[BUG] Force softmax returning Series (pyjanitor-devs#1139)

Author: Zeroto521

CHANGELOG.md

@@ -14,6 +14,7 @@
 -   [ENH] Add `names_expand` and `index_expand` parameters to `pivot_wider` for exposing missing categoricals. Issue #1108 @samukweku
 -   [ENH] Add fix  for slicing error when selecting columns in `pivot_wider`. Issue #1134 @samukweku
 -   [ENH] `dropna` parameter added to `pivot_longer`. Issue #1132 @samukweku
+-   [BUG] Force `math.softmax` returning `Series`. PR #1139 @Zeroto521
 
 ## [v0.23.1] - 2022-05-03
 

janitor/math.py

@@ -124,7 +124,8 @@ def softmax(s: pd.Series) -> pd.Series:
     :param s: Input Series.
     :return: Transformed Series.
     """
-    return scipy_softmax(s)
+
+    return pd.Series(scipy_softmax(s), index=s.index, name=s.name)
 
 
 @pf.register_series_method