[FIX] Bug loading projections in CSD h5 files.

doc/changes/latest.inc

@@ -31,6 +31,7 @@ Enhancements
 
 Bugs
 ~~~~
+- Fix bug in :func:`mne.time_frequency.read_csd` that returned `mne.time_frequency.CrossSpectralDensity.projs` as a list of dict instead of `mne.proj.Projection` (:gh:`11072` by :newcontrib:`Chetan Gohil`)
 - Fix bug in :func:`mne.decoding.TimeFrequency` that prevented cloning if constructor arguments were modified (:gh:`11004` by :newcontrib:`Daniel Carlström Schad`)
 - Fix bug in :class:`mne.viz.Brain` constructor where the first argument was named ``subject_id`` instead of ``subject`` (:gh:`11049` by `Eric Larson`_)
 - Document ``height`` and ``weight`` keys of  ``subject_info`` entry in :class:`mne.Info` (:gh:`11019` by :newcontrib:`Sena Er`)

doc/changes/names.inc

@@ -66,6 +66,8 @@
 
 .. _Cathy Nangini: https://github.com/KatiRG
 
+.. _Chetan Gohil: https://github.com/cgohil8
+
 .. _Chris Bailey: https://github.com/cjayb
 
 .. _Chris Holdgraf: https://chrisholdgraf.com

mne/time_frequency/csd.py

@@ -607,6 +607,12 @@ def read_csd(fname):
         fname += '.h5'
 
     csd_dict = read_hdf5(fname, title='conpy')
+
+    if csd_dict["projs"] is not None:
+        # Avoid circular import
+        from ..proj import Projection
+        csd_dict["projs"] = [Projection(**proj) for proj in csd_dict["projs"]]
+
     return CrossSpectralDensity(**csd_dict)
 
 

mne/time_frequency/tests/test_csd.py

@@ -16,6 +16,7 @@
                                 CrossSpectralDensity, read_csd,
                                 pick_channels_csd, psd_multitaper)
 from mne.time_frequency.csd import _sym_mat_to_vector, _vector_to_sym_mat
+from mne.proj import compute_proj_raw, Projection
 
 base_dir = op.join(op.dirname(__file__), '..', '..', 'io', 'tests', 'data')
 raw_fname = op.join(base_dir, 'test_raw.fif')
@@ -223,17 +224,25 @@ def test_csd_get_data():
 @requires_version('h5io')
 def test_csd_save(tmp_path):
     """Test saving and loading a CrossSpectralDensity."""
-    csd = _make_csd()
-    tempdir = str(tmp_path)
-    fname = op.join(tempdir, 'csd.h5')
+    raw = mne.io.read_raw_fif(raw_fname)
+    events = mne.find_events(raw)
+    picks = mne.pick_types(raw.info, meg='grad')
+    projs = compute_proj_raw(raw, n_grad=1, n_mag=1, n_eeg=1, reject=None)
+    raw.add_proj(projs)
+    epochs = mne.Epochs(raw, events, event_id=1, tmin=-0.2, tmax=1,
+                        picks=picks, baseline=(None, 0),
+                        reject=dict(grad=4000e-13), preload=True)
+    csd = csd_fourier(epochs, fmin=15, fmax=20)
+    fname = op.join(str(tmp_path), 'csd.h5')
     csd.save(fname)
     csd2 = read_csd(fname)
     assert_array_equal(csd._data, csd2._data)
+    assert_array_equal(csd.frequencies, csd2.frequencies)
     assert csd.tmin == csd2.tmin
     assert csd.tmax == csd2.tmax
     assert csd.ch_names == csd2.ch_names
-    assert csd.frequencies == csd2.frequencies
     assert csd._is_sum == csd2._is_sum
+    assert isinstance(csd2.projs[0], Projection)
 
 
 def test_csd_pickle(tmp_path):