BUG: Fix bug with sensor_colors

doc/changes/devel.rst

@@ -31,6 +31,7 @@ Enhancements
 - Add the possibility to provide a float between 0 and 1 as ``n_grad``, ``n_mag`` and ``n_eeg`` in `~mne.compute_proj_raw`, `~mne.compute_proj_epochs` and `~mne.compute_proj_evoked` to select the number of vectors based on the cumulative explained variance (:gh:`11919` by `Mathieu Scheltienne`_)
 - Added support for Artinis fNIRS data files to :func:`mne.io.read_raw_snirf` (:gh:`11926` by `Robert Luke`_)
 - Add helpful error messages when using methods on empty :class:`mne.Epochs`-objects (:gh:`11306` by `Martin Schulz`_)
+- Add support for passing a :class:`python:dict` as ``sensor_color`` to specify per-channel-type colors in :func:`mne.viz.plot_alignment` (:gh:`12067` by `Eric Larson`_)
 - Add inferring EEGLAB files' montage unit automatically based on estimated head radius using :func:`read_raw_eeglab(..., montage_units="auto") <mne.io.read_raw_eeglab>` (:gh:`11925` by `Jack Zhang`_, :gh:`11951` by `Eric Larson`_)
 - Add :class:`~mne.time_frequency.EpochsSpectrumArray` and :class:`~mne.time_frequency.SpectrumArray` to support creating power spectra from :class:`NumPy array <numpy.ndarray>` data (:gh:`11803` by `Alex Rockhill`_)
 - Add support for writing forward solutions to HDF5 and convenience function :meth:`mne.Forward.save` (:gh:`12036` by `Eric Larson`_)
@@ -56,6 +57,7 @@ Bugs
 - Fix bug with axis clip box boundaries in :func:`mne.viz.plot_evoked_topo` and related functions (:gh:`11999` by `Eric Larson`_)
 - Fix bug with ``subject_info`` when loading data from and exporting to EDF file (:gh:`11952` by `Paul Roujansky`_)
 - Fix bug with delayed checking of :class:`info["bads"] <mne.Info>` (:gh:`12038` by `Eric Larson`_)
+- Fix bug with :func:`mne.viz.plot_alignment` where ``sensor_colors`` were not handled properly on a per-channel-type basis (:gh:`12067` by `Eric Larson`_)
 - Fix handling of channel information in annotations when loading data from and exporting to EDF file (:gh:`11960` :gh:`12017` :gh:`12044` by `Paul Roujansky`_)
 - Add missing ``overwrite`` and ``verbose`` parameters to :meth:`Transform.save() <mne.transforms.Transform.save>` (:gh:`12004` by `Marijn van Vliet`_)
 - Fix parsing of eye-link :class:`~mne.Annotations` when ``apply_offsets=False`` is provided to :func:`~mne.io.read_raw_eyelink` (:gh:`12003` by `Mathieu Scheltienne`_)

doc/conf.py

@@ -200,7 +200,7 @@
     "path-like": ":term:`path-like`",
     "array-like": ":term:`array_like <numpy:array_like>`",
     "Path": ":class:`python:pathlib.Path`",
-    "bool": ":class:`python:bool`",
+    "bool": ":ref:`python:typebool`",
     # Matplotlib
     "colormap": ":ref:`colormap <matplotlib:colormaps>`",
     "color": ":doc:`color <matplotlib:api/colors_api>`",

mne/defaults.py

@@ -227,6 +227,7 @@
     coreg=dict(
         mri_fid_opacity=1.0,
         dig_fid_opacity=1.0,
+        # go from unit scaling (e.g., unit-radius sphere) to meters
         mri_fid_scale=5e-3,
         dig_fid_scale=8e-3,
         extra_scale=4e-3,
@@ -235,6 +236,8 @@
         eegp_height=0.1,
         ecog_scale=5e-3,
         seeg_scale=5e-3,
+        meg_scale=1.0,  # sensors are already in SI units
+        ref_meg_scale=1.0,
         dbs_scale=5e-3,
         fnirs_scale=5e-3,
         source_scale=5e-3,

mne/gui/_coreg.py

@@ -835,7 +835,7 @@ def _redraw(self, *, verbose=None):
             mri_fids=self._add_mri_fiducials,
             hsp=self._add_head_shape_points,
             hpi=self._add_hpi_coils,
-            eeg=self._add_eeg_channels,
+            eeg=self._add_eeg_fnirs_channels,
             head_fids=self._add_head_fiducials,
             helmet=self._add_helmet,
         )
@@ -1217,7 +1217,7 @@ def _add_head_shape_points(self):
             hsp_actors = None
         self._update_actor("head_shape_points", hsp_actors)
 
-    def _add_eeg_channels(self):
+    def _add_eeg_fnirs_channels(self):
         if self._eeg_channels:
             eeg = ["original"]
             picks = pick_types(self._info, eeg=(len(eeg) > 0), fnirs=True)
@@ -1240,8 +1240,7 @@ def _add_eeg_channels(self):
                     check_inside=self._check_inside,
                     nearest=self._nearest,
                 )
-                sens_actors = actors["eeg"]
-                sens_actors.extend(actors["fnirs"])
+                sens_actors = sum(actors.values(), list())
             else:
                 sens_actors = None
         else:

mne/utils/docs.py

@@ -3966,6 +3966,22 @@ def _reflow_param_docstring(docstring, has_first_line=True, width=75):
     automatically generated, corresponding to all non-zero events.
 """
 
+docdict[
+    "sensor_colors"
+] = """
+sensor_colors : array-like of color | dict | None
+    Colors to use for the sensor glyphs. Can be None (default) to use default colors.
+    A dict should provide the colors (values) for each channel type (keys), e.g.::
+
+        dict(eeg=eeg_colors)
+
+    Where the value (``eeg_colors`` above) can be broadcast to an array of colors with
+    length that matches the number of channels of that type, i.e., is compatible with
+    :func:`matplotlib.colors.to_rgba_array`. A few examples of this for the case above
+    are the string ``"k"``, a list of ``n_eeg`` color strings, or an NumPy ndarray of
+    shape ``(n_eeg, 3)`` or ``(n_eeg, 4)``.
+"""
+
 docdict[
     "sensors_topomap"
 ] = """

mne/viz/_3d.py

@@ -9,6 +9,7 @@
 #
 # License: Simplified BSD
 
+from collections import defaultdict
 import os
 import os.path as op
 import warnings
@@ -604,11 +605,10 @@ def plot_alignment(
         .. versionadded:: 0.16
         .. versionchanged:: 1.0
            Defaults to ``'terrain'``.
-    sensor_colors : array-like | None
-        Colors to use for the sensor glyphs. Can be list-like of color strings
-        (length ``n_sensors``) or array-like of RGB(A) values (shape
-        ``(n_sensors, 3)`` or ``(n_sensors, 4)``). ``None`` (the default) uses
-        the default sensor colors for the :func:`~mne.viz.plot_alignment` GUI.
+    %(sensor_colors)s
+
+        .. versionchanged:: 1.6
+            Support for passing a ``dict`` was added.
     %(verbose)s
 
     Returns
@@ -1437,29 +1437,16 @@ def _plot_sensors(
     sensor_colors=None,
 ):
     """Render sensors in a 3D scene."""
+    from matplotlib.colors import to_rgba_array
+
     defaults = DEFAULTS["coreg"]
     ch_pos, sources, detectors = _ch_pos_in_coord_frame(
         pick_info(info, picks), to_cf_t=to_cf_t, warn_meg=warn_meg
     )
 
-    actors = dict(
-        meg=list(),
-        ref_meg=list(),
-        eeg=list(),
-        fnirs=list(),
-        ecog=list(),
-        seeg=list(),
-        dbs=list(),
-    )
-    locs = dict(
-        eeg=list(),
-        fnirs=list(),
-        ecog=list(),
-        seeg=list(),
-        source=list(),
-        detector=list(),
-    )
-    scalar = 1 if units == "m" else 1e3
+    actors = defaultdict(lambda: list())
+    locs = defaultdict(lambda: list())
+    unit_scalar = 1 if units == "m" else 1e3
     for ch_name, ch_coord in ch_pos.items():
         ch_type = channel_type(info, info.ch_names.index(ch_name))
         # for default picking
@@ -1471,119 +1458,126 @@ def _plot_sensors(
         plot_sensors = (ch_type != "fnirs" or "channels" in fnirs) and (
             ch_type != "eeg" or "original" in eeg
         )
-        color = defaults[ch_type + "_color"]
         # plot sensors
         if isinstance(ch_coord, tuple):  # is meg, plot coil
-            verts, triangles = ch_coord
-            actor, _ = renderer.surface(
-                surface=dict(rr=verts * scalar, tris=triangles),
-                color=color,
-                opacity=0.25,
-                backface_culling=True,
-            )
-            actors[ch_type].append(actor)
-        else:
-            if plot_sensors:
-                locs[ch_type].append(ch_coord)
+            ch_coord = dict(rr=ch_coord[0] * unit_scalar, tris=ch_coord[1])
+        if plot_sensors:
+            locs[ch_type].append(ch_coord)
         if ch_name in sources and "sources" in fnirs:
             locs["source"].append(sources[ch_name])
         if ch_name in detectors and "detectors" in fnirs:
             locs["detector"].append(detectors[ch_name])
+        # Plot these now
         if ch_name in sources and ch_name in detectors and "pairs" in fnirs:
             actor, _ = renderer.tube(  # array of origin and dest points
-                origin=sources[ch_name][np.newaxis] * scalar,
-                destination=detectors[ch_name][np.newaxis] * scalar,
-                radius=0.001 * scalar,
+                origin=sources[ch_name][np.newaxis] * unit_scalar,
+                destination=detectors[ch_name][np.newaxis] * unit_scalar,
+                radius=0.001 * unit_scalar,
             )
             actors[ch_type].append(actor)
+            del ch_type
 
-    # add sensors
-    for sensor_type in locs.keys():
-        if len(locs[sensor_type]) > 0:
-            sens_loc = np.array(locs[sensor_type])
-            sens_loc = sens_loc[~np.isnan(sens_loc).any(axis=1)]
-            scale = defaults[sensor_type + "_scale"]
-            if sensor_colors is None:
-                color = defaults[sensor_type + "_color"]
+    # now actually plot the sensors
+    extra = ""
+    types = (dict, None)
+    if len(locs) == 0:
+        return
+    elif len(locs) == 1:
+        # Upsample from array-like to dict when there is one channel type
+        extra = "(or array-like since only one sensor type is plotted)"
+        if sensor_colors is not None and not isinstance(sensor_colors, dict):
+            sensor_colors = {
+                list(locs)[0]: to_rgba_array(sensor_colors),
+            }
+    else:
+        extra = f"when more than one channel type ({list(locs)}) is plotted"
+    _validate_type(sensor_colors, types, "sensor_colors", extra=extra)
+    del extra, types
+    if sensor_colors is None:
+        sensor_colors = dict()
+    assert isinstance(sensor_colors, dict)
+    for ch_type, sens_loc in locs.items():
+        assert len(sens_loc)  # should be guaranteed above
+        colors = to_rgba_array(sensor_colors.get(ch_type, defaults[ch_type + "_color"]))
+        _check_option(
+            f"len(sensor_colors[{repr(ch_type)}])",
+            colors.shape[0],
+            (len(sens_loc), 1),
+        )
+        scale = defaults[ch_type + "_scale"] * unit_scalar
+        if isinstance(sens_loc[0], dict):  # meg coil
+            if len(colors) == 1:
+                colors = [colors[0]] * len(sens_loc)
+            for surface, color in zip(sens_loc, colors):
+                actor, _ = renderer.surface(
+                    surface=surface,
+                    color=color[:3],
+                    opacity=sensor_opacity * color[3],
+                    backface_culling=False,  # visible from all sides
+                )
+                actors[ch_type].append(actor)
+        else:
+            sens_loc = np.array(sens_loc, float)
+            mask = ~np.isnan(sens_loc).any(axis=1)
+            if len(colors) == 1:
+                # Single color mode (one actor)
                 actor, _ = _plot_glyphs(
                     renderer=renderer,
-                    loc=sens_loc * scalar,
-                    color=color,
-                    scale=scale * scalar,
-                    opacity=sensor_opacity,
+                    loc=sens_loc[mask] * unit_scalar,
+                    color=colors[0, :3],
+                    scale=scale,
+                    opacity=sensor_opacity * colors[0, 3],
                     orient_glyphs=orient_glyphs,
                     scale_by_distance=scale_by_distance,
                     project_points=project_points,
                     surf=surf,
                     check_inside=check_inside,
                     nearest=nearest,
                 )
-                if sensor_type in ("source", "detector"):
-                    sensor_type = "fnirs"
-                actors[sensor_type].append(actor)
+                actors[ch_type].append(actor)
             else:
-                actor_list = []
-                for idx_sen in range(sens_loc.shape[0]):
-                    sensor_colors = np.asarray(sensor_colors)
-                    if (
-                        sensor_colors.ndim not in (1, 2)
-                        or sensor_colors.shape[0] != sens_loc.shape[0]
-                    ):
-                        raise ValueError(
-                            "sensor_colors should either be None or be "
-                            "array-like with shape (n_sensors,) or "
-                            "(n_sensors, 3) or (n_sensors, 4). Got shape "
-                            f"{sensor_colors.shape}."
-                        )
-                    color = sensor_colors[idx_sen]
-
+                # Multi-color mode (multiple actors)
+                for loc, color, usable in zip(sens_loc, colors, mask):
+                    if not usable:
+                        continue
                     actor, _ = _plot_glyphs(
                         renderer=renderer,
-                        loc=(sens_loc * scalar)[idx_sen, :],
-                        color=color,
-                        scale=scale * scalar,
-                        opacity=sensor_opacity,
+                        loc=loc * unit_scalar,
+                        color=color[:3],
+                        scale=scale,
+                        opacity=sensor_opacity * color[3],
                         orient_glyphs=orient_glyphs,
                         scale_by_distance=scale_by_distance,
                         project_points=project_points,
                         surf=surf,
                         check_inside=check_inside,
                         nearest=nearest,
                     )
-                    actor_list.append(actor)
-                if sensor_type in ("source", "detector"):
-                    sensor_type = "fnirs"
-                actors[sensor_type].append(actor_list)
-
-    # add projected eeg
-    eeg_indices = pick_types(info, eeg=True)
-    if eeg_indices.size > 0 and "projected" in eeg:
-        logger.info("Projecting sensors to the head surface")
-        eeg_loc = np.array([ch_pos[info.ch_names[idx]] for idx in eeg_indices])
-        eeg_loc = eeg_loc[~np.isnan(eeg_loc).any(axis=1)]
-        eegp_loc, eegp_nn = _project_onto_surface(
-            eeg_loc, head_surf, project_rrs=True, return_nn=True
-        )[2:4]
-        del eeg_loc
-        eegp_loc *= scalar
-        scale = defaults["eegp_scale"] * scalar
-        actor, _ = renderer.quiver3d(
-            x=eegp_loc[:, 0],
-            y=eegp_loc[:, 1],
-            z=eegp_loc[:, 2],
-            u=eegp_nn[:, 0],
-            v=eegp_nn[:, 1],
-            w=eegp_nn[:, 2],
-            color=defaults["eegp_color"],
-            mode="cylinder",
-            scale=scale,
-            opacity=0.6,
-            glyph_height=defaults["eegp_height"],
-            glyph_center=(0.0, -defaults["eegp_height"] / 2.0, 0),
-            glyph_resolution=20,
-            backface_culling=True,
-        )
-        actors["eeg"].append(actor)
+                    actors[ch_type].append(actor)
+        if ch_type == "eeg" and "projected" in eeg:
+            logger.info("Projecting sensors to the head surface")
+            eegp_loc, eegp_nn = _project_onto_surface(
+                sens_loc[mask], head_surf, project_rrs=True, return_nn=True
+            )[2:4]
+            eegp_loc *= unit_scalar
+            actor, _ = renderer.quiver3d(
+                x=eegp_loc[:, 0],
+                y=eegp_loc[:, 1],
+                z=eegp_loc[:, 2],
+                u=eegp_nn[:, 0],
+                v=eegp_nn[:, 1],
+                w=eegp_nn[:, 2],
+                color=defaults["eegp_color"],
+                mode="cylinder",
+                scale=defaults["eegp_scale"] * unit_scalar,
+                opacity=0.6,
+                glyph_height=defaults["eegp_height"],
+                glyph_center=(0.0, -defaults["eegp_height"] / 2.0, 0),
+                glyph_resolution=20,
+                backface_culling=True,
+            )
+            actors["eeg"].append(actor)
+    actors = dict(actors)  # get rid of defaultdict
 
     return actors
 

mne/viz/_brain/_brain.py

@@ -2763,6 +2763,8 @@ def add_sensors(
         seeg=True,
         dbs=True,
         max_dist=0.004,
+        *,
+        sensor_colors=None,
         verbose=None,
     ):
         """Add mesh objects to represent sensor positions.
@@ -2778,6 +2780,9 @@ def add_sensors(
         %(seeg)s
         %(dbs)s
         %(max_dist_ieeg)s
+        %(sensor_colors)s
+
+            .. versionadded:: 1.6
         %(verbose)s
 
         Notes
@@ -2832,6 +2837,7 @@ def add_sensors(
                     warn_meg,
                     head_surf,
                     self._units,
+                    sensor_colors=sensor_colors,
                 )
                 for item, actors in sensors_actors.items():
                     for actor in actors: