private Dictionary<ElementId, List<ElementId>> GetElementIds( FilteredElementCollector elements )
{
Dictionary<ElementId, List<ElementId>> dict =
new Dictionary<ElementId, List<ElementId>>();
string fmt = "{0} is hosted by {1}";
foreach( FamilyInstance fi in elements )
{
ElementId id = fi.Id;
ElementId idHost = fi.Host.Id;
Debug.Print( fmt,
Util.ElementDescription( fi ),
ElementDescription( idHost ) );
if( !dict.ContainsKey( idHost ) )
{
dict.Add( idHost, new List<ElementId>() );
}
dict[idHost].Add( id );
}
return dict;
}