Trying to get the layers that are in a group

Rhino Developer
2

I think this extension method should do it:

public static class GroupTableExtensionMethods
{
  /// <summary>
  /// Returns the layer indices of Group members
  /// </summary>
  public static int[] GroupLayers(this GroupTable groupTable, int groupIndex)
  {
    if (groupIndex > 0 && groupIndex < groupTable.Count)
    {
      var rhino_objects = groupTable.GroupMembers(groupIndex);
      var hash_set = new HashSet<int>();
      foreach (var rh_obj in rhino_objects)
        hash_set.Add(rh_obj.Attributes.LayerIndex);
      return hash_set.ToArray();
    }
    return new int[0];
  }
}