replace model with random in AgentSet init (#2350)

* replace model with random in AgentSet `__init__`

also closing #2323

mesa/agent.py

@@ -99,14 +99,18 @@ class AgentSet(MutableSet, Sequence):
         which means that agents not referenced elsewhere in the program may be automatically removed from the AgentSet.
     """
 
-    def __init__(self, agents: Iterable[Agent], model: Model):
+    def __init__(self, agents: Iterable[Agent], random: Random | None = None):
         """Initializes the AgentSet with a collection of agents and a reference to the model.
 
         Args:
             agents (Iterable[Agent]): An iterable of Agent objects to be included in the set.
-            model (Model): The ABM model instance to which this AgentSet belongs.
+            random (Random): the random number generator
         """
-        self.model = model
+        if random is None:
+            random = (
+                Random()
+            )  # FIXME see issue 1981, how to get the central rng from model
+        self.random = random
         self._agents = weakref.WeakKeyDictionary({agent: None for agent in agents})
 
     def __len__(self) -> int:
@@ -177,7 +181,7 @@ def agent_generator(filter_func, agent_type, at_most):
 
         agents = agent_generator(filter_func, agent_type, at_most)
 
-        return AgentSet(agents, self.model) if not inplace else self._update(agents)
+        return AgentSet(agents, self.random) if not inplace else self._update(agents)
 
     def shuffle(self, inplace: bool = False) -> AgentSet:
         """Randomly shuffle the order of agents in the AgentSet.
@@ -200,7 +204,7 @@ def shuffle(self, inplace: bool = False) -> AgentSet:
             return self
         else:
             return AgentSet(
-                (agent for ref in weakrefs if (agent := ref()) is not None), self.model
+                (agent for ref in weakrefs if (agent := ref()) is not None), self.random
             )
 
     def sort(
@@ -225,7 +229,7 @@ def sort(
         sorted_agents = sorted(self._agents.keys(), key=key, reverse=not ascending)
 
         return (
-            AgentSet(sorted_agents, self.model)
+            AgentSet(sorted_agents, self.random)
             if not inplace
             else self._update(sorted_agents)
         )
@@ -477,26 +481,17 @@ def __getstate__(self):
         Returns:
             dict: A dictionary representing the state of the AgentSet.
         """
-        return {"agents": list(self._agents.keys()), "model": self.model}
+        return {"agents": list(self._agents.keys()), "random": self.random}
 
     def __setstate__(self, state):
         """Set the state of the AgentSet during deserialization.
 
         Args:
             state (dict): A dictionary representing the state to restore.
         """
-        self.model = state["model"]
+        self.random = state["random"]
         self._update(state["agents"])
 
-    @property
-    def random(self) -> Random:
-        """Provide access to the model's random number generator.
-
-        Returns:
-            Random: The random number generator associated with the model.
-        """
-        return self.model.random
-
     def groupby(self, by: Callable | str, result_type: str = "agentset") -> GroupBy:
         """Group agents by the specified attribute or return from the callable.
 
@@ -529,7 +524,7 @@ def groupby(self, by: Callable | str, result_type: str = "agentset") -> GroupBy:
 
         if result_type == "agentset":
             return GroupBy(
-                {k: AgentSet(v, model=self.model) for k, v in groups.items()}
+                {k: AgentSet(v, random=self.random) for k, v in groups.items()}
             )
         else:
             return GroupBy(groups)

mesa/model.py

@@ -52,8 +52,6 @@ def __init__(self, *args: Any, seed: float | None = None, **kwargs: Any) -> None
         self.running = True
         self.steps: int = 0
 
-        self._setup_agent_registration()
-
         self._seed = seed
         if self._seed is None:
             # We explicitly specify the seed here so that we know its value in
@@ -65,6 +63,9 @@ def __init__(self, *args: Any, seed: float | None = None, **kwargs: Any) -> None
         self._user_step = self.step
         self.step = self._wrapped_step
 
+        # setup agent registration data structures
+        self._setup_agent_registration()
+
     def _wrapped_step(self, *args: Any, **kwargs: Any) -> None:
         """Automatically increments time and steps after calling the user's step method."""
         # Automatically increment time and step counters
@@ -119,7 +120,9 @@ def _setup_agent_registration(self):
         self._agents_by_type: dict[
             type[Agent], AgentSet
         ] = {}  # a dict with an agentset for each class of agents
-        self._all_agents = AgentSet([], self)  # an agenset with all agents
+        self._all_agents = AgentSet(
+            [], random=self.random
+        )  # an agenset with all agents
 
     def register_agent(self, agent):
         """Register the agent with the model.
@@ -153,7 +156,7 @@ def register_agent(self, agent):
                 [
                     agent,
                 ],
-                self,
+                random=self.random,
             )
 
         self._all_agents.add(agent)

tests/test_agent.py

@@ -62,7 +62,7 @@ def test_agentset():
     model = Model()
     agents = [AgentTest(model) for _ in range(10)]
 
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     assert agents[0] in agentset
     assert len(agentset) == len(agents)
@@ -118,7 +118,7 @@ def test_function(agent):
 
     # because AgentSet uses weakrefs, we need hard refs as well....
     other_agents, another_set = pickle.loads(  # noqa: S301
-        pickle.dumps([agents, AgentSet(agents, model)])
+        pickle.dumps([agents, AgentSet(agents, random=model.random)])
     )
     assert all(
         a1.unique_id == a2.unique_id for a1, a2 in zip(another_set, other_agents)
@@ -129,19 +129,19 @@ def test_function(agent):
 def test_agentset_initialization():
     """Test agentset initialization."""
     model = Model()
-    empty_agentset = AgentSet([], model)
+    empty_agentset = AgentSet([], random=model.random)
     assert len(empty_agentset) == 0
 
     agents = [AgentTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
     assert len(agentset) == 10
 
 
 def test_agentset_serialization():
     """Test pickleability of agentset."""
     model = Model()
     agents = [AgentTest(model) for _ in range(5)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     serialized = pickle.dumps(agentset)
     deserialized = pickle.loads(serialized)  # noqa: S301
@@ -156,7 +156,7 @@ def test_agent_membership():
     """Test agent membership in AgentSet."""
     model = Model()
     agents = [AgentTest(model) for _ in range(5)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     assert agents[0] in agentset
     assert AgentTest(model) not in agentset
@@ -166,7 +166,7 @@ def test_agent_add_remove_discard():
     """Test adding, removing and discarding agents from AgentSet."""
     model = Model()
     agent = AgentTest(model)
-    agentset = AgentSet([], model)
+    agentset = AgentSet([], random=model.random)
 
     agentset.add(agent)
     assert agent in agentset
@@ -186,7 +186,7 @@ def test_agentset_get_item():
     """Test integer based access to AgentSet."""
     model = Model()
     agents = [AgentTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     assert agentset[0] == agents[0]
     assert agentset[-1] == agents[-1]
@@ -200,7 +200,7 @@ def test_agentset_do_str():
     """Test AgentSet.do with str."""
     model = Model()
     agents = [AgentTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     with pytest.raises(AttributeError):
         agentset.do("non_existing_method")
@@ -213,7 +213,7 @@ def test_agentset_do_str():
     n = 10
     model = Model()
     agents = [AgentDoTest(model) for _ in range(n)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
     for agent in agents:
         agent.agent_set = agentset
 
@@ -223,7 +223,7 @@ def test_agentset_do_str():
     # setup
     model = Model()
     agents = [AgentDoTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
     for agent in agents:
         agent.agent_set = agentset
 
@@ -235,7 +235,7 @@ def test_agentset_do_callable():
     """Test AgentSet.do with callable."""
     model = Model()
     agents = [AgentTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     # Test callable with non-existent function
     with pytest.raises(AttributeError):
@@ -249,7 +249,7 @@ def test_agentset_do_callable():
     n = 10
     model = Model()
     agents = [AgentDoTest(model) for _ in range(n)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
     for agent in agents:
         agent.agent_set = agentset
 
@@ -260,7 +260,7 @@ def test_agentset_do_callable():
     # setup again for lambda function tests
     model = Model()
     agents = [AgentDoTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
     for agent in agents:
         agent.agent_set = agentset
 
@@ -278,7 +278,7 @@ def remove_function(agent):
     # setup again for actual function tests
     model = Model()
     agents = [AgentDoTest(model) for _ in range(n)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
     for agent in agents:
         agent.agent_set = agentset
 
@@ -289,7 +289,7 @@ def remove_function(agent):
     # setup again for actual function tests
     model = Model()
     agents = [AgentDoTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
     for agent in agents:
         agent.agent_set = agentset
 
@@ -354,7 +354,7 @@ def test_agentset_agg():
         agent.energy = i + 1
         agent.wealth = 10 * (i + 1)
 
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     # Test min aggregation
     min_energy = agentset.agg("energy", min)
@@ -391,7 +391,7 @@ def __init__(self, model, age=None):
 
     model = Model()
     agents = [TestAgentWithAttribute(model, age=i) for i in range(5)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     # Set a new attribute "health" and an existing attribute "age" for all agents
     agentset.set("health", 100).set("age", 50).set("status", "active")
@@ -410,7 +410,7 @@ def test_agentset_map_str():
     """Test AgentSet.map with strings."""
     model = Model()
     agents = [AgentTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     with pytest.raises(AttributeError):
         agentset.do("non_existing_method")
@@ -423,7 +423,7 @@ def test_agentset_map_callable():
     """Test AgentSet.map with callable."""
     model = Model()
     agents = [AgentTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     # Test callable with non-existent function
     with pytest.raises(AttributeError):
@@ -450,7 +450,7 @@ def test_method(self):
             self.called = True
 
     agents = [TestAgentShuffleDo(model) for _ in range(100)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     # Test shuffle_do with a string method name
     agentset.shuffle_do("test_method")
@@ -477,7 +477,7 @@ def test_agentset_get_attribute():
     """Test AgentSet.get for attributes."""
     model = Model()
     agents = [AgentTest(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     unique_ids = agentset.get("unique_id")
     assert unique_ids == [agent.unique_id for agent in agents]
@@ -491,7 +491,7 @@ def test_agentset_get_attribute():
         agent = AgentTest(model)
         agent.i = i**2
         agents.append(agent)
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     values = agentset.get(["unique_id", "i"])
 
@@ -521,7 +521,7 @@ def test_agentset_select_by_type():
 
     # Combine the two types of agents
     mixed_agents = test_agents + other_agents
-    agentset = AgentSet(mixed_agents, model)
+    agentset = AgentSet(mixed_agents, random=model.random)
 
     # Test selection by type
     selected_test_agents = agentset.select(agent_type=AgentTest)
@@ -544,11 +544,11 @@ def test_agentset_shuffle():
     model = Model()
     test_agents = [AgentTest(model) for _ in range(12)]
 
-    agentset = AgentSet(test_agents, model=model)
+    agentset = AgentSet(test_agents, random=model.random)
     agentset = agentset.shuffle()
     assert not all(a1 == a2 for a1, a2 in zip(test_agents, agentset))
 
-    agentset = AgentSet(test_agents, model=model)
+    agentset = AgentSet(test_agents, random=model.random)
     agentset.shuffle(inplace=True)
     assert not all(a1 == a2 for a1, a2 in zip(test_agents, agentset))
 
@@ -567,7 +567,7 @@ def get_unique_identifier(self):
 
     model = Model()
     agents = [TestAgent(model) for _ in range(10)]
-    agentset = AgentSet(agents, model)
+    agentset = AgentSet(agents, random=model.random)
 
     groups = agentset.groupby("even")
     assert len(groups.groups[True]) == 5