Function _assert_shielding

mne/preprocessing/tests/test_maxwell.py:1067–1080

Assert a minimum shielding factor using empty-room power.

(raw_sss, erm_power, min_factor, max_factor=np.inf, meg="mag")

def _assert_shielding(raw_sss, erm_power, min_factor, max_factor=np.inf, meg="mag"):
    """Assert a minimum shielding factor using empty-room power."""
    __tracebackhide__ = True
    picks = pick_types(raw_sss.info, meg=meg, ref_meg=False)
    if isinstance(erm_power, BaseRaw):
        picks_erm = pick_types(raw_sss.info, meg=meg, ref_meg=False)
        assert_allclose(picks, picks_erm)
        erm_power = np.sqrt((erm_power[picks_erm][0] ** 2).sum())
    sss_power = raw_sss[picks][0].ravel()
    sss_power = np.sqrt(np.sum(sss_power * sss_power))
    factor = erm_power / sss_power
    assert min_factor <= factor < max_factor, (
        f"Shielding factor not {min_factor:0.3f} <= {factor:0.3f} < {max_factor:0.3f}"
    )


@pytest.mark.slowtest