BUG: Update Styler.clear method to clear all (pandas-dev#40664)

Author: bsun94

doc/source/whatsnew/v1.3.0.rst

@@ -161,6 +161,7 @@ Other enhancements
 - :meth:`.Styler.apply` now more consistently accepts ndarray function returns, i.e. in all cases for ``axis`` is ``0, 1 or None`` (:issue:`39359`)
 - :meth:`.Styler.apply` and :meth:`.Styler.applymap` now raise errors if wrong format CSS is passed on render (:issue:`39660`)
 - :meth:`.Styler.format` adds keyword argument ``escape`` for optional HTML escaping (:issue:`40437`)
+- :meth:`.Styler.clear` now clears :attr:`Styler.hidden_index` and :attr:`Styler.hidden_columns` as well (:issue:`40484`)
 - Builtin highlighting methods in :class:`Styler` have a more consistent signature and css customisability (:issue:`40242`)
 - :meth:`Series.loc.__getitem__` and :meth:`Series.loc.__setitem__` with :class:`MultiIndex` now raising helpful error message when indexer has too many dimensions (:issue:`35349`)
 - :meth:`pandas.read_stata` and :class:`StataReader` support reading data from compressed files.

pandas/io/formats/style.py

@@ -881,7 +881,12 @@ def clear(self) -> None:
         self.ctx.clear()
         self.tooltips = None
         self.cell_context.clear()
-        self._todo = []
+        self._todo.clear()
+
+        self.hidden_index = False
+        self.hidden_columns = []
+        # self.format and self.table_styles may be dependent on user
+        # input in self.__init__()
 
     def _compute(self):
         """

pandas/tests/io/formats/style/test_style.py

@@ -174,10 +174,13 @@ def test_clear(self):
         tt = DataFrame({"A": [None, "tt"]})
         css = DataFrame({"A": [None, "cls-a"]})
         s = self.df.style.highlight_max().set_tooltips(tt).set_td_classes(css)
+        s = s.hide_index().hide_columns("A")
         # _todo, tooltips and cell_context items added to..
         assert len(s._todo) > 0
         assert s.tooltips
         assert len(s.cell_context) > 0
+        assert s.hidden_index is True
+        assert len(s.hidden_columns) > 0
 
         s = s._compute()
         # ctx item affected when a render takes place. _todo is maintained
@@ -190,6 +193,8 @@ def test_clear(self):
         assert len(s._todo) == 0
         assert not s.tooltips
         assert len(s.cell_context) == 0
+        assert s.hidden_index is False
+        assert len(s.hidden_columns) == 0
 
     def test_render(self):
         df = DataFrame({"A": [0, 1]})