How to get angle between duct and coordinate system

[raysonchan0305]

Hi everyone, I am trying to write a Python script to place family according to Duct element including the rotation of the duct. But I am not success to get the angle between the duct and the coordinate system.
Can anyone advise me how can I place family which align the duct element?

[ridaabderrahmane]

 var curve = (duct.Location as LocationCurve).Curve;

var direction = (curve as Line).Direction;

var angle = direction.AngleTo(XYZ.BasisX)); // the angle between the duct and the X axis.

 You can rotate ur family instance with this angle around The Z axis.