Circle(radius, center=None, normal=None, frame=None)  

The Circle class provides an interface for creating a circle segmentation. 
A circle segmentation is defined by a radius, a 3D point defining its      
center and a normal. The normal defines its orientation (i.e. the plane the
circle lies in).                                                           

A Circle object is created using a radius, center and normal or a PathFrame
object.                                                                    

A PathFrame object contains a path's interpolating spline (curve points)   
position, tangent, and normal data at a given location. The position is    
used for the circle center, the tangent for its normal.

Args: 
  radius (float): The circle radius. 
  center (list([float,float,float]): The circle center. 
  normal(list([float,float,float]): The circle normal direction. 
  frame (Optional[PathFrame]): A PathFrame object defing the circle's   
     center and coordinate frame. 

get_center() 
  
  Get the circle segmentation center. 
  
  Returns (list([float,float,float])): The circle center. 

get_id()  
   
   Get the contour ID. 
   
   Returns int: The contour ID. 

get_normal() 
   
   Get the circle segmentation normal. 
   
   Returns (list([float,float,float]): The circle normal. 
   

get_path_point()  
   
   Get the contour path point. 
   
   Returns dict(pos:[x,y,z], tangent:[x,y,z], rotation:[x,y,z]): The contour path point. 

get_points()  
   
   Get the segmentation contour points. 
   
   Returns list([x,y,z]): The list of contour points. 

get_vtk_polydata()  
   
   Get the contour type. 
   
   Returns (str): contour type. 

get_radius(r) 
   
   Get the radius for a circle segmentation. 
   
   Returns (float): The radius of the circle. 

get_type()  
   
   Get the contour type. 
   
   Returns (str): contour type. 

set_center(center) 
   
   Set the circle segmentation center. 
   
   Args: 
     center (list([float,float,float]): The circle center. 
   

set_frame(frame) 
   
   Set the circle segmentation coordinate frame using a PathFrame object. 
   
   Args: 
     frame (PathFrame): The PathFrame object defing the circle's center and coordinate frame. 
   

set_normal(normal)  
   
   Set the circle segmentation normal. 
   
   Args: 
     normal (list([float,float,float]): The circle normal. 
   

set_radius(radius) 
   
   Set the radius for a circle segmentation. 
   
   Args: 
     radius (float): The radius of the circle.