def rotate(self, angle, center=(0, 0)):
        """
        Rotate this object.

        Parameters
        ----------
        angle : number
            The angle of rotation (in *radians*).
        center : array-like[2]
            Center point for the rotation.

        Returns
        -------
        out : ``PolygonSet``
            This object.
        """
        ca = numpy.cos(angle)
        sa = numpy.sin(angle)
        sa = numpy.array((-sa, sa))
        c0 = numpy.array(center)
        self.polygons = [(points - c0) * ca + (points - c0)[:, ::-1] * sa + c0
                         for points in self.polygons]
        return self
Rotate this object.

        Parameters
        ----------
        angle : number
            The angle of rotation (in *radians*).
        center : array-like[2]
            Center point for the rotation.

        Returns
        -------
        out : ``PolygonSet``
            This object.