Components: Switch from factory methods to prototype objects

miplearn/components/lazy_static.py

@@ -4,12 +4,12 @@
 
 import logging
 import sys
-from copy import deepcopy
-from typing import Any, Dict, Tuple, Optional
+from typing import Dict, Tuple, Optional
 
 import numpy as np
 from tqdm.auto import tqdm
 
+from miplearn import Classifier
 from miplearn.classifiers.counting import CountingClassifier
 from miplearn.components.component import Component
 from miplearn.types import TrainingSample, Features
@@ -32,6 +32,7 @@ class StaticLazyConstraintsComponent(Component):
         large_gap=1e-2,
         violation_tolerance=-0.5,
     ):
+        assert isinstance(classifier, Classifier)
         self.threshold = threshold
         self.classifier_prototype = classifier
         self.classifiers = {}
@@ -120,7 +121,7 @@ class StaticLazyConstraintsComponent(Component):
             x.keys(), desc="Fit (lazy)", disable=not sys.stdout.isatty()
         ):
             if category not in self.classifiers:
-                self.classifiers[category] = deepcopy(self.classifier_prototype)
+                self.classifiers[category] = self.classifier_prototype.clone()
             self.classifiers[category].fit(x[category], y[category])
 
     def predict(self, instance):