Allow Negative Values in Media Channels

pymc_marketing/mmm/validating.py

@@ -14,6 +14,7 @@
 """Validating methods for MMM classes."""
 
 from collections.abc import Callable
+from warnings import warn
 
 import pandas as pd
 
@@ -116,8 +117,10 @@ def validate_channel_columns(self, data: pd.DataFrame) -> None:
                 f"channel_columns {self.channel_columns} contains duplicates"
             )
         if (data.filter(list(self.channel_columns)) < 0).any().any():
-            raise ValueError(
-                f"channel_columns {self.channel_columns} contains negative values"
+            warn(
+                f"channel_columns {self.channel_columns} contains negative values",
+                UserWarning,
+                stacklevel=2,
             )
 
 

tests/mmm/test_validating.py

@@ -114,8 +114,8 @@ def test_channel_columns():
     ):
         obj.channel_columns = ["channel_1", "channel_1"]
         obj.validate_channel_columns(toy_X)
-    with pytest.raises(
-        ValueError,
+    with pytest.warns(
+        UserWarning,
         match=r"channel_columns \['channel_1'\] contains negative values",
     ):
         new_toy_X = toy_X.copy()