BUG: Fix bug with fwd restriction

doc/changes/latest.inc

@@ -27,7 +27,7 @@ Enhancements
 
 Bugs
 ~~~~
-- None yet
+- Fix bug with :func:`mne.forward.restrict_forward_to_label` where cortical patch information was not adjusted (:gh:`11694` by `Eric Larson`_)
 
 API changes
 ~~~~~~~~~~~

mne/forward/forward.py

@@ -1760,7 +1760,7 @@ def restrict_forward_to_stc(fwd, stc, on_missing="ignore"):
     """
     _validate_type(on_missing, str, "on_missing")
     _check_option("on_missing", on_missing, ("ignore", "warn", "raise"))
-    src_sel, _, vertices = _stc_src_sel(fwd["src"], stc, on_missing=on_missing)
+    src_sel, _, _ = _stc_src_sel(fwd["src"], stc, on_missing=on_missing)
     del stc
     return _restrict_forward_to_src_sel(fwd, src_sel)
 
@@ -1844,81 +1844,12 @@ def restrict_forward_to_label(fwd, labels):
         vertices[i] = np.append(vertices[i], label.vertices)
     # Remove duplicates and sort
     vertices = [np.unique(vert_hemi) for vert_hemi in vertices]
-
-    fwd_out = deepcopy(fwd)
-    fwd_out["source_rr"] = np.zeros((0, 3))
-    fwd_out["nsource"] = 0
-    fwd_out["source_nn"] = np.zeros((0, 3))
-    fwd_out["sol"]["data"] = np.zeros((fwd["sol"]["data"].shape[0], 0))
-    fwd_out["_orig_sol"] = np.zeros((fwd["_orig_sol"].shape[0], 0))
-    if fwd["sol_grad"] is not None:
-        fwd_out["sol_grad"]["data"] = np.zeros((fwd["sol_grad"]["data"].shape[0], 0))
-        fwd_out["_orig_sol_grad"] = np.zeros((fwd["_orig_sol_grad"].shape[0], 0))
-    fwd_out["sol"]["ncol"] = 0
-    nuse_lh = fwd["src"][0]["nuse"]
-
-    for i in range(2):
-        fwd_out["src"][i]["vertno"] = np.array([], int)
-        fwd_out["src"][i]["nuse"] = 0
-        fwd_out["src"][i]["inuse"] = fwd["src"][i]["inuse"].copy()
-        fwd_out["src"][i]["inuse"].fill(0)
-        fwd_out["src"][i]["use_tris"] = np.array([[]], int)
-        fwd_out["src"][i]["nuse_tri"] = np.array([0])
-
-        # src_sel is idx to cols in fwd that are in any label per hemi
-        src_sel = np.intersect1d(fwd["src"][i]["vertno"], vertices[i])
-        src_sel = np.searchsorted(fwd["src"][i]["vertno"], src_sel)
-
-        # Reconstruct each src
-        vertno = fwd["src"][i]["vertno"][src_sel]
-        fwd_out["src"][i]["inuse"][vertno] = 1
-        fwd_out["src"][i]["nuse"] += len(vertno)
-        fwd_out["src"][i]["vertno"] = np.where(fwd_out["src"][i]["inuse"])[0]
-
-        # Reconstruct part of fwd that is not sol data
-        src_sel += i * nuse_lh  # Add column shift to right hemi
-        fwd_out["source_rr"] = np.vstack(
-            [fwd_out["source_rr"], fwd["source_rr"][src_sel]]
-        )
-        fwd_out["nsource"] += len(src_sel)
-
-        if is_fixed_orient(fwd):
-            idx = src_sel
-            if fwd["sol_grad"] is not None:
-                idx_grad = (3 * src_sel[:, None] + np.arange(3)).ravel()
-        else:
-            idx = (3 * src_sel[:, None] + np.arange(3)).ravel()
-            if fwd["sol_grad"] is not None:
-                idx_grad = (9 * src_sel[:, None] + np.arange(9)).ravel()
-
-        fwd_out["source_nn"] = np.vstack([fwd_out["source_nn"], fwd["source_nn"][idx]])
-        fwd_out["sol"]["data"] = np.hstack(
-            [fwd_out["sol"]["data"], fwd["sol"]["data"][:, idx]]
-        )
-        if fwd["sol_grad"] is not None:
-            fwd_out["sol_grad"]["data"] = np.hstack(
-                [fwd_out["sol_grad"]["data"], fwd["sol_rad"]["data"][:, idx_grad]]
-            )
-        fwd_out["sol"]["ncol"] += len(idx)
-
-        if is_fixed_orient(fwd, orig=True):
-            idx = src_sel
-            if fwd["sol_grad"] is not None:
-                idx_grad = (3 * src_sel[:, None] + np.arange(3)).ravel()
-        else:
-            idx = (3 * src_sel[:, None] + np.arange(3)).ravel()
-            if fwd["sol_grad"] is not None:
-                idx_grad = (9 * src_sel[:, None] + np.arange(9)).ravel()
-
-        fwd_out["_orig_sol"] = np.hstack(
-            [fwd_out["_orig_sol"], fwd["_orig_sol"][:, idx]]
-        )
-        if fwd["sol_grad"] is not None:
-            fwd_out["_orig_sol_grad"] = np.hstack(
-                [fwd_out["_orig_sol_grad"], fwd["_orig_sol_grad"][:, idx_grad]]
-            )
-
-    return fwd_out
+    vertices = [
+        vert_hemi[np.in1d(vert_hemi, s["vertno"])]
+        for vert_hemi, s in zip(vertices, fwd["src"])
+    ]
+    src_sel, _, _ = _stc_src_sel(fwd["src"], vertices, on_missing="raise")
+    return _restrict_forward_to_src_sel(fwd, src_sel)
 
 
 def _do_forward_solution(

mne/forward/tests/test_forward.py

@@ -44,6 +44,7 @@
 fname_evoked = (
     Path(__file__).parent.parent.parent / "io" / "tests" / "data" / "test-ave.fif"
 )
+label_path = data_path / "MEG" / "sample" / "labels"
 
 
 def assert_forward_allclose(f1, f2, rtol=1e-7):
@@ -318,7 +319,6 @@ def test_restrict_forward_to_label(tmp_path):
     fwd = convert_forward_solution(fwd, surf_ori=True, force_fixed=True, use_cps=True)
     fwd = pick_types_forward(fwd, meg=True)
 
-    label_path = data_path / "MEG" / "sample" / "labels"
     labels = ["Aud-lh", "Vis-rh"]
     label_lh = read_label(label_path / (labels[0] + ".label"))
     label_rh = read_label(label_path / (labels[1] + ".label"))
@@ -344,7 +344,6 @@ def test_restrict_forward_to_label(tmp_path):
     fwd = read_forward_solution(fname_meeg)
     fwd = pick_types_forward(fwd, meg=True)
 
-    label_path = data_path / "MEG" / "sample" / "labels"
     labels = ["Aud-lh", "Vis-rh"]
     label_lh = read_label(label_path / (labels[0] + ".label"))
     label_rh = read_label(label_path / (labels[1] + ".label"))
@@ -375,6 +374,48 @@ def test_restrict_forward_to_label(tmp_path):
     assert_forward_allclose(fwd_out, fwd_out_read)
 
 
+@pytest.mark.parametrize("use_cps", [True, False])
+@testing.requires_testing_data
+def test_restrict_forward_to_label_cps(tmp_path, use_cps):
+    """Test for gh-11689."""
+    label_lh = read_label(label_path / "Aud-lh.label")
+    fwd = read_forward_solution(fname_meeg)
+    convert_forward_solution(
+        fwd, surf_ori=True, force_fixed=False, copy=False, use_cps=use_cps
+    )
+    fwd = pick_types_forward(fwd, meg="mag")
+    fwd_out = restrict_forward_to_label(fwd, label_lh)
+    vert = fwd_out["src"][0]["vertno"][0]
+
+    assert fwd["surf_ori"]
+    assert not is_fixed_orient(fwd)
+    idx = list(fwd["src"][0]["vertno"]).index(vert)
+    assert idx == 126
+    go1 = fwd["_orig_sol"][:, idx * 3 : idx * 3 + 3].copy()
+    gs1 = fwd["sol"]["data"][:, idx * 3 : idx * 3 + 3].copy()
+
+    assert fwd_out["surf_ori"]
+    assert not is_fixed_orient(fwd_out)
+    idx = list(fwd_out["src"][0]["vertno"]).index(vert)
+    assert idx == 0
+    go2 = fwd_out["_orig_sol"][:, idx * 3 : idx * 3 + 3].copy()
+    gs2 = fwd_out["sol"]["data"][:, idx * 3 : idx * 3 + 3].copy()
+    assert_allclose(go2, go1)
+    assert_allclose(gs2, gs1)
+
+    # should be a no-op
+    convert_forward_solution(
+        fwd_out, surf_ori=True, force_fixed=False, copy=False, use_cps=use_cps
+    )
+    assert fwd_out["surf_ori"]
+    assert not is_fixed_orient(fwd_out)
+    assert list(fwd_out["src"][0]["vertno"]).index(vert) == 0
+    go3 = fwd_out["_orig_sol"][:, idx * 3 : idx * 3 + 3].copy()
+    gs3 = fwd_out["sol"]["data"][:, idx * 3 : idx * 3 + 3].copy()
+    assert_allclose(go3, go1)
+    assert_allclose(gs3, gs1)
+
+
 @testing.requires_testing_data
 @requires_mne
 def test_average_forward_solution(tmp_path):

mne/proj.py

@@ -390,7 +390,7 @@ def compute_proj_raw(
 
 @verbose
 def sensitivity_map(
-    fwd, projs=None, ch_type="grad", mode="fixed", exclude=[], verbose=None
+    fwd, projs=None, ch_type="grad", mode="fixed", exclude=(), *, verbose=None
 ):
     """Compute sensitivity map.
 
@@ -420,6 +420,11 @@ def sensitivity_map(
     stc : SourceEstimate | VolSourceEstimate
         The sensitivity map as a SourceEstimate or VolSourceEstimate instance
         for visualization.
+
+    Notes
+    -----
+    When mode is ``'fixed'`` or ``'free'``, the sensitivity map is normalized
+    by its maximum value.
     """
     from scipy import linalg
 
@@ -444,10 +449,7 @@ def sensitivity_map(
     convert_forward_solution(
         fwd, surf_ori=True, force_fixed=False, copy=False, verbose=False
     )
-    if not fwd["surf_ori"] or is_fixed_orient(fwd):
-        raise RuntimeError(
-            "Error converting solution, please notify " "mne-python developers"
-        )
+    assert fwd["surf_ori"] and not is_fixed_orient(fwd)
 
     gain = fwd["sol"]["data"]
 
@@ -477,8 +479,9 @@ def sensitivity_map(
     elif mode in residual_types:
         raise ValueError("No projectors used, cannot compute %s" % mode)
 
-    n_sensors, n_dipoles = gain.shape
+    _, n_dipoles = gain.shape
     n_locations = n_dipoles // 3
+    del n_dipoles
     sensitivity_map = np.empty(n_locations)
 
     for k in range(n_locations):