Update clustered markers in Google Map with map filters

I just create a google map with markers and a select to filter those markers by category

    #map-canvas {
    width: 500px;
    height: 500px;
}
<script src="https://maps.googleapis.com/maps/api/js?key=&v=3.0&sensor=true&language=ee&dummy=dummy.js"></script>
<div id="map-canvas"></div>
<select id="type" onchange="filterMarkers(this.value);">
    <option value="">Please select category</option>
    <option value="second">second</option>
    <option value="car">car</option>
    <option value="third">third</option>
</select>

and the js:

var gmarkers1 = [];
var markers1 = [];
var infowindow = new google.maps.InfoWindow({
    content: ''
});

// Our markers
markers1 = [
    ['0', 'Title 1', 52.4357808, 4.991315699999973, 'car'],
    ['1', 'Title 2', 52.4357808, 4.981315699999973, 'third'],
    ['2', 'Title 3', 52.4555687, 5.039231599999994, 'car'],
    ['3', 'Title 4', 52.4555687, 5.029231599999994, 'second']
];

/**
 * Function to init map
 */

function initialize() {
    var center = new google.maps.LatLng(52.4357808, 4.991315699999973);
    var mapOptions = {
        zoom: 12,
        center: center,
        mapTypeId: google.maps.MapTypeId.TERRAIN
    };

    map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
    for (i = 0; i < markers1.length; i++) {
        addMarker(markers1[i]);
    }
}

/**
 * Function to add marker to map
 */

function addMarker(marker) {
    var category = marker[4];
    var title = marker[1];
    var pos = new google.maps.LatLng(marker[2], marker[3]);
    var content = marker[1];

    marker1 = new google.maps.Marker({
        title: title,
        position: pos,
        category: category,
        map: map
    });

    gmarkers1.push(marker1);

    // Marker click listener
    google.maps.event.addListener(marker1, 'click', (function (marker1, content) {
        return function () {
            console.log('Gmarker 1 gets pushed');
            infowindow.setContent(content);
            infowindow.open(map, marker1);
            map.panTo(this.getPosition());
            map.setZoom(15);
        }
    })(marker1, content));
}

/**
 * Function to filter markers by category
 */

filterMarkers = function (category) {
    for (i = 0; i < markers1.length; i++) {
        marker = gmarkers1[i];
        // If is same category or category not picked
        if (marker.category == category || category.length === 0) {
            marker.setVisible(true);
        }
        // Categories don't match 
        else {
            marker.setVisible(false);
        }
    }
}

// Init map
initialize();

I'm trying to cluster markers using the MarkerClusterer function. So I added as is shown here:

function initialize() {
    var center = new google.maps.LatLng(52.4357808, 4.991315699999973);
    var mapOptions = {
        zoom: 12,
        center: center,
        mapTypeId: google.maps.MapTypeId.TERRAIN
    };

    map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
    for (i = 0; i < markers1.length; i++) {
        addMarker(markers1[i]);
    }
    var markerCluster = new MarkerClusterer(map, gmarkers1, {imagePath: 'MY_CUSTOM_DIR/images/m'});
}

Now this works greats. Markers are grouped, however, when I filter by category, the clusters are not updated. I have tried to read some tutorials about the repaint() function but I can solve it.

Solution

If you clear out the MarkerClusterer (MarkerCluster.clearMarkers()), then re-add the ones that you want visible, it works for me.

filterMarkers = function(category) {
  var newmarkers = [];
  for (i = 0; i < markers1.length; i++) {
    marker = gmarkers1[i];
    // If is same category or category not picked
    if (marker.category == category || category.length === 0) {
      newmarkers.push(marker);
    }
  }
  markerCluster.clearMarkers();
  markerCluster.addMarkers(newmarkers);
}

proof of concept fiddle

code snippet:

/**
 * Function to init map
 */
function initialize() {
  var center = new google.maps.LatLng(52.4357808, 4.991315699999973);
  var mapOptions = {
    zoom: 12,
    center: center,
    mapTypeId: google.maps.MapTypeId.TERRAIN
  };

  map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
  for (i = 0; i < markers1.length; i++) {
    addMarker(markers1[i]);
  }
  markerCluster = new MarkerClusterer(map, gmarkers1, {
    imagePath: 'https://cdn.rawgit.com/googlemaps/v3-utility-library/master/markerclustererplus/images/m'
  });
}

/**
 * Function to add marker to map
 */
function addMarker(marker) {
  var category = marker[4];
  var title = marker[1];
  var pos = new google.maps.LatLng(marker[2], marker[3]);
  var content = marker[1];

  marker1 = new google.maps.Marker({
    title: title,
    position: pos,
    category: category,
    map: map
  });

  gmarkers1.push(marker1);

  // Marker click listener
  google.maps.event.addListener(marker1, 'click', (function(marker1, content) {
    return function() {
      console.log('Gmarker 1 gets pushed');
      infowindow.setContent(content);
      infowindow.open(map, marker1);
      map.panTo(this.getPosition());
      map.setZoom(15);
    }
  })(marker1, content));
}

/**
 * Function to filter markers by category
 */
filterMarkers = function(category) {
  var newmarkers = [];
  for (i = 0; i < markers1.length; i++) {
    marker = gmarkers1[i];
    // If is same category or category not picked
    if (marker.category == category || category.length === 0) {
      newmarkers.push(marker);
    }
  }
  markerCluster.clearMarkers();
  markerCluster.addMarkers(newmarkers);
}
google.maps.event.addDomListener(window, "load", initialize);

var gmarkers1 = [];
var markers1 = [];
var infowindow = new google.maps.InfoWindow({
  content: ''
});
var markerCluster;

// Our markers
markers1 = [
  ['0', 'Title 1', 52.4357808, 4.991315699999973, 'car'],
  ['1', 'Title 2', 52.4357808, 4.981315699999973, 'third'],
  ['2', 'Title 3', 52.4555687, 5.039231599999994, 'car'],
  ['3', 'Title 4', 52.4555687, 5.029231599999994, 'second']
];

body,
html {
  height: 100%;
  width: 100%;
  margin: 0;
  padding: 0;
}
#map-canvas {
  width: 100%;
  height: 95%;
}

<script src="https://unpkg.com/@google/markerclustererplus@4.0.1/dist/markerclustererplus.min.js"></script>
<script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk"></script>
<div id="map-canvas"></div>
<select id="type" onchange="filterMarkers(this.value);">
  <option value="">Please select category</option>
  <option value="second">second</option>
  <option value="car">car</option>
  <option value="third">third</option>
</select>