711,-73.941171), weight:10}, {location: new google.maps.LatLng(41.329376,-74.347207), weight:4.8989794856}, {location: new google.maps.LatLng(41.338977,-73.987248), weight:1.7320508076} ]; function initialize() { var mapOptions = { zoom: 4, center: new google.maps.LatLng(38.82, -99.408660), mapTypeId: google.maps.MapTypeId.ROADMAP }; map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions); pointArray1 = new google.maps.MVCArray(layer1); pointArray2 = new google.maps.MVCArray(layer2); heatmap1 = new google.maps.visualization.HeatmapLayer({ data: pointArray1 }); heatmap2 = new google.maps.visualization.HeatmapLayer({ data: pointArray2 }); heatmap1.setMap(map); heatmap2.setMap(map); } //FUNCTION TO CHANGE LAYERS function changeMap(layerNum) { if (layerNum == 1) { updateMap(heatmap1); } if (layerNum == 2) { updateMap(heatmap2); } } //FUNCTION TO UPDATE LAYERS function updateMap(layer) { var layerMap = layer.getMap(); if (layerMap) { layer.setMap(null); } else { layer.setMap(map); } } &lt;/script&gt; &lt;link href='css/DT_bootstrap.css' rel='stylesheet' type='text/css'&gt;&lt;/link&gt; &lt;!-- HTML5 shim, for IE6-8 support of HTML5 elements --&gt; &lt;!--[if lt IE 9]&gt; &lt;script src="../assets/js/html5shiv.js"&gt;&lt;/script&gt; &lt;![endif]--&gt; &lt;/head&gt; &lt;body&gt; &lt;div class="navbar navbar-inverse navbar-fixed-top"&gt; &lt;div class="navbar-inner"&gt; &lt;div class="container-fluid"&gt; &lt;button type="button" class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse"&gt; &lt;span class="icon-bar"&gt;&lt;/span&gt; &lt;span class="icon-bar"&gt;&lt;/span&gt; &lt;span class="icon-bar"&gt;&lt;/span&gt; &lt;/button&gt; &lt;a class="brand" href="#"&gt;Test Page&lt;/a&gt; &lt;div class="nav-collapse collapse"&gt; &lt;p class="navbar-text pull-right"&gt; Logged in as &lt;a href="#" class="navbar-link"&gt;...&lt;/a&gt; &lt;/p&gt; &lt;ul class="nav"&gt; &lt;li class="active"&gt;&lt;a href="index.html"&gt;Home&lt;/a&gt;&lt;/li&gt; &lt;li&gt;&lt;a href="#about"&gt;About&lt;/a&gt;&lt;/li&gt; &lt;li&gt;&lt;a href="#contact"&gt;Contact&lt;/a&gt;&lt;/li&gt; &lt;/ul&gt; &lt;/div&gt;&lt;!--/.nav-collapse --&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;body class="container-fluid"&gt; &lt;div class="row"&gt; &lt;div class="span12" style="float: none; margin: 0 auto;"&gt; &lt;body onload="initialize()"&gt; &lt;h3&gt;Test Layers&lt;/h3&gt; &lt;input type='checkbox' name='system_type17' value='1' onclick="changeMap(this.value);" checked="checked" /&gt; &lt;span style="width:100px;display:inline-block;"&gt;Layer 1&lt;/span&gt; &lt;input type="checkbox" name="system_type3" value="2" onclick="changeMap(this.value);" checked="checked" /&gt; &lt;span style="width:100px;display:inline-block;"&gt;Layer 2&lt;/span&gt; &lt;br&gt;&lt;br/&gt; &lt;div id="map-canvas" style="height: 575px; width: 1000px;"&gt;&lt;/div&gt; &lt;/body&gt; &lt;/div&gt; &lt;/div&gt; &lt;/body&gt; &lt;/body&gt; &lt;/html&gt; </code></pre> <p>What I would like to do is replace var layer1 and layer2 with a single JSON file that I would be able to just query, I'm just unsure how to execute something like this. For example, a JSON file that would look something like this:</p> <pre><code>{ "datapoints": [ { "lat": "38.1513366000", "lon": "-97.4341659000", "weight": "0", "layer":"1" }, { "lat": "38.1513748000", "lon": "-97.4341125000", "weight": "0", "layer":"1" }, { "lat": "38.1513938000", "lon": "-97.4341125000", "weight": "0", "layer":"1" }, { "lat": "38.1493263000", "lon": "-97.4339447000", "weight": "0", "layer":"1" }, { "lat": "38.1493339000", "lon": "-97.4339447000", "weight": "0", "layer":"2" }, { "lat": "38.1493377000", "lon": "-97.4339447000", "weight": "0", "layer":"2" }, { "lat": "38.1483650000", "lon": "-97.4358291000", "weight": "0", "layer":"2" }, { "lat": "38.1484031000", "lon": "-97.4358062000", "weight": "0", "layer":"2" } ] } </code></pre> <p>Updated code per Yehia's suggestions:</p> <pre><code>&lt;!DOCTYPE html&gt; &lt;html lang="en"&gt; &lt;head&gt; &lt;meta charset="utf-8"&gt; &lt;meta name="viewport" content="width=device-width, initial-scale=1.0"&gt; &lt;meta name="description" content=""&gt; &lt;meta name="author" content=""&gt; &lt;link href='css/bootstrap.css' rel='stylesheet' type='text/css'&gt;&lt;/link&gt; &lt;link href='css/bootstrap-responsive.css' rel='stylesheet' type='text/css'&gt;&lt;/link&gt; &lt;script type='text/javascript' src='js/jquery-1.8.3.js'&gt;&lt;/script&gt; &lt;script type='text/javascript' src="https://maps.googleapis.com/maps/api/js?v=3.exp&amp;sensor=false&amp;libraries=visualization&amp;.js"&gt;&lt;/script&gt; &lt;style type="text/css"&gt; body { padding-top: 60px; padding-bottom: 40px; } .sidebar-nav { padding: 9px 0; } @media (max-width: 980px) { /* Enable use of floated navbar text */ .navbar-text.pull-right { float: none; padding-left: 5px; padding-right: 5px; } } &lt;/style&gt; &lt;script&gt; var map, pointarray, heatmap; /*var layer1 = [ {location: new google.maps.LatLng(42.071523,-72.624257), weight:13.747727085}, {location: new google.maps.LatLng(42.37686,-72.46914), weight:6.6332495807}, {location: new google.maps.LatLng(42.40524,-72.528427), weight:5.1961524227}, {location: new google.maps.LatLng(42.383945,-72.511834), weight:1.7320508076}, {location: new google.maps.LatLng(42.433317,-72.114488), weight:5.6568542495} ]; var layer2 = [ {location: new google.maps.LatLng(41.513113,-74.37616), weight:2.4494897428}, {location: new google.maps.LatLng(41.147711,-73.941171), weight:10}, {location: new google.maps.LatLng(41.329376,-74.347207), weight:4.8989794856}, {location: new google.maps.LatLng(41.338977,-73.987248), weight:1.7320508076} ];*/ function initialize() { var mapOptions = { zoom: 4, center: new google.maps.LatLng(38.82, -99.408660), mapTypeId: google.maps.MapTypeId.ROADMAP }; map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions); } //FUNCTION TO CHANGE LAYERS function changeMap(layerNum) { if (layerNum == 1) { updateMap(heatmap1); } if (layerNum == 2) { updateMap(heatmap2); } } //FUNCTION TO UPDATE LAYERS function updateMap(layer) { var layerMap = layer.getMap(); if (layerMap) { layer.setMap(null); } else { layer.setMap(map); } } &lt;/script&gt; &lt;link href='css/DT_bootstrap.css' rel='stylesheet' type='text/css'&gt;&lt;/link&gt; &lt;!-- HTML5 shim, for IE6-8 support of HTML5 elements --&gt; &lt;!--[if lt IE 9]&gt; &lt;script src="../assets/js/html5shiv.js"&gt;&lt;/script&gt; &lt;![endif]--&gt; &lt;/head&gt; &lt;body&gt; &lt;div class="navbar navbar-inverse navbar-fixed-top"&gt; &lt;div class="navbar-inner"&gt; &lt;div class="container-fluid"&gt; &lt;button type="button" class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse"&gt; &lt;span class="icon-bar"&gt;&lt;/span&gt; &lt;span class="icon-bar"&gt;&lt;/span&gt; &lt;span class="icon-bar"&gt;&lt;/span&gt; &lt;/button&gt; &lt;a class="brand" href="#"&gt;Test Page&lt;/a&gt; &lt;div class="nav-collapse collapse"&gt; &lt;p class="navbar-text pull-right"&gt; Logged in as &lt;a href="#" class="navbar-link"&gt;...&lt;/a&gt; &lt;/p&gt; &lt;ul class="nav"&gt; &lt;li class="active"&gt;&lt;a href="index.html"&gt;Home&lt;/a&gt;&lt;/li&gt; &lt;li&gt;&lt;a href="#about"&gt;About&lt;/a&gt;&lt;/li&gt; &lt;li&gt;&lt;a href="#contact"&gt;Contact&lt;/a&gt;&lt;/li&gt; &lt;/ul&gt; &lt;/div&gt;&lt;!--/.nav-collapse --&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;body class="container-fluid"&gt; &lt;div class="row"&gt; &lt;div class="span12" style="float: none; margin: 0 auto;"&gt; &lt;body onload="initialize()"&gt; &lt;h3&gt;Test Layers&lt;/h3&gt; &lt;input type='checkbox' name='system_type17' value='1' onclick="changeMap(this.value);" checked="checked" /&gt; &lt;span style="width:100px;display:inline-block;"&gt;Layer 1&lt;/span&gt; &lt;input type="checkbox" name="system_type3" value="2" onclick="changeMap(this.value);" checked="checked" /&gt; &lt;span style="width:100px;display:inline-block;"&gt;Layer 2&lt;/span&gt; &lt;br&gt;&lt;br/&gt; &lt;div id="map-canvas" style="height: 575px; width: 1000px;"&gt;&lt;/div&gt; &lt;/body&gt; &lt;/div&gt; &lt;/div&gt; &lt;script type="text/javascript"&gt; $.getJSON("testdata.json").then(function(data) { $.each(data, function(i,datapoints) { $.each(datapoints, function(j,datapoint) { layers.push({ location: new google.maps.LatLng(datapoint.lat, datapoint.lng), weight: datapoint.weight, layerID: datapoint.layer }); }); }); }); &lt;script&gt; &lt;/body&gt; &lt;/body&gt; &lt;/html&gt; </code></pre> <p>Alright, almost there I think. Thanks so much for your help so far, I know this is painful. Here is my initialize function, I'm still getting Uncaught ReferenceError: layers is not defined </p> <pre><code>&lt;script type='text/javascript'&gt; var map, pointarray, heatmap; function initialize() { function loadData() { var layers = [ ]; $.ajax({ url: 'testdata.json', async: false, dataType: 'json', success: function (data) { for (var i=0; i&lt;data.datapoints.length; i++) { var datapoint = data.datapoints[i]; if (layers[datapoint.layer]===undefined) { layers[datapoint.layer] = []; } layers[datapoint.layer].push({ location: new google.maps.LatLng(datapoint.lat, datapoint.lon), weight: datapoint.weight, layerID: datapoint.layer }); } } }); return layers; } var mapOptions = { zoom: 4, center: new google.maps.LatLng(38.82, -99.408660), mapTypeId: google.maps.MapTypeId.ROADMAP }; map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions); pointArray1 = new google.maps.MVCArray(layers[1]); pointArray2 = new google.maps.MVCArray(layers[2]); heatmap1 = new google.maps.visualization.HeatmapLayer({ data: pointArray1 }); heatmap2 = new google.maps.visualization.HeatmapLayer({ data: pointArray2 }); heatmap1.setMap(map); heatmap2.setMap(map); } //FUNCTION TO CHANGE LAYERS function changeMap(layerNum) { if (layerNum == 1) { updateMap(heatmap1); } if (layerNum == 2) { updateMap(heatmap2); } } //FUNCTION TO UPDATE LAYERS function updateMap(layer) { var layerMap = layer.getMap(); if (layerMap) { layer.setMap(null); } else { layer.setMap(map); } } &lt;/script&gt; </code></pre>
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