BUG: Fix grow_labels (mne-tools#9317)

doc/changes/latest.inc

@@ -239,6 +239,8 @@ Bugs
 
 - Fix bug with :func:`mne.extract_label_time_course` where labels, STCs, and the source space were not checked for compatible ``subject`` attributes (:gh:`9284` by `Eric Larson`_)
 
+- Fix bug with :func:`mne.grow_labels` where ``overlap=False`` could run forever or raise an error (:gh:`9317` by `Eric Larson`_)
+
 - Fix compatibility bugs with :mod:`mne_realtime` (:gh:`8845` by `Eric Larson`_)
 
 - Fix bug with `mne.viz.Brain` where non-inflated surfaces had an X-offset imposed by default (:gh:`8794` by `Eric Larson`_)

mne/label.py

@@ -1573,8 +1573,7 @@ def grow_labels(subject, seeds, extents, hemis, subjects_dir=None, n_jobs=1,
     # make sure the inputs are arrays
     if np.isscalar(seeds):
         seeds = [seeds]
-    # these can have different sizes so need to use object array
-    seeds = np.asarray([np.atleast_1d(seed) for seed in seeds], dtype='O')
+    seeds = [np.atleast_1d(seed) for seed in seeds]
     extents = np.atleast_1d(extents)
     hemis = np.atleast_1d(hemis)
     n_seeds = len(seeds)
@@ -1636,7 +1635,7 @@ def grow_labels(subject, seeds, extents, hemis, subjects_dir=None, n_jobs=1,
     if overlap:
         # create the patches
         parallel, my_grow_labels, _ = parallel_func(_grow_labels, n_jobs)
-        seeds = np.array_split(seeds, n_jobs)
+        seeds = np.array_split(np.array(seeds, dtype='O'), n_jobs)
         extents = np.array_split(extents, n_jobs)
         hemis = np.array_split(hemis, n_jobs)
         names = np.array_split(names, n_jobs)
@@ -1668,7 +1667,7 @@ def _grow_nonoverlapping_labels(subject, seeds_, extents_, hemis, vertices_,
     labels = []
     for hemi in set(hemis):
         hemi_index = (hemis == hemi)
-        seeds = seeds_[hemi_index]
+        seeds = [seed for seed, h in zip(seeds_, hemis) if h == hemi]
         extents = extents_[hemi_index]
         names = names_[hemi_index]
         graph = graphs[hemi]  # distance graph
@@ -1698,6 +1697,10 @@ def _grow_nonoverlapping_labels(subject, seeds_, extents_, hemis, vertices_,
             # add neighbors within allowable distance
             row = graph[vert_from, :]
             for vert_to, dist in zip(row.indices, row.data):
+                # Prevent adding a point that has already been used
+                # (prevents infinite loop)
+                if (vert_to == seeds[label]).any():
+                    continue
                 new_dist = old_dist + dist
 
                 # abort if outside of extent

mne/tests/test_label.py

@@ -845,6 +845,10 @@ def test_grow_labels():
     l1 = l11 + l12
     assert_array_equal(l1.vertices, l0.vertices)
 
+    # non-overlapping (gh-8848)
+    for overlap in (False, True):
+        grow_labels('fsaverage', [0], 1, 1, subjects_dir, overlap=overlap)
+
 
 @testing.requires_testing_data
 def test_random_parcellation():