Always ravel array in unique_array

holoviews/core/util.py

@@ -1218,8 +1218,10 @@ def unique_array(arr):
         if (isinstance(v, datetime_types) and
             not isinstance(v, cftime_types)):
             v = pd.Timestamp(v).to_datetime64()
+        elif isinstance(getattr(v, "dtype", None), pd.CategoricalDtype):
+            v = v.dtype.categories
         values.append(v)
-    return pd.unique(np.asarray(values))
+    return pd.unique(np.asarray(values).ravel())
 
 
 def match_spec(element, specification):

holoviews/tests/core/test_utils.py

@@ -28,6 +28,7 @@
     sanitize_identifier_fn,
     search_indices,
     tree_attribute,
+    unique_array,
     wrap_tuple_streams,
 )
 from holoviews.element.comparison import ComparisonTestCase
@@ -799,3 +800,9 @@ def test_seach_indices_dtype_object():
     values = np.array(["c0", "c0", np.nan], dtype=object)
     source = np.array(["c0", np.nan], dtype=object)
     search_indices(values, source)
+
+
+def test_unique_array_categorial():
+    ser = pd.Series(np.random.choice(["a", "b", "c"], 100)).astype("category")
+    res = unique_array([ser])
+    assert sorted(res) == ["a", "b", "c"]

pyproject.toml

@@ -102,6 +102,6 @@ known-first-party = ["holoviews"]
 combine-as-imports = true
 
 [tool.codespell]
-ignore-words-list = "lod,nd,ndoes,reenabled,spreaded,whn"
+ignore-words-list = "lod,nd,ndoes,reenabled,spreaded,whn,ser"
 skip = "doc/generate_modules.py"
 write-changes = true