move boltzman benchmark wealth model to new spaces

Author: quaquel

benchmarks/BoltzmannWealth/boltzmann_wealth.py

@@ -1,6 +1,6 @@
 # https://github.com/projectmesa/mesa-examples/blob/main/examples/boltzmann_wealth_model_experimental/model.py
 import mesa
-
+import mesa.spaces as spaces
 
 def compute_gini(model):
     agent_wealths = [agent.wealth for agent in model.agents]
@@ -21,18 +21,18 @@ class BoltzmannWealth(mesa.Model):
     def __init__(self, seed=None, n=100, width=10, height=10):
         super().__init__()
         self.num_agents = n
-        self.grid = mesa.space.MultiGrid(width, height, True)
+        self.grid = spaces.OrthogonalMooreGrid((width, height))
         self.schedule = mesa.time.RandomActivation(self)
         self.datacollector = mesa.DataCollector(
             model_reporters={"Gini": compute_gini}, agent_reporters={"Wealth": "wealth"}
         )
         # Create agents
         for _ in range(self.num_agents):
-            a = MoneyAgent(self)
+            agent = MoneyAgent(self)
             # 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))
+            x = self.random.randrange(width)
+            y = self.random.randrange(height)
+            agent.move_to(self.grid[(x, y)])
 
         self.running = True
         self.datacollector.collect(self)
@@ -47,31 +47,34 @@ def run_model(self, n):
             self.step()
 
 
-class MoneyAgent(mesa.Agent):
+class MoneyAgent(mesa.spaces.CellAgent):
     """An agent with fixed initial wealth."""
 
     def __init__(self, model):
         super().__init__(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 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])
-        cellmates.pop(
-            cellmates.index(self)
-        )  # Ensure agent is not giving money to itself
+        cellmates = [agent for agent in self.cell.agents if not agent is self]
         if len(cellmates) > 0:
             other = self.random.choice(cellmates)
             other.wealth += 1
             self.wealth -= 1
 
     def step(self):
-        self.move()
+        self.move_to(self.cell.neighborhood().select_random_cell())
         if self.wealth > 0:
             self.give_money()
+
+
+if __name__ == '__main__':
+    model = BoltzmannWealth()
+    for _ in range(10):
+        model.step()

mesa/spaces/cell.py

@@ -121,7 +121,9 @@ def __repr__(self):
 
     # FIXME: Revisit caching strategy on methods
     @cache  # noqa: B019
-    def neighborhood(self, radius=1, include_center=False):
+    def neighborhood(self, radius: int = 1, include_center: bool = False) -> CellCollection:
+        # FIXME? if this is a method rather than a property, should it not be get_neighborhood?
+        # FIXME:: operating on this has side effects!
         return CellCollection(
             self._neighborhood(radius=radius, include_center=include_center),
             random=self.random,

mesa/spaces/cell_agent.py

@@ -24,14 +24,16 @@ def __init__(self, model: Model) -> None:
         Create a new agent.
 
         Args:
-            unique_id (int): A unique identifier for this agent.
             model (Model): The model instance in which the agent exists.
         """
         super().__init__(model)
         self.cell: Cell | None = None
 
     def move_to(self, cell) -> None:
         if self.cell is not None:
-            self.cell.remove_agent(self)
+            try:
+                self.cell.remove_agent(self)
+            except ValueError:
+                raise ValueError("Cannot remove agent from cell")
         self.cell = cell
         cell.add_agent(self)