Fix concatenating epochs cropped after baseline correction

doc/changes/dev/14188.bugfix.rst

@@ -0,0 +1 @@
+Fix :func:`mne.concatenate_epochs` failing on epochs cropped after baseline correction, by `Kalle Makela`_.

mne/epochs.py

@@ -4907,14 +4907,16 @@ def concatenate_epochs(
         events=events,
         event_id=event_id,
         tmin=tmin,
-        baseline=baseline,
+        baseline=None,
         selection=selection,
         drop_log=drop_log,
         proj=False,
         on_missing="ignore",
         metadata=metadata,
         raw_sfreq=raw_sfreq,
     )
+    # Don't reapply baseline correction. Restore the original baseline metadata.
+    out.baseline = baseline
     out.drop_bad()
     return out
 

mne/tests/test_epochs.py

@@ -3867,6 +3867,17 @@ def test_concatenate_epochs():
     concatenate_epochs([epochs, epochs2], add_offset=True)
 
 
+def test_concatenate_epochs_cropped_baseline():
+    """Test concatenating epochs cropped after baseline correction."""
+    data = np.arange(21.0)[np.newaxis, np.newaxis]
+    epochs = EpochsArray(data, create_info(["x"], 10, "eeg"), tmin=-1)
+    epochs.apply_baseline((-1, 0)).crop(0, 1)
+    expected = epochs.get_data()
+    epochs_conc = concatenate_epochs([epochs])
+    assert epochs_conc.baseline == (-1.0, 0.0)
+    assert_allclose(epochs_conc.get_data(), expected)
+
+
 @pytest.mark.slowtest
 def test_concatenate_epochs_large():
     """Test concatenating epochs on large data."""