Propagate minR and maxR from scenario into intensifier (#775)

* Test propagation of minR and maxR from scenario into default intensifier

in SMAC4AC.

* Propagate intensifier kwargs from scenario to Intensifier in SMAC4AC

even when the intensifier class is not specified explicitly
and is defaulted to Intensifier.

* Clean up intensifier instantiation

- Only define `intensifier_def_kwargs` when needed.
- Remove a superfluous condition `isinstance(intensifier, Intensifier)`.

* Update documentation of argument `intensifier`

of `SMAC4AC.__init__`.

* Allow instantiating `SMAC4AC` with an intensifier object

The object must be an instance of `Intensifier`.

* Allow intensifier to be an instance of `AbstractRacer`

instead of requiring an instance of `Intensifier`.

* Document parameter `intensifier` in more detail

smac/facade/smac_ac_facade.py

@@ -124,9 +124,9 @@ def __init__(self,
             arguments passed to constructor of runhistory.
             We strongly advise against changing the aggregation function,
             since it will break some code assumptions
-        intensifier : Intensifier
-            intensification object to issue a racing to decide the current
-            incumbent
+        intensifier : AbstractRacer
+            intensification object or class to issue a racing to decide the current
+            incumbent. Default: class `Intensifier`
         intensifier_kwargs: Optional[Dict]
             arguments passed to the constructor of '~intensifier'
         acquisition_function : `~smac.optimizer.acquisition.AbstractAcquisitionFunction`
@@ -413,34 +413,35 @@ def __init__(self,
                              "the scenario must be the same, but are '%s' and "
                              "'%s'" % (tae_runner_instance.run_obj, scenario.run_obj))  # type: ignore[union-attr] # noqa F821
 
-        # initialize intensification
-        intensifier_def_kwargs = {
-            'stats': self.stats,
-            'traj_logger': traj_logger,
-            'rng': rng,
-            'instances': scenario.train_insts,  # type: ignore[attr-defined] # noqa F821
-            'cutoff': scenario.cutoff,  # type: ignore[attr-defined] # noqa F821
-            'deterministic': scenario.deterministic,  # type: ignore[attr-defined] # noqa F821
-            'run_obj_time': scenario.run_obj == "runtime",  # type: ignore[attr-defined] # noqa F821
-            'instance_specifics': scenario.instance_specific,  # type: ignore[attr-defined] # noqa F821
-            'adaptive_capping_slackfactor': scenario.intens_adaptive_capping_slackfactor,  # type: ignore[attr-defined] # noqa F821
-            'min_chall': scenario.intens_min_chall  # type: ignore[attr-defined] # noqa F821
-        }
-
-        if isinstance(intensifier, Intensifier) \
-                or (intensifier is not None and inspect.isclass(intensifier) and issubclass(intensifier, Intensifier)):
-            intensifier_def_kwargs['always_race_against'] = scenario.cs.get_default_configuration()  # type: ignore[attr-defined] # noqa F821
-            intensifier_def_kwargs['use_ta_time_bound'] = scenario.use_ta_time  # type: ignore[attr-defined] # noqa F821
-            intensifier_def_kwargs['minR'] = scenario.minR  # type: ignore[attr-defined] # noqa F821
-            intensifier_def_kwargs['maxR'] = scenario.maxR  # type: ignore[attr-defined] # noqa F821
-        if intensifier_kwargs is not None:
-            intensifier_def_kwargs.update(intensifier_kwargs)
-
         if intensifier is None:
-            intensifier_instance = (
-                Intensifier(**intensifier_def_kwargs)  # type: ignore[arg-type] # noqa F821
-            )  # type: AbstractRacer
+            intensifier = Intensifier
+
+        if isinstance(intensifier, AbstractRacer):
+            intensifier_instance = intensifier
         elif inspect.isclass(intensifier):
+            # initialize intensification
+            intensifier_def_kwargs = {
+                'stats': self.stats,
+                'traj_logger': traj_logger,
+                'rng': rng,
+                'instances': scenario.train_insts,  # type: ignore[attr-defined] # noqa F821
+                'cutoff': scenario.cutoff,  # type: ignore[attr-defined] # noqa F821
+                'deterministic': scenario.deterministic,  # type: ignore[attr-defined] # noqa F821
+                'run_obj_time': scenario.run_obj == "runtime",  # type: ignore[attr-defined] # noqa F821
+                'instance_specifics': scenario.instance_specific,  # type: ignore[attr-defined] # noqa F821
+                'adaptive_capping_slackfactor': scenario.intens_adaptive_capping_slackfactor,  # type: ignore[attr-defined] # noqa F821
+                'min_chall': scenario.intens_min_chall  # type: ignore[attr-defined] # noqa F821
+            }
+
+            if issubclass(intensifier, Intensifier):
+                intensifier_def_kwargs['always_race_against'] = scenario.cs.get_default_configuration()  # type: ignore[attr-defined] # noqa F821
+                intensifier_def_kwargs['use_ta_time_bound'] = scenario.use_ta_time  # type: ignore[attr-defined] # noqa F821
+                intensifier_def_kwargs['minR'] = scenario.minR  # type: ignore[attr-defined] # noqa F821
+                intensifier_def_kwargs['maxR'] = scenario.maxR  # type: ignore[attr-defined] # noqa F821
+
+            if intensifier_kwargs is not None:
+                intensifier_def_kwargs.update(intensifier_kwargs)
+
             intensifier_instance = intensifier(**intensifier_def_kwargs)  # type: ignore[arg-type] # noqa F821
         else:
             raise TypeError(

test/test_facade/test_smac_facade.py

@@ -41,8 +41,9 @@ class TestSMACFacade(unittest.TestCase):
 
     def setUp(self):
         self.cs = ConfigurationSpace()
-        self.scenario = Scenario({'cs': self.cs, 'run_obj': 'quality',
-                                  'output_dir': ''})
+        self.scenario_dict_default = {'cs': self.cs, 'run_obj': 'quality',
+                                      'output_dir': ''}
+        self.scenario = Scenario(self.scenario_dict_default)
         self.sh_intensifier_kwargs = {'n_seeds': 1,
                                       'initial_budget': 1,
                                       'eta': 3,
@@ -218,6 +219,18 @@ class DummyIntensifier(Intensifier):
         self.assertIsInstance(smbo.solver.intensifier, DummyIntensifier)
         self.assertEqual(smbo.solver.intensifier.maxR, 987)
 
+        # Assert that minR, maxR and use_ta_time propagate from scenario to the default intensifier.
+        for scenario_dict in [{}, {'minR': self.scenario.minR + 1, 'maxR': self.scenario.maxR + 1,
+                                   'use_ta_time': not self.scenario.use_ta_time}]:
+            for k, v in self.scenario_dict_default.items():
+                if k not in scenario_dict:
+                    scenario_dict[k] = v
+            scenario = Scenario(scenario_dict)
+            smac = SMAC4AC(scenario=scenario)
+            self.assertEqual(scenario.minR, smac.solver.intensifier.minR)
+            self.assertEqual(scenario.maxR, smac.solver.intensifier.maxR)
+            self.assertEqual(scenario.use_ta_time, smac.solver.intensifier.use_ta_time_bound)
+
     def test_construct_initial_design(self):
 
         rng = np.random.RandomState(42)