ENH: sparse_columns and sparse_index added to Styler.to_html (pandas-dev#41946)

Author: attack68

doc/source/whatsnew/v1.4.0.rst

@@ -35,6 +35,7 @@ Other enhancements
 -  Additional options added to :meth:`.Styler.bar` to control alignment and display, with keyword only arguments (:issue:`26070`, :issue:`36419`)
 - :meth:`Styler.bar` now validates the input argument ``width`` and ``height`` (:issue:`42511`)
 - :meth:`Series.ewm`, :meth:`DataFrame.ewm`, now support a ``method`` argument with a ``'table'`` option that performs the windowing operation over an entire :class:`DataFrame`. See :ref:`Window Overview <window.overview>` for performance and functional benefits (:issue:`42273`)
+- Added ``sparse_index`` and ``sparse_columns`` keyword arguments to :meth:`.Styler.to_html` (:issue:`41946`)
 - Added keyword argument ``environment`` to :meth:`.Styler.to_latex` also allowing a specific "longtable" entry with a separate jinja2 template (:issue:`41866`)
 -
 

pandas/io/formats/style.py

@@ -476,8 +476,8 @@ def to_latex(
             Defaults to ``pandas.options.styler.sparse.index`` value.
         sparse_columns : bool, optional
             Whether to sparsify the display of a hierarchical index. Setting to False
-            will display each explicit level element in a hierarchical key for each row.
-            Defaults to ``pandas.options.styler.sparse.columns`` value.
+            will display each explicit level element in a hierarchical key for each
+            column. Defaults to ``pandas.options.styler.sparse.columns`` value.
         multirow_align : {"c", "t", "b"}
             If sparsifying hierarchical MultiIndexes whether to align text centrally,
             at the top or bottom.
@@ -815,6 +815,8 @@ def to_html(
         *,
         table_uuid: str | None = None,
         table_attributes: str | None = None,
+        sparse_index: bool | None = None,
+        sparse_columns: bool | None = None,
         encoding: str | None = None,
         doctype_html: bool = False,
         exclude_styles: bool = False,
@@ -840,6 +842,18 @@ def to_html(
             ``<table .. <table_attributes> >``
 
             If not given defaults to Styler's preexisting value.
+        sparse_index : bool, optional
+            Whether to sparsify the display of a hierarchical index. Setting to False
+            will display each explicit level element in a hierarchical key for each row.
+            Defaults to ``pandas.options.styler.sparse.index`` value.
+
+            .. versionadded:: 1.4.0
+        sparse_columns : bool, optional
+            Whether to sparsify the display of a hierarchical index. Setting to False
+            will display each explicit level element in a hierarchical key for each
+            column. Defaults to ``pandas.options.styler.sparse.columns`` value.
+
+            .. versionadded:: 1.4.0
         encoding : str, optional
             Character encoding setting for file output, and HTML meta tags,
             defaults to "utf-8" if None.
@@ -866,8 +880,15 @@ def to_html(
         if table_attributes:
             self.set_table_attributes(table_attributes)
 
+        if sparse_index is None:
+            sparse_index = get_option("styler.sparse.index")
+        if sparse_columns is None:
+            sparse_columns = get_option("styler.sparse.columns")
+
         # Build HTML string..
-        html = self.render(
+        html = self._render_html(
+            sparse_index=sparse_index,
+            sparse_columns=sparse_columns,
             exclude_styles=exclude_styles,
             encoding=encoding if encoding else "utf-8",
             doctype_html=doctype_html,

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

@@ -6,6 +6,7 @@
 from pandas import (
     DataFrame,
     MultiIndex,
+    option_context,
 )
 
 jinja2 = pytest.importorskip("jinja2")
@@ -429,3 +430,24 @@ def test_sticky_levels(styler_mi, index, columns):
 def test_sticky_raises(styler):
     with pytest.raises(ValueError, match="`axis` must be"):
         styler.set_sticky(axis="bad")
+
+
+@pytest.mark.parametrize(
+    "sparse_index, sparse_columns",
+    [(True, True), (True, False), (False, True), (False, False)],
+)
+def test_sparse_options(sparse_index, sparse_columns):
+    cidx = MultiIndex.from_tuples([("Z", "a"), ("Z", "b"), ("Y", "c")])
+    ridx = MultiIndex.from_tuples([("A", "a"), ("A", "b"), ("B", "c")])
+    df = DataFrame([[1, 2, 3], [4, 5, 6], [7, 8, 9]], index=ridx, columns=cidx)
+    styler = df.style
+
+    default_html = styler.to_html()  # defaults under pd.options to (True , True)
+
+    with option_context(
+        "styler.sparse.index", sparse_index, "styler.sparse.columns", sparse_columns
+    ):
+        html1 = styler.to_html()
+        assert (html1 == default_html) is (sparse_index and sparse_columns)
+    html2 = styler.to_html(sparse_index=sparse_index, sparse_columns=sparse_columns)
+    assert html1 == html2