ENH: do not fail with 3d nodes - preprocess.remove_false_nodes() (#661

)

* graceful failure with 3d nodes - remove_false_nodes()

* martin comments

* Update momepy/preprocessing.py

Co-authored-by: Martin Fleischmann <martin@martinfleischmann.net>

* re-leint

---------

Co-authored-by: Martin Fleischmann <martin@martinfleischmann.net>

momepy/preprocessing.py

@@ -166,8 +166,8 @@ def preprocess(
 def remove_false_nodes(gdf):
     """
     Clean topology of existing LineString geometry by removal of nodes of degree 2.
-
-    Returns the original gdf if there's no node of degree 2.
+    Returns the original gdf if there's no node of degree 2. Some geometries may
+    be forced to 2D where a Z coordinate is present.
 
     Parameters
     ----------
@@ -178,7 +178,7 @@ def remove_false_nodes(gdf):
     -------
     gdf : GeoDataFrame, GeoSeries
 
-    See also
+    See Also
     --------
     momepy.extend_lines
     momepy.close_gaps
@@ -247,14 +247,16 @@ def remove_false_nodes(gdf):
             ),
             lines=False,
         )
+
         loops = combined[combined.is_ring]
+
         node_ix, loop_ix = loops.sindex.query(nodes.geometry, predicate="intersects")
         for ix in np.unique(loop_ix):
             loop_geom = loops.geometry.iloc[ix]
             target_nodes = nodes.geometry.iloc[node_ix[loop_ix == ix]]
             if len(target_nodes) == 2:
                 node_coords = shapely.get_coordinates(target_nodes)
-                coords = np.array(loop_geom.coords)
+                coords = shapely.get_coordinates(loop_geom)
                 new_start = (
                     node_coords[0]
                     if (node_coords[0] != coords[0]).all()

momepy/tests/test_preprocess.py

@@ -2,7 +2,7 @@
 import numpy as np
 import pytest
 from geopandas.testing import assert_geodataframe_equal
-from shapely import affinity
+from shapely import affinity, force_3d
 from shapely.geometry import LineString, MultiPoint, Point, Polygon
 from shapely.ops import polygonize
 
@@ -67,6 +67,16 @@ def test_remove_false_nodes(self):
         df = self.df_streets.drop([4, 7, 17, 22])
         assert_geodataframe_equal(df, mm.remove_false_nodes(df))
 
+        # check 3d coords in loop
+        line_1 = LineString((Point(1, 1), Point(2, 2)))
+        line_2 = LineString((Point(2, 2), Point(3, 3)))
+        line_3 = force_3d(LineString((Point(2, 2), Point(1, 2))))
+        line_4 = LineString((Point(1, 2), Point(1, 3)))
+        line_5 = LineString((Point(1, 3), Point(2, 2)))
+        with_3d = np.array([line_1, line_2, line_3, line_4, line_5])
+        no_3d = mm.remove_false_nodes(with_3d)
+        assert len(no_3d) == 3
+
     def test_CheckTessellationInput(self):
         df = self.df_buildings
         df.loc[144, "geometry"] = Polygon([(0, 0), (0, 1), (1, 0)])