pie.startAngle()

pie.startAngle([angle])

If angle is specified, sets the overall start angle of the pie to the specified function or number and returns this pie generator. If angle is not specified, returns the current start angle accessor, which defaults to:

function startAngle() {
  return 0;
}

The start angle here means the overall start angle of the pie, i.e., the start angle of the first arc. The start angle accessor is invoked once, being passed the same arguments and this context as the pie generator. The units of angle are arbitrary, but if you plan to use the pie generator in conjunction with an arc generator, you should specify an angle in radians, with 0 at -y (12 o’clock) and positive angles proceeding clockwise.