MRG: Backport #10619 and #10620

doc/changes/1.0.inc

@@ -24,6 +24,8 @@ Version 1.0.X
 
 - Retain epochs metadata when using :func:`mne.channels.combine_channels` (:gh:`10504` by `Clemens Brunner`_)
 
+- Fix issue with saving epochs once :func:`~mne.preprocessing.compute_current_source_density` has been used if a rejection threshold was used first (:gh:`10619` by `Alex Rockhill`_ and `Richard Höchenberger`_)
+
 Version 1.0.2 (2022-04-15)
 --------------------------
 - Fix bug where ``theme`` was not handled properly in :meth:`mne.io.Raw.plot` (:gh:`10500` by `Eric Larson`_)

mne/preprocessing/_csd.py

@@ -172,4 +172,12 @@ def compute_current_source_density(inst, sphere='auto', lambda2=1e-5,
     for pick in picks:
         inst.info['chs'][pick].update(coil_type=FIFF.FIFFV_COIL_EEG_CSD,
                                       unit=FIFF.FIFF_UNIT_V_M2)
+
+    # Remove rejection thresholds for EEG
+    if isinstance(inst, BaseEpochs):
+        if inst.reject and 'eeg' in inst.reject:
+            del inst.reject['eeg']
+        if inst.flat and 'eeg' in inst.flat:
+            del inst.flat['eeg']
+
     return inst

mne/preprocessing/tests/test_csd.py

@@ -17,7 +17,8 @@
 from scipy import linalg
 
 from mne.channels import make_dig_montage
-from mne import create_info, EvokedArray, pick_types, Epochs
+from mne import (create_info, EvokedArray, pick_types, Epochs, find_events,
+                 read_epochs)
 from mne.io import read_raw_fif, RawArray
 from mne.io.constants import FIFF
 from mne.utils import object_diff
@@ -183,3 +184,16 @@ def test_csd_fif():
         ch.update(coil_type=FIFF.FIFFV_COIL_EEG, unit=FIFF.FIFF_UNIT_V)
         raw_csd._data[pick] = raw._data[pick]
     assert object_diff(raw.info, raw_csd.info) == ''
+
+
+def test_csd_epochs(tmp_path):
+    """Test making epochs, saving to disk and loading."""
+    raw = read_raw_fif(raw_fname)
+    raw.pick_types(eeg=True, stim=True).load_data()
+    events = find_events(raw)
+    epochs = Epochs(raw, events, reject=dict(eeg=1e-4), preload=True)
+    epochs = compute_current_source_density(epochs)
+    epo_fname = tmp_path / 'test_csd_epo.fif'
+    epochs.save(epo_fname)
+    epochs2 = read_epochs(epo_fname, preload=True)
+    assert_allclose(epochs._data, epochs2._data)