Make `trajectories` an attribute of Visitor

Instead of a global variable with hidden modification in a method of Visitor.

gt_matlab_trajs.py

@@ -22,11 +22,14 @@ from graph_tool import util, search
 import sys
 
 class Visitor(search.BFSVisitor):
+    def __init__(self):
+        self.trajectories = {}
+
     def discover_vertex(self, u):
-        if g.vp.traj[u] not in trajectories:
-            trajectories[g.vp.traj[u]] = [g.vp.name[u]]
+        if g.vp.traj[u] not in self.trajectories:
+            self.trajectories[g.vp.traj[u]] = [g.vp.name[u]]
         else:
-            trajectories[g.vp.traj[u]].append(g.vp.name[u])
+            self.trajectories[g.vp.traj[u]].append(g.vp.name[u])
 
 g = graph_tool.load_graph(sys.argv[1])
 g.vp['traj'] = g.new_vp('int')
@@ -65,17 +68,17 @@ print('Algorithm done, saving...')
 
 # Make a dictionary of trajectories:
 
-trajectories = {}
-search.bfs_search(g, visitor = Visitor())
+visitor = Visitor()
+search.bfs_search(g, visitor = visitor)
 
 with open("trajectories.json", "w") as outfile:
-    json.dump(trajectories, outfile, indent = 4)
+    json.dump(visitor.trajectories, outfile, indent = 4)
 
 # Setup a new trajectory that holds the expanded segments:
 
 expanded_trajectories = {}
 
-for trajectory in trajectories.values():
+for trajectory in visitor.trajectories.values():
     # Expand trajectory of current traj key = []
     key = trajectory[0]
     for val in trajectory:
@@ -98,4 +101,4 @@ for trajectory in trajectories.values():
 with open("expanded_trajectories.json", "w") as outfile:
     json.dump(expanded_trajectories, outfile, indent = 4)
 
-print(f'Done saving json: {len(trajectories)} trajectories.')
+print(f'Done saving json: {len(visitor.trajectories)} trajectories.')