Merge pull request #32 from graphgeeks-lab/gf-31

31: Graph Export Feature to GraphML

Author: denironyx

graphfaker/cli.py

@@ -50,15 +50,19 @@ def gen(
         None,
         help="Year, Month and day range (YYYY-MM-DD,YYYY-MM-DD) for flight data. e.g. '2024-01-01,2024-01-15'.",
     ),
+
+    # common
+    export: str = typer.Option("graph.graphml", help="File path to export GraphML"),
 ):
     """Generate a graph using GraphFaker."""
     gf = GraphFaker()
 
     if fetcher == FetcherType.FAKER:
 
         g = gf.generate_graph(total_nodes=total_nodes, total_edges=total_edges)
-        print(g)
-        return g
+        logger.info(
+            f"Generated random graph with {g.number_of_nodes()} nodes and {g.number_of_edges()} edges."
+        )
 
     elif fetcher == FetcherType.OSM:
         # parse bbox string if provided
@@ -75,8 +79,9 @@ def gen(
             retain_all=retain_all,
             dist=dist,
         )
-        print(g)
-        return g
+        logger.info(
+            f"Fetched OSM graph with {g.number_of_nodes()} nodes and {g.number_of_edges()} edges."
+        )
     else:
         # Flight fetcher
         parsed_date_range = parse_date_range(date_range) if date_range else None
@@ -101,8 +106,13 @@ def gen(
         )
 
         g = FlightGraphFetcher.build_graph(airlines_df, airports_df, flights_df)
-        print(g)
-        return g
+        
+        logger.info(
+            f"Generated flight graph with {g.number_of_nodes()} nodes and {g.number_of_edges()} edges."
+        )
+    
+    gf.export_graph(g, export)
+    logger.info(f"exported graph to {export}, with {g.number_of_nodes()} nodes and {g.number_of_edges()} edges.")
 
 
 if __name__ == "__main__":

graphfaker/core.py

@@ -2,6 +2,7 @@
 A multi-domain network connecting entities across social, geographical, and commercial dimensions.
 """
 
+import os
 from typing import Optional
 import networkx as nx
 import random
@@ -318,3 +319,35 @@ def generate_graph(
             )
         else:
             raise ValueError(f"Unknown source '{source}'. Use 'random' or 'osm'.")
+
+    def export_graph(self, G: nx.Graph = None, path: str = "graph.graphml"):
+        """
+        Export the graph to a GraphML format.
+
+        args:
+            G: Optional Networkx graph. If None, uses self.G.
+            path: Destination file path for .graphml output.
+        
+        Notes:
+            GraphML is useful for visualization in tools like G.V(), Gephi or Cytoscape.
+            It supports node and edge attributes but may not handle complex types like tuples.
+        """
+        import os
+
+        if G is None:
+            G = self.G
+        if G is None:
+            raise ValueError("No graph available to export.")
+        
+        # Sanitize attributes that are not GraphML-friendly
+        for _, data in G.nodes(data=True):
+            if 'coordinates' in data and isinstance(data['coordinates'], tuple):
+                lat, lon = data['coordinates']
+                data['coordinates'] = f"{lat},{lon}"
+
+        # Ensure directory exists
+        abs_path = os.path.abspath(path)
+        os.makedirs(os.path.dirname(abs_path) or ".", exist_ok=True)
+
+        nx.write_graphml(G, path)
+        print(f"✅ Graph exported to: {path}")