add_filter('oum_location_data', function ( $location_data, $post_id ) {

  // Example: Change marker icon based on custom logic
  if ( $post_id == 123 ) {
    $location_data['icon'] = 'https://example.com/custom-marker.png';
  }

  // You can modify any property of $location_data:
  // - icon: marker icon URL (works for map markers and list view)
  // - title, lat, lng, zoom, types, post_id, address, text, image, audio, video, custom_fields, votes, etc.
  // - content: plain text for the map marker search only (not the popup HTML). Full bubble markup is built
  //   on the server and can be changed with the oum_location_bubble_content filter (or oum_location_bubble_image).

  return $location_data;
}, 10, 2);