Update app.py

app.py

@@ -1,12 +1,90 @@
 import mesa
 
+def compute_gini(model):
+    agent_wealths = [agent.wealth for agent in model.schedule.agents]
+    x = sorted(agent_wealths)
+    N = model.num_agents
+    B = sum(xi * (N - i) for i, xi in enumerate(x)) / (N * sum(x))
+    return 1 + (1 / N) - 2 * B
+    
+    
+class MoneyAgent(mesa.Agent):
+    """An agent with fixed initial wealth."""
 
+    def __init__(self, unique_id, model):
+        super().__init__(unique_id, model)
+        self.wealth = 1
+
+    def move(self):
+        possible_steps = self.model.grid.get_neighborhood(
+            self.pos, moore=True, include_center=False
+        )
+        new_position = self.random.choice(possible_steps)
+        self.model.grid.move_agent(self, new_position)
+
+    def give_money(self):
+        cellmates = self.model.grid.get_cell_list_contents([self.pos])
+        if len(cellmates) > 1:
+            other_agent = self.random.choice(cellmates)
+            other_agent.wealth += 1
+            self.wealth -= 1
+
+    def step(self):
+        self.move()
+        if self.wealth > 0:
+            self.give_money()
+
+
+class MoneyModel(mesa.Model):
+    """A model with some number of agents."""
+
+    def __init__(self, N, width, height):
+        self.num_agents = N
+        self.grid = mesa.space.MultiGrid(width, height, True)
+        self.schedule = mesa.time.RandomActivation(self)
+        # Create agents
+        for i in range(self.num_agents):
+            a = MoneyAgent(i, self)
+            self.schedule.add(a)
+            # Add the agent to a random grid cell
+            x = self.random.randrange(self.grid.width)
+            y = self.random.randrange(self.grid.height)
+            self.grid.place_agent(a, (x, y))
+
+    def step(self):
+        self.datacollector.collect(self)
+        self.schedule.step()
+        
 def agent_portrayal(agent):
-    portrayal = {
-        "Shape": "circle",
-        "Color": "red",
-        "Filled": "true",
-        "Layer": 0,
-        "r": 0.5,
-    }
-    return portrayal
+    portrayal = {"Shape": "circle",
+                 "Filled": "true",
+                 "r": 0.5}
+
+    if agent.wealth > 0:
+        portrayal["Color"] = "red"
+        portrayal["Layer"] = 0
+    else:
+        portrayal["Color"] = "grey"
+        portrayal["Layer"] = 1
+        portrayal["r"] = 0.2
+    return portrayal
+
+
+grid = mesa.visualization.CanvasGrid(agent_portrayal, 10, 10, 500, 500)
+server = mesa.visualization.ModularServer(
+    MoneyModel, [grid], "Money Model", {"N": 100, "width": 10, "height": 10}
+)
+
+chart = mesa.visualization.ChartModule([{"Label": "Gini",
+                      "Color": "Black"}],
+                    data_collector_name='datacollector')
+
+server = mesa.visualization.ModularServer(MoneyModel,
+                       [grid, chart],
+                       "Money Model",
+                       {"N":100, "width":10, "height":10})
+                       
+server.port = 7860
+
+if __name__ == "__main__":
+    server.launch()