Fix slow DataFrame creation in CogniteResource.to_pandas (#1389)

cognite/client/data_classes/_base.py

@@ -164,10 +164,8 @@ def to_pandas(
                     dumped.update(dumped.pop(key))
                 else:
                     raise AssertionError(f"Could not expand attribute '{key}'")
-        df = pd.DataFrame(columns=["value"])
-        for name, value in dumped.items():
-            df.loc[name] = [value]
-        return df
+
+        return pd.Series(dumped).to_frame(name="value")
 
     def _repr_html_(self) -> str:
         return notebook_display_with_fallback(self)

tests/tests_unit/test_base.py

@@ -370,6 +370,41 @@ def test_use_method_which_requires_cognite_client__client_not_set(self):
         with pytest.raises(CogniteMissingClientError):
             mr.use()
 
+    @pytest.mark.dsl
+    def test_to_pandas_method(self):
+        import pandas as pd
+
+        from cognite.client.data_classes import Asset, Label
+
+        asset = Asset(
+            external_id="test-1",
+            name="test 1",
+            parent_external_id="parent-test-1",
+            description="A test asset",
+            data_set_id=123,
+            labels=[Label(external_id="ROTATING_EQUIPMENT", name="Rotating equipment")],
+        )
+
+        result_df = asset.to_pandas()
+
+        data = {
+            "value": [
+                "test-1",
+                "test 1",
+                "parent-test-1",
+                "A test asset",
+                123,
+                [{"externalId": "ROTATING_EQUIPMENT", "name": "Rotating equipment"}],
+            ]
+        }
+
+        index_labels = ["external_id", "name", "parent_external_id", "description", "data_set_id", "labels"]
+
+        expected_df = pd.DataFrame(data, index=index_labels)
+
+        # Assert that the resultant DataFrame is equal to the expected DataFrame
+        pd.testing.assert_frame_equal(result_df, expected_df)
+
 
 class TestCogniteFilter:
     def test_dump(self):