community[patch]: Added functions in NetworkxEntityGraph class (#17535)

- **Description:** 
1. Added _clear_edges()_ and _get_number_of_nodes()_ functions in
NetworkxEntityGraph class.
2. Added the above two function in graph_networkx_qa.ipynb
documentation.

docs/docs/use_cases/graph/graph_networkx_qa.ipynb

@@ -298,12 +298,34 @@
    "id": "045796cf",
    "metadata": {},
    "outputs": [],
-   "source": []
+   "source": [
+    "loaded_graph.get_number_of_nodes()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "d24b3407",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "loaded_graph.clear_edges()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "b8afda51",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "loaded_graph.clear()"
+   ]
   }
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3 (ipykernel)",
+   "display_name": "Python 3.10.6 64-bit",
    "language": "python",
    "name": "python3"
   },
@@ -317,7 +339,12 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.10.12"
+   "version": "3.10.6"
+  },
+  "vscode": {
+   "interpreter": {
+    "hash": "aee8b7b246df8f9039afb4144a1f6fd8d2ca17a180786b69acc140d282b71a49"
+   }
   }
  },
  "nbformat": 4,

libs/community/langchain_community/graphs/networkx_graph.py

@@ -135,6 +135,14 @@ class NetworkxEntityGraph:
         """Clear the graph."""
         self._graph.clear()
 
+    def clear_edges(self) -> None:
+        """Clear the graph edges."""
+        self._graph.clear_edges()
+
+    def get_number_of_nodes(self) -> int:
+        """Get number of nodes in the graph."""
+        return self._graph.number_of_nodes()
+
     def get_topological_sort(self) -> List[str]:
         """Get a list of entity names in the graph sorted by causal dependence."""
         import networkx as nx