'contrast/restriction matrix for no interaction'

def r_nointer(self):

    nia = self.n_interaction
    R_nointer = np.hstack((np.zeros((nia, (self.nvars - nia))), np.eye(nia)))
    R_nointer_transf = self.transform.inv_dot_right(R_nointer)
    self.R_nointer_transf = R_nointer_transf
    return R_nointer_transf
