support strings in elements.get_node_id() (#522)

momepy/elements.py

@@ -804,8 +804,8 @@ def get_node_id(
             total=objects.shape[0],
             disable=not verbose,
         ):
-            if np.isnan(eid):
-                results_list.append(np.nan)
+            if pd.isna(eid):
+                results_list.append(pd.NA)
             else:
                 edge = edges.loc[eid]
                 start_id = edge.node_start

momepy/tests/test_elements.py

@@ -3,6 +3,7 @@
 
 import geopandas as gpd
 import numpy as np
+import pandas as pd
 import pytest
 from geopandas.testing import assert_geodataframe_equal
 from packaging.version import Version
@@ -154,8 +155,17 @@ def test_get_node_id(self):
         self.df_buildings["nID"] = mm.get_network_id(
             self.df_buildings, self.df_streets, "nID"
         )
-        ids = mm.get_node_id(self.df_buildings, nodes, edges, "nodeID", "nID")
-        assert not ids.isna().any()
+        ids1 = mm.get_node_id(self.df_buildings, nodes, edges, "nodeID", "nID")
+        assert not ids1.isna().any()
+
+        # test for NaNs within `object` nIDs column
+        edges["nID"] = edges["nID"].astype(str)
+        _df_buildings = self.df_buildings.copy()
+        _df_buildings["nID"] = _df_buildings["nID"].astype(str)
+        _df_buildings.loc[[0, 1], "nID"] = pd.NA
+        ids2 = mm.get_node_id(_df_buildings, nodes, edges, "nodeID", "nID")
+        assert ids2.isna().sum() == 2
+        np.testing.assert_array_equal(ids2[ids2.isna()].index, [0, 1])
 
     def test_get_node_id_ratio(self):
         nx = mm.gdf_to_nx(self.df_streets)