ENH: either support MultiIndex or raise an error when one is given

momepy/functional/_elements.py

@@ -10,7 +10,7 @@
 from libpysal.cg import voronoi_frames
 from libpysal.graph import Graph
 from packaging.version import Version
-from pandas import Series
+from pandas import MultiIndex, Series
 
 GPD_GE_013 = Version(gpd.__version__) >= Version("0.13.0")
 GPD_GE_10 = Version(gpd.__version__) >= Version("1.0dev")
@@ -103,6 +103,10 @@ def morphological_tessellation(
     4  POLYGON ((1603084.231 6464104.386, 1603083.773...
 
     """
+
+    if isinstance(geometry.index, MultiIndex):
+        raise ValueError("MultiIndex is not supported for tessellation.")
+
     if isinstance(clip, GeoSeries | GeoDataFrame):
         clip = clip.union_all() if GPD_GE_10 else clip.unary_union
 
@@ -218,6 +222,9 @@ def enclosed_tessellation(
     126  POLYGON ((1603528.593 6464221.033, 1603527.796...                0
     """
 
+    if isinstance(geometry.index, MultiIndex):
+        raise ValueError("MultiIndex is not supported for tessellation.")
+
     # convert to GeoDataFrame and add position (we will need it later)
     enclosures = enclosures.geometry.to_frame()
     enclosures["position"] = range(len(enclosures))
@@ -360,6 +367,12 @@ def verify_tessellation(tessellation, geometry):
 
     >>> excluded, multipolygons = momepy.verify_tessellation(tessellation, buildings)
     """
+
+    if isinstance(geometry.index, MultiIndex) or isinstance(
+        tessellation.index, MultiIndex
+    ):
+        raise ValueError("MultiIndex is not supported for tessellation.")
+
     # check against input layer
     ids_original = geometry.index
     ids_generated = tessellation.index
@@ -397,7 +410,7 @@ def get_nearest_street(
     buildings: GeoSeries | GeoDataFrame,
     streets: GeoSeries | GeoDataFrame,
     max_distance: float | None = None,
-) -> np.ndarray:
+) -> Series:
     """Identify the nearest street for each building.
 
     Parameters
@@ -447,12 +460,11 @@ def get_nearest_street(
     )
 
     if streets.index.dtype == "object":
-        ids = np.empty(len(buildings), dtype=object)
+        ids = pd.Series(None, index=buildings.index)
     else:
-        ids = np.empty(len(buildings), dtype=np.float32)
-        ids[:] = np.nan
+        ids = pd.Series(np.nan, index=buildings.index)
 
-    ids[blg_idx] = streets.index[str_idx]
+    ids.iloc[blg_idx] = streets.index[str_idx]
     return ids
 
 
@@ -522,6 +534,17 @@ def get_nearest_node(
     143    22.0
     Length: 144, dtype: float64
     """
+
+    if (
+        isinstance(buildings.index, MultiIndex)
+        or isinstance(nearest_edge.index, MultiIndex)
+        or isinstance(nodes.index, MultiIndex)
+        or isinstance(edges.index, MultiIndex)
+    ):
+        raise ValueError(
+            "MultiIndex is not supported for calculating the nearest node."
+        )
+
     # treat possibly missing edge index
     a = np.empty(len(buildings))
     na_mask = np.isnan(nearest_edge)
@@ -606,6 +629,12 @@ def generate_blocks(
     >>> tessellation["block_id"] = tessellation_id
     """
 
+    if (
+        isinstance(buildings.index, MultiIndex)
+        or isinstance(tessellation.index, MultiIndex)
+        or isinstance(edges.index, MultiIndex)
+    ):
+        raise ValueError("MultiIndex is not supported for generating blocks.")
     id_name: str = "bID"
 
     # slice the tessellations by the street network

momepy/functional/_shape.py

@@ -4,7 +4,7 @@
 from geopandas import GeoDataFrame, GeoSeries
 from numpy.typing import NDArray
 from packaging.version import Version
-from pandas import DataFrame, Series
+from pandas import DataFrame, MultiIndex, Series
 
 from momepy.functional import _dimension
 
@@ -724,6 +724,10 @@
             "momepy.centroid_corner_distance requires geopandas 0.13 or later. "
         )
 
+    result_index = geometry.index
+    if isinstance(geometry.index, MultiIndex):
+        geometry = geometry.reset_index(drop=True)
+
     def _ccd(points: DataFrame, eps: float) -> Series:
         centroid = points.values[0, 2:]
         pts = points.values[:-1, :2]
@@ -738,7 +742,7 @@
         coords = geometry.exterior.get_coordinates(index_parts=False)
     coords[["cent_x", "cent_y"]] = geometry.centroid.get_coordinates(index_parts=False)
     ccd = coords.groupby(level=0).apply(_ccd, eps=eps)
-    ccd.index = geometry.index
+    ccd.index = result_index
     return ccd
 
 

momepy/functional/tests/test_elements.py

@@ -222,7 +222,7 @@ def test_get_nearest_street(self):
 
         streets.index = streets.index.astype(str)
         nearest = mm.get_nearest_street(self.df_buildings, streets, 10)
-        assert (nearest == None).sum() == 137  # noqa: E711
+        assert pd.isna(nearest).sum() == 137  # noqa: E711
 
     def test_get_nearest_node(self):
         nodes, edges = mm.nx_to_gdf(mm.gdf_to_nx(self.df_streets))
@@ -332,6 +332,34 @@ def test_blocks_inner(self):
         else:
             assert len(blocks.sindex.query_bulk(blocks.geometry, "overlaps")[0]) == 0
 
+    def test_multi_index(self):
+        buildings = self.df_buildings.set_index(["uID", "uID"])
+        with pytest.raises(
+            ValueError, match="MultiIndex is not supported for tessellation."
+        ):
+            mm.morphological_tessellation(buildings)
+        with pytest.raises(
+            ValueError, match="MultiIndex is not supported for tessellation."
+        ):
+            mm.enclosed_tessellation(buildings, self.enclosures)
+        with pytest.raises(
+            ValueError, match="MultiIndex is not supported for tessellation."
+        ):
+            mm.verify_tessellation(buildings, self.enclosures)
+
+        with pytest.raises(
+            ValueError,
+            match="MultiIndex is not supported for calculating the nearest node.",
+        ):
+            mm.get_nearest_node(
+                buildings, self.enclosures, self.enclosures, self.enclosures
+            )
+
+        with pytest.raises(
+            ValueError, match="MultiIndex is not supported for generating blocks."
+        ):
+            mm.generate_blocks(buildings, self.enclosures, self.enclosures)
+
     def test_tess_single_building_edge_case(self):
         tessellations = mm.enclosed_tessellation(
             self.df_buildings, self.enclosures.geometry, n_jobs=-1