Remove exclude_none_values

This feature is functional only if the agent records are in the form of
```
{'satisfication': (('A0', 1), ('B0', None), ('A1', 1), ('B1', None), ('A2', 1), ('B2', None)), 'unique_id': (('A0', 'A0'), ('B0', 'B0'), ('A1', 'A1'), ('B1', 'B1'), ('A2', 'A2'), ('B2', 'B2'))}
```

instead of
```
((1, 'A0', 1, 'A0'), (1, 'B0', None, 'B0'), (1, 'A1', 1, 'A1'), (1, 'B1', None, 'B1'), (1, 'A2', 1, 'A2'), (1, 'B2', None, 'B2'))
```

A more explicit solution instead of implicitly ignoring a group of
agents just because of their attribute returns `None`, would be to add a
filter to the data collector itself. i.e., instead of
```python
agent_records = map(get_reports, model.schedule.agents)
```

we should do
```python
agent_records = map(get_reports, filter(agent_filter, model.schedule.agents))
```
Where `agent_filter` can be `lambda a: isinstance(a, Trader)`
. And this, too, is only a few lines of code of change.

mesa/datacollection.py

@@ -55,7 +55,6 @@ def __init__(
         model_reporters=None,
         agent_reporters=None,
         tables=None,
-        exclude_none_values=False,
     ):
         """Instantiate a DataCollector with lists of model and agent reporters.
         Both model_reporters and agent_reporters accept a dictionary mapping a
@@ -79,8 +78,6 @@ def __init__(
             model_reporters: Dictionary of reporter names and attributes/funcs
             agent_reporters: Dictionary of reporter names and attributes/funcs.
             tables: Dictionary of table names to lists of column names.
-            exclude_none_values: Boolean of whether to drop records which values
-            are None, in the final result.
 
         Notes:
             If you want to pickle your model you must not use lambda functions.
@@ -104,7 +101,6 @@ class attributes of a model
         self.model_vars = {}
         self._agent_records = {}
         self.tables = {}
-        self.exclude_none_values = exclude_none_values
 
         if model_reporters is not None:
             for name, reporter in model_reporters.items():
@@ -159,20 +155,6 @@ def _new_table(self, table_name, table_columns):
     def _record_agents(self, model):
         """Record agents data in a mapping of functions and agents."""
         rep_funcs = self.agent_reporters.values()
-        if self.exclude_none_values:
-            # Drop records which values are None.
-
-            def get_reports(agent):
-                _prefix = (agent.model.schedule.steps, agent.unique_id)
-                reports = (rep(agent) for rep in rep_funcs)
-                reports_without_none = tuple(r for r in reports if r is not None)
-                if len(reports_without_none) == 0:
-                    return None
-                return _prefix + reports_without_none
-
-            agent_records = (get_reports(agent) for agent in model.schedule.agents)
-            agent_records_without_none = (r for r in agent_records if r is not None)
-            return agent_records_without_none
 
         def get_reports(agent):
             _prefix = (agent.model.schedule.steps, agent.unique_id)

mesa/model.py

@@ -70,7 +70,6 @@ def initialize_data_collector(
         model_reporters=None,
         agent_reporters=None,
         tables=None,
-        exclude_none_values=False,
     ) -> None:
         if not hasattr(self, "schedule") or self.schedule is None:
             raise RuntimeError(
@@ -84,7 +83,6 @@ def initialize_data_collector(
             model_reporters=model_reporters,
             agent_reporters=agent_reporters,
             tables=tables,
-            exclude_none_values=exclude_none_values,
         )
         # Collect data for the first time during initialization.
         self.datacollector.collect(self)

tests/test_datacollector.py

@@ -47,20 +47,14 @@ class MockModel(Model):
 
     schedule = BaseScheduler(None)
 
-    def __init__(self, test_exclude_none_values=False):
+    def __init__(self):
         self.schedule = BaseScheduler(self)
         self.model_val = 100
 
         self.n = 10
         for i in range(self.n):
             self.schedule.add(MockAgent(i, self, val=i))
-            if test_exclude_none_values:
-                self.schedule.add(DifferentMockAgent(self.n + i, self, val=i))
-        if test_exclude_none_values:
-            # Only DifferentMockAgent has val3.
-            agent_reporters = {"value": lambda a: a.val, "value3": "val3"}
-        else:
-            agent_reporters = {"value": lambda a: a.val, "value2": "val2"}
+        agent_reporters = {"value": lambda a: a.val, "value2": "val2"}
         self.initialize_data_collector(
             {
                 "total_agents": lambda m: m.schedule.get_agent_count(),
@@ -71,7 +65,6 @@ def __init__(self, test_exclude_none_values=False):
             },
             agent_reporters,
             {"Final_Values": ["agent_id", "final_value"]},
-            exclude_none_values=test_exclude_none_values,
         )
 
     def test_model_calc_comp(self, input1, input2):
@@ -211,44 +204,5 @@ def test_initialize_before_agents_added_to_scheduler(self):
         )
 
 
-class TestDataCollectorExcludeNone(unittest.TestCase):
-    def setUp(self):
-        """
-        Create the model and run it a set number of steps.
-        """
-        self.model = MockModel(test_exclude_none_values=True)
-        for i in range(7):
-            if i == 4:
-                self.model.schedule.remove(self.model.schedule._agents[3])
-            self.model.step()
-
-    def test_agent_records(self):
-        """
-        Test agent-level variable collection.
-        """
-        data_collector = self.model.datacollector
-        agent_table = data_collector.get_agent_vars_dataframe()
-
-        assert len(data_collector._agent_records) == 8
-        for step, records in data_collector._agent_records.items():
-            if step < 5:
-                assert len(records) == 20
-            else:
-                assert len(records) == 19
-
-            for values in records:
-                agent_id = values[1]
-                if agent_id < self.model.n:
-                    assert len(values) == 3
-                else:
-                    # Agents with agent_id >= self.model.n are
-                    # DifferentMockAgent, which additionally contains val3.
-                    assert len(values) == 4
-
-        assert "value" in list(agent_table.columns)
-        assert "value2" not in list(agent_table.columns)
-        assert "value3" in list(agent_table.columns)
-
-
 if __name__ == "__main__":
     unittest.main()