Deepcopy of posterior to allow second fit call (#790)

pymc_marketing/mmm/delayed_saturated_mmm.py

@@ -1819,6 +1819,7 @@ def add_lift_test_measurements(
             time_varying_var_name=time_varying_var_name,
             model=self.model,
             dist=dist,
+            name=name,
         )
 
     def _create_synth_dataset(

pymc_marketing/model_builder.py

@@ -471,6 +471,7 @@ def fit(
             idata = pm.sample(**sampler_args)
 
         if self.idata:
+            self.idata = self.idata.copy()
             self.idata.extend(idata, join="right")
         else:
             self.idata = idata
@@ -479,6 +480,10 @@ def fit(
         combined_data = pd.concat([X_df, y_df], axis=1)
         if not all(combined_data.columns):
             raise ValueError("All columns must have non-empty names")
+
+        if "fit_data" in self.idata:
+            del self.idata.fit_data
+
         with warnings.catch_warnings():
             warnings.filterwarnings(
                 "ignore",

tests/mmm/test_base.py

@@ -225,8 +225,6 @@ def transform(self, X):
 
 
 def test_validate_and_preprocess(toy_X, toy_y, test_mmm):
-    test_mmm
-
     test_mmm.validate("X", toy_X)
     test_mmm.mock_method1.assert_called_once_with(test_mmm, toy_X)
 

tests/test_model_builder.py

@@ -352,3 +352,17 @@ def test_fit_after_prior_keeps_prior(toy_X, toy_y):
     model.fit(X=toy_X, y=toy_y, chains=1, draws=100, tune=100)
     assert "prior" in model.idata
     assert "prior_predictive" in model.idata
+
+
+def test_second_fit(toy_X, toy_y):
+    model = ModelBuilderTest()
+
+    model.fit(X=toy_X, y=toy_y, chains=1, draws=100, tune=100)
+    assert "posterior" in model.idata
+    id_before = id(model.idata)
+    assert "fit_data" in model.idata
+
+    model.fit(X=toy_X, y=toy_y, chains=1, draws=100, tune=100)
+    id_after = id(model.idata)
+
+    assert id_before != id_after