def _get_pck(self, kp_id, threshold):
    ' Returns pck for one keypoint for the given threshold. '
    if (len(self.data[kp_id]) == 0):
        return None
    data = np.array(self.data[kp_id])
    pck = np.mean((data <= threshold).astype('float'))
    return pck
Returns pck for one keypoint for the given threshold.
def _get_pck(self, kp_id, threshold):
    '  '
    if (len(self.data[kp_id]) == 0):
        return None
    data = np.array(self.data[kp_id])
    pck = np.mean((data <= threshold).astype('float'))
    return pck