Cannot plot Google Markers after Unset of some elements of JSON Array

I'm trying to add some Markers on Google Map but before I do this I need to unset some elements of JSON Array which I'm doing like this

$json = str_replace('"', '"', $loc);
    foreach ($json as $key => $value)
{
    if(preg_match('/^[X]{2}/',$value['pname'])){
        unset($json[$key]);
    }
}
echo json_encode($json);

before the unset this is how it displays in JS console.log() and plots the Markers

[Object, Object, Object, Object,...]

but after the unset it displays like this and does NOT plot the Markers

Object {2: Object, 20: Object, 40: Object,...}

Can anyone put me in right direction please.

This is the code that produces Markers on Google maps.

makeRequest('get_locations.php', function(data) {
            var data = JSON.parse(data.responseText);
            for (var i = 0; i < data.length; i++) {
                displayResellersPostCode(data[i]);
            }
        });     
        function displayResellersPostCode(location) {
            if (parseInt(location.lat) == 0) {
              geocoder.geocode( { 'pcode1': location.pcode1 }, function(results, status) {
                  if (status == google.maps.GeocoderStatus.OK) {
                       var marker = new google.maps.Marker({
                          map: map, 
                          position: results[0].geometry.location,
                          title: location.uname
                      }); 
                  }
              });
             } else {
                 var position = new google.maps.LatLng(parseFloat(location.latitude), parseFloat(location.longitude));
                 var marker = new google.maps.Marker({
                     map: map, 
                     position: position,
                     title: location.uname
                 }); 
             } 
         }