minor requests

Author: attack68

doc/source/whatsnew/v1.3.0.rst

@@ -54,6 +54,7 @@ Other enhancements
 - Add support for dict-like names in :class:`MultiIndex.set_names` and :class:`MultiIndex.rename` (:issue:`20421`)
 - :func:`pandas.read_excel` can now auto detect .xlsb files (:issue:`35416`)
 - :meth:`.Rolling.sum`, :meth:`.Expanding.sum`, :meth:`.Rolling.mean`, :meth:`.Expanding.mean`, :meth:`.Rolling.median`, :meth:`.Expanding.median`, :meth:`.Rolling.max`, :meth:`.Expanding.max`, :meth:`.Rolling.min`, and :meth:`.Expanding.min` now support ``Numba`` execution with the ``engine`` keyword (:issue:`38895`)
+- :meth:`.Styler.set_tooltips` allows on hover tooltips to be added to styled HTML dataframes.
 
 .. ---------------------------------------------------------------------------
 

pandas/io/formats/style.py

@@ -805,7 +805,7 @@ def clear(self) -> None:
         Returns None.
         """
         self.ctx.clear()
-        self.tooltips = None
+        self.tooltips: Optional[_Tooltips] = None
         self.cell_context = {}
         self._todo = []
 
@@ -1934,6 +1934,7 @@ def _translate(self, styler_data: FrameOrSeriesUnion, uuid: str, d: Dict):
         ]
 
         if self.table_styles:
+            # add span class to every cell only if at least 1 non-empty tooltip
             for row in d["body"]:
                 for item in row:
                     if item["type"] == "td":