Fix copy-view issue in epochs

mne/epochs.py

@@ -1588,6 +1588,7 @@ def _get_data(
         units=None,
         tmin=None,
         tmax=None,
+        copy=False,
         on_empty="warn",
         verbose=None,
     ):
@@ -1648,6 +1649,8 @@ def _get_data(
         if self.preload:
             # we will store our result in our existing array
             data = self._data
+            if copy:
+                data = data.copy()
         else:
             # we start out with an empty array, allocate only if necessary
             data = np.empty((0, len(self.info["ch_names"]), len(self.times)))
@@ -1796,7 +1799,9 @@ def _detrend_picks(self):
             return []
 
     @fill_doc
-    def get_data(self, picks=None, item=None, units=None, tmin=None, tmax=None):
+    def get_data(
+        self, picks=None, item=None, units=None, tmin=None, tmax=None, copy=True
+    ):
         """Get all epochs as a 3D array.
 
         Parameters
@@ -1821,13 +1826,19 @@ def get_data(self, picks=None, item=None, units=None, tmin=None, tmax=None):
             End time of data to get in seconds.
 
             .. versionadded:: 0.24.0
+        copy : bool | None
+            Whether to return a copy of the object's data, or (if possible) a view.
+            See :std:label:`basics.copies-and-views <numpy:basics.copies-and-views>`
+            for an explanation. Default is ``True``.
 
         Returns
         -------
         data : array of shape (n_epochs, n_channels, n_times)
             A view on epochs data.
         """
-        return self._get_data(picks=picks, item=item, units=units, tmin=tmin, tmax=tmax)
+        return self._get_data(
+            picks=picks, item=item, units=units, tmin=tmin, tmax=tmax, copy=copy
+        )
 
     @verbose
     def apply_function(

mne/tests/test_epochs.py

@@ -321,6 +321,13 @@ def test_get_data():
     with pytest.raises(TypeError, match="tmax .* float, None"):
         epochs.get_data(tmin=1, tmax=np.ones(5))
 
+    # Test copy
+    data = epochs.get_data(copy=True)
+    assert not np.shares_memory(data, epochs._data)
+
+    data = epochs.get_data(copy=False)
+    assert np.shares_memory(data, epochs._data)
+
 
 def test_hierarchical():
     """Test hierarchical access."""
@@ -1033,7 +1040,7 @@ def test_epochs_baseline_basic(preload, tmp_path):
     epochs = mne.Epochs(raw, events, None, 0, 1e-3, baseline=None, preload=preload)
     epochs.drop_bad()
     epochs_nobl = epochs.copy()
-    epochs_data = epochs.get_data()
+    epochs_data = epochs.get_data(copy=False)
     assert epochs_data.shape == (1, 2, 2)
     expected = data.copy()
     assert_array_equal(epochs_data[0], expected)

mne/viz/tests/test_epochs.py

@@ -415,7 +415,7 @@ def test_plot_psd_epochs(epochs):
     fig = spectrum.plot_topomap(bands=[(20, "20 Hz"), (15, 25, "15-25 Hz")])
     # test with a flat channel
     err_str = "for channel %s" % epochs.ch_names[2]
-    epochs.get_data()[0, 2, :] = 0
+    epochs.get_data(copy=False)[0, 2, :] = 0
     for dB in [True, False]:
         with pytest.warns(UserWarning, match=err_str):
             epochs.compute_psd().plot(dB=dB)