Do not rescale seasonality. (#130)

src/sid/seasonality.py

@@ -51,13 +51,12 @@ def prepare_seasonality_factor(
                 "with 'dates' as index and seasonality factors as data."
             )
 
-        # Make sure the highest multiplier is set to one so that random contacts only
-        # need to be reduced by the infection probability of the contact model.
-        for col in factor:
-            factor[col] = factor[col] / factor[col].max()
-            if not factor[col].between(0, 1).all():
-                raise ValueError(
-                    "The seasonality factors need to lie in the interval [0, 1]."
-                )
+    factor = factor.astype(float)
+
+    for col in factor:
+        if not factor[col].between(0, 1).all():
+            raise ValueError(
+                "The seasonality factors need to lie in the interval [0, 1]."
+            )
 
     return factor

tests/test_seasonality.py

@@ -49,11 +49,11 @@ def test_simulate_a_simple_model(params, initial_states, tmp_path):
                 index=pd.date_range("2020-01-01", periods=2),
                 data=1,
                 columns=["meet_two_people"],
-            ),
+            ).astype(float),
             {"meet_two_people": {}},
         ),
         pytest.param(
-            lambda params, dates, seed: pd.Series(index=dates, data=[1, 2, 3]),
+            lambda params, dates, seed: pd.Series(index=dates, data=[1 / 3, 2 / 3, 1]),
             None,
             pd.date_range("2020-01-01", periods=3),
             does_not_raise(),