From c2b9ca1aa60029e01581e273970b54e2b8e48ed1 Mon Sep 17 00:00:00 2001
From: Stefan Appelhoff <stefan.appelhoff@mailbox.org>
Date: Sun, 12 Jul 2026 11:41:13 +0200
Subject: [PATCH] [FIX] ASR: init clean_windows rejection masks before
 one-sided zthresholds

mask1 and mask2 in clean_windows were only assigned inside their
respective `if np.max(zthresholds) > 0` / `if np.min(zthresholds) < 0`
branches, but combined unconditionally via
`np.logical_or.reduce((mask1, mask2, mask3))`. Since zthresholds is a
documented, user-facing parameter, passing a one-sided value (e.g.
[1, 2] or [-5, -1]) skips one branch and raises UnboundLocalError. The
default [-3.5, 5] straddles 0 so both branches run, keeping the bug
latent.

Fix: initialize both masks to all-False (matching the EEGLAB/BCILAB
reference behavior of flagging no windows by default) before the
conditionals, so each criterion that isn't evaluated simply rejects no
windows instead of being undefined.

Added a regression test exercising clean_windows with both one-sided
directions of zthresholds on the eeg_raw.npy fixture.
---
 meegkit/asr.py    |  2 ++
 tests/test_asr.py | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/meegkit/asr.py b/meegkit/asr.py
index 8bdecafb..c421e87e 100755
--- a/meegkit/asr.py
+++ b/meegkit/asr.py
@@ -361,6 +361,8 @@ def clean_windows(X, sfreq, max_bad_chans=0.2, zthresholds=[-3.5, 5],
     swz = np.sort(wz, axis=0)
 
     # determine which windows to remove
+    mask1 = np.zeros(len(offsets), dtype=bool)
+    mask2 = np.zeros(len(offsets), dtype=bool)
     if np.max(zthresholds) > 0:
         mask1 = swz[-(int(max_bad_chans) + 1), :] > np.max(zthresholds)
     if np.min(zthresholds) < 0:
diff --git a/tests/test_asr.py b/tests/test_asr.py
index ca305103..5b833d64 100644
--- a/tests/test_asr.py
+++ b/tests/test_asr.py
@@ -189,6 +189,29 @@ def test_asr_functions(show=False, method="riemann"):
         plt.show()
 
 
+@pytest.mark.parametrize(argnames="zthresholds", argvalues=([1, 2], [-5, -1]))
+def test_clean_windows_one_sided_zthresholds(zthresholds):
+    """Test clean_windows with a one-sided zthresholds.
+
+    Regression test: when zthresholds does not straddle 0 (i.e. both bounds
+    are positive, or both are negative), only one of the two rejection-mask
+    branches in clean_windows runs. The other mask must still be defined
+    (as an all-False "reject nothing" default) so that combining the masks
+    does not raise UnboundLocalError.
+    """
+    raw = np.load(os.path.join(THIS_FOLDER, "data", "eeg_raw.npy"))
+    sfreq = 250
+    # Use a short slice for speed; still exercises the mask logic.
+    X = raw[:, :10 * sfreq]
+
+    clean, sample_mask = clean_windows(X, sfreq, zthresholds=zthresholds)
+
+    assert clean.shape[0] == X.shape[0]
+    assert clean.shape[1] <= X.shape[1]
+    assert sample_mask.shape == (1, X.shape[1])
+    assert sample_mask.dtype == bool
+
+
 @pytest.mark.parametrize(argnames="method", argvalues=("riemann", "euclid"))
 @pytest.mark.parametrize(argnames="reref", argvalues=(False, True))
 def test_asr_class(method, reref, show=False):