Google Maps marker grouping

There are various ways to tackle this, but let me show you one approach.

First, let's start with an array of locations (borrowed from the Google Maps API Tutorials):

var beaches = [
  ['Bondi Beach', -33.890542, 151.274856, 1],
  ['Coogee Beach', -33.923036, 151.259052, 1],
  ['Cronulla Beach', -34.028249, 151.157507, 2],
  ['Manly Beach', -33.800101, 151.287478, 2],
  ['Maroubra Beach', -33.950198, 151.259302, 2]
];

This is actually an array of arrays. It represents 5 Australian beaches, and we have the name, latitude, longitude and category. The category in this case is just a number for the sake of simplicity.

Then it is important that we keep a reference of the markers that we create. To do this, we can use a markers array where we store each new marker, and we can also augment each marker object with its category id:

var markers = [];

var i, newMarker;

for (i = 0; i < beaches.length; i++) {
  newMarker = new google.maps.Marker({
    position: new google.maps.LatLng(beaches[i][1], beaches[i][2]),
    map: map,
    title: beaches[i][0]
  });     

  newMarker.category = beaches[i][3];     
  newMarker.setVisible(false);

  markers.push(newMarker);
}

Finally, when we need to show the markers, we can simply iterate over the markers array, and call the setVisible() method according to what category we would like to show.

You may want to check out the following complete example:

<!DOCTYPE html>
<html> 
<head> 
   <meta http-equiv="content-type" content="text/html; charset=UTF-8"/> 
   <title>Google Maps JavaScript API v3 Example: Marker Categories</title> 
   <script type="text/javascript" 
           src="http://maps.google.com/maps/api/js?sensor=false"></script>
</head> 
<body> 
   <div id="map" style="width: 400px; height: 300px;"></div> 

   <input type="button" value="Show Group 1" onclick="displayMarkers(1);">
   <input type="button" value="Show Group 2" onclick="displayMarkers(2);">

   <script type="text/javascript"> 

   var beaches = [
     ['Bondi Beach', -33.890542, 151.274856, 1],
     ['Coogee Beach', -33.923036, 151.259052, 1],
     ['Cronulla Beach', -34.028249, 151.157507, 2],
     ['Manly Beach', -33.800101, 151.287478, 2],
     ['Maroubra Beach', -33.950198, 151.259302, 2]
   ];

   var map = new google.maps.Map(document.getElementById('map'), {
      zoom: 10,
      center: new google.maps.LatLng(-33.88, 151.28),
      mapTypeId: google.maps.MapTypeId.ROADMAP
   });

   var markers = [];

   var i, newMarker;

   for (i = 0; i < beaches.length; i++) {
     newMarker = new google.maps.Marker({
       position: new google.maps.LatLng(beaches[i][1], beaches[i][2]),
       map: map,
       title: beaches[i][0]
     });

     newMarker.category = beaches[i][3];
     newMarker.setVisible(false);

     markers.push(newMarker);
   }

   function displayMarkers(category) {
     var i;

     for (i = 0; i < markers.length; i++) {
       if (markers[i].category === category) {
         markers[i].setVisible(true);
       }
       else {
         markers[i].setVisible(false);
       }
     }
   }

   </script> 
</body> 
</html>

Screenshot from the above example, after clicking on the "Show Group 2" button:

Google Maps JavaScript API v3 Example: Marker Categories


You basically just need to store references to Marker objects in an array, set their type (school, bus stop, etc.) and then on some event loop through and hide/show as appropriate:

var markers = [];

// create Marker

marker.locType = 'school'; //as appropriate

function hideMarkersOfType(type) {
    var i = markers.length;
    while(i--) {
        if (markers[i].locType == type) {
            markers[i].setVisible(false);
        }
    }
}

// similar function showMarkersOfType() calling markers[i].setVisible(true);

That should be a good start anyway.

Tags:

Javascript

Google Maps

Google Maps Api 3

Google Maps Markers

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