Fix subgraph filtering bugs

lightrag/kg/networkx_impl.py

@@ -263,12 +263,14 @@ class NetworkXStorage(BaseGraphStorage):
 
         graph = await self._get_graph()
 
+        # Initialize sets for start nodes and direct connected nodes
+        start_nodes = set()
+        direct_connected_nodes = set()
+
         # Handle special case for "*" label
         if node_label == "*":
             # For "*", return the entire graph including all nodes and edges
-            subgraph = (
-                graph.copy()
-            )  # Create a copy to avoid modifying the original graph
+            subgraph = graph.copy()  # Create a copy to avoid modifying the original graph
         else:
             # Find nodes with matching node id based on search_mode
             nodes_to_explore = []
@@ -292,10 +294,7 @@ class NetworkXStorage(BaseGraphStorage):
                 combined_subgraph = nx.compose(combined_subgraph, node_subgraph)
 
             # Get start nodes and direct connected nodes
-            start_nodes = set()
-            direct_connected_nodes = set()
-
-            if node_label != "*" and nodes_to_explore:
+            if nodes_to_explore:
                 start_nodes = set(nodes_to_explore)
                 # Get nodes directly connected to all start nodes
                 for start_node in start_nodes:
@@ -306,19 +305,18 @@ class NetworkXStorage(BaseGraphStorage):
                 # Remove start nodes from directly connected nodes (avoid duplicates)
                 direct_connected_nodes -= start_nodes
 
-            # Filter nodes based on min_degree, but keep start nodes and direct connected nodes
-            if min_degree > 0:
-                nodes_to_keep = [
-                    node
-                    for node, degree in combined_subgraph.degree()
-                    if node in start_nodes
-                    or node in direct_connected_nodes
-                    or degree >= min_degree
-                ]
-                combined_subgraph = combined_subgraph.subgraph(nodes_to_keep)
-
             subgraph = combined_subgraph
 
+        # Filter nodes based on min_degree, but keep start nodes and direct connected nodes
+        if min_degree > 0:
+            nodes_to_keep = [
+                node
+                for node, degree in subgraph.degree()
+                if (node_label != "*" and (node in start_nodes or node in direct_connected_nodes))
+                or degree >= min_degree
+            ]
+            subgraph = subgraph.subgraph(nodes_to_keep)
+
         # Check if number of nodes exceeds max_graph_nodes
         if len(subgraph.nodes()) > MAX_GRAPH_NODES:
             origin_nodes = len(subgraph.nodes())