evaluators can now be str or function

src/menelaus/ensemble.py

@@ -150,10 +150,11 @@ class Ensemble:
     def __init__(self, detectors: dict, evaluator, columns: dict = None):
         self.detectors = detectors.copy()
         self.columns = columns
-        # XXX - Since rigid type-checking is sort of discouraged in Python
-        #       it makes the most sense to just treat evaluator as (always)
-        #       a function operating on detectors.
-        self.evaluator = evaluator
+        # XXX - This type of type-checking is discouraged - AS
+        if isinstance(evaluator, str):
+            self.evaluator = EVALUATORS[evaluator]
+        else:
+            self.evaluator = evaluator
 
     def update(self, X, y_true=None, y_pred=None):
         """

tests/menelaus/test_ensemble.py

@@ -14,7 +14,7 @@ def test_stream_ensemble_1():
     step3 = STEPD(window_size=2)
     se = StreamingEnsemble(
         detectors={"s1": step1, "s2": step2, "s3": step3},
-        evaluator=EVALUATORS["simple-majority"]
+        evaluator="simple-majority"
     )
     df = pd.DataFrame({"a": [0,0], "b": [0,0], "c": [0,0]})
     se.update(X=df.iloc[[0]], y_true=0, y_pred=0)