parametric.py 文件源码

def _iter_contrasts(n_subjects, factor_levels, effect_picks):
    """ Aux Function: Setup contrasts """
    from scipy.signal import detrend
    sc = []
    n_factors = len(factor_levels)
    # prepare computation of Kronecker products
    for n_levels in factor_levels:
        # for each factor append
        # 1) column vector of length == number of levels,
        # 2) square matrix with diagonal == number of levels

        # main + interaction effects for contrasts
        sc.append([np.ones([n_levels, 1]),
                   detrend(np.eye(n_levels), type='constant')])

    for this_effect in effect_picks:
        contrast_idx = _get_contrast_indices(this_effect + 1, n_factors)
        c_ = sc[0][contrast_idx[n_factors - 1]]
        for i_contrast in range(1, n_factors):
            this_contrast = contrast_idx[(n_factors - 1) - i_contrast]
            c_ = np.kron(c_, sc[i_contrast][this_contrast])
        df1 = matrix_rank(c_)
        df2 = df1 * (n_subjects - 1)
        yield c_, df1, df2