Update app.py

app.py

@@ -86,7 +86,8 @@ def display_simple_graph(G, pos=None, directed=False):
         "linewidths": 5,
         "width": 5,
     }
-
+    
+    # Draw the network
     if directed:
         nx.draw_networkx(G, pos, **options, arrows=True)  # For directed graph with arrows
     else:
@@ -145,8 +146,22 @@ elif sidebar_option == "Basic: Simple graph":
     st.title("Basic: Simple graph")
     option = st.radio("Choose a graph type:", ("Default Example", "Create your own"))
 
-    # Default example: directed graph with custom positions
+    # Default example: simple undirected graph
     if option == "Default Example":
+        G = nx.Graph()
+        G.add_edge(1, 2)
+        G.add_edge(1, 3)
+        G.add_edge(1, 5)
+        G.add_edge(2, 3)
+        G.add_edge(3, 4)
+        G.add_edge(4, 5)
+
+        # explicitly set positions for visualization
+        pos = {1: (0, 0), 2: (-1, 0.3), 3: (2, 0.17), 4: (4, 0.255), 5: (5, 0.03)}
+        display_simple_graph(G, pos)
+
+    # Default example: directed graph with custom positions (added the missing part)
+    if option == "Default Example" and st.session_state.graph_displayed == False:
         G = nx.DiGraph([(0, 3), (1, 3), (2, 4), (3, 5), (3, 6), (4, 6), (5, 6)])
 
         # Group nodes by column
@@ -159,8 +174,10 @@ elif sidebar_option == "Basic: Simple graph":
         pos.update({n: (1, i + 0.5) for i, n in enumerate(middle_nodes)})
         pos.update({n: (2, i + 0.5) for i, n in enumerate(right_nodes)})
 
+        # Visualize the directed graph
         display_simple_graph(G, pos, directed=True)
-
+        st.session_state.graph_displayed = True
+        
     # Create your own graph
     elif option == "Create your own":
         num_nodes = st.number_input("Number of nodes:", min_value=2, max_value=20, value=5)
@@ -179,9 +196,9 @@ elif sidebar_option == "Basic: Simple graph":
 
         # Button to generate the graph
         if st.button("Generate"):
-            G_custom = nx.DiGraph()  # Directed graph
+            G_custom = nx.Graph()
             G_custom.add_edges_from(edges)
             
             # Set a basic layout (spring layout as default)
             pos = nx.spring_layout(G_custom, seed=42)
-            display_simple_graph(G_custom, pos, directed=True)
+            display_simple_graph(G_custom, pos)