set
This sets the coordinates of the Point using the specified coordinate system.
Parameters
r
Depending on the coordinate system specified, this is either the r or x value. In polar coordinates, the r value is the distance from the origin. In Cartesian coordinates, the x value is the distance left/right from the origin.
theta
Depending on the coordinate system specified, this is either the theta or y value. In polar coordinates, the theta value is the angle from the positive x-axis. Increasing theta moves in the counter-clockwise direction. In Cartesian coordinates, the y value is the distance up/down from the origin.
identifier
this specifies what coordinate system to use when setting values.