ENH: Be able to add lines for all index levels, not just visible ones [fix #59877]

doc/source/whatsnew/v3.0.0.rst

@@ -64,6 +64,7 @@ Other enhancements
 - Support passing a :class:`Iterable[Hashable]` input to :meth:`DataFrame.drop_duplicates` (:issue:`59237`)
 - Support reading Stata 102-format (Stata 1) dta files (:issue:`58978`)
 - Support reading Stata 110-format (Stata 7) dta files (:issue:`47176`)
+- :meth:`Styler.to_latex` accepts additional options to the ``clines`` parameter, allowing lines to be drawn between hidden index levels.
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_300.notable_bug_fixes:

pandas/io/formats/style.py

@@ -717,17 +717,27 @@ def to_latex(
             Possible values are:
 
               - `None`: no cline commands are added (default).
-              - `"all;data"`: a cline is added for every index value extending the
-                width of the table, including data entries.
+              - `"all;data"`: a cline is added for every visible index value extending
+                the width of the table, including data entries.
               - `"all;index"`: as above with lines extending only the width of the
                 index entries.
-              - `"skip-last;data"`: a cline is added for each index value except the
-                last level (which is never sparsified), extending the widtn of the
+              - `"all-invisible;data"`: a cline is added for every index value,
+                including hidden indexes, extending the full width of the table,
+                including data entries.
+              - `"all-invisible;index"`: as above with lines extending only the width
+                of the index entries.
+              - `"skip-last;data"`: a cline is added for each visible index value except
+                the last level (which is never sparsified), extending the widtn of the
                 table.
               - `"skip-last;index"`: as above with lines extending only the width of the
                 index entries.
+              - `"skip-last-invisible;data"`: a cline is added for each index value,
+                including hidden index levels, but excluding the last (which is never
+                sparsified), extending the width of the table.
+              - `"skip-last-invisible;index"`: as above with lines extending only the
+                width of the index entries.
 
-            .. versionadded:: 1.4.0
+            .. versionchanged:: 3.0.0
         label : str, optional
             The LaTeX label included as: \\label{<label>}.
             This is used with \\ref{<label>} in the main .tex file.

pandas/io/formats/style_render.py

@@ -933,12 +933,18 @@ def concatenated_visible_rows(obj):
             None,
             "all;data",
             "all;index",
+            "all-invisible;data",
+            "all-invisible;index",
             "skip-last;data",
             "skip-last;index",
+            "skip-last-invisible;data",
+            "skip-last-invisible;index",
         ]:
             raise ValueError(
                 f"`clines` value of {clines} is invalid. Should either be None or one "
-                f"of 'all;data', 'all;index', 'skip-last;data', 'skip-last;index'."
+                f"of 'all;data', 'all;index', 'all-invisible;data', "
+                f"'all-invisible;index', 'skip-last;data', 'skip-last;index', "
+                f"'skip-last-invisible;data', 'skip-last-invisible;index'."
             )
         if clines is not None:
             data_len = len(row_body_cells) if "data" in clines and d["body"] else 0
@@ -950,15 +956,26 @@ def concatenated_visible_rows(obj):
             visible_index_levels: list[int] = [
                 i for i in range(index_levels) if not self.hide_index_[i]
             ]
+            target_index_levels: list[int] = [
+                i
+                for i in range(index_levels)
+                if "invisible" in clines or not self.hide_index_[i]
+            ]
             for rn, r in enumerate(visible_row_indexes):
-                for lvln, lvl in enumerate(visible_index_levels):
+                lvln = 0
+                for lvl in target_index_levels:
                     if lvl == index_levels - 1 and "skip-last" in clines:
                         continue
                     idx_len = d["index_lengths"].get((lvl, r), None)
                     if idx_len is not None:  # i.e. not a sparsified entry
-                        d["clines"][rn + idx_len].append(
-                            f"\\cline{{{lvln+1}-{len(visible_index_levels)+data_len}}}"
-                        )
+                        cline_start_col = lvln + 1
+                        cline_end_col = len(visible_index_levels) + data_len
+                        if cline_end_col >= cline_start_col:
+                            d["clines"][rn + idx_len].append(
+                                f"\\cline{{{cline_start_col}-{cline_end_col}}}"
+                            )
+                    if lvl in visible_index_levels:
+                        lvln += 1
 
     def format(
         self,

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

@@ -896,8 +896,12 @@ def test_clines_validation(clines, styler):
     [
         ("all;index", "\n\\cline{1-1}"),
         ("all;data", "\n\\cline{1-2}"),
+        ("all-invisible;index", "\n\\cline{1-1}"),
+        ("all-invisible;data", "\n\\cline{1-2}"),
         ("skip-last;index", ""),
         ("skip-last;data", ""),
+        ("skip-last-invisible;index", ""),
+        ("skip-last-invisible;data", ""),
         (None, ""),
     ],
 )
@@ -984,6 +988,62 @@ def test_clines_index(clines, exp, env):
             """
             ),
         ),
+        (
+            "skip-last-invisible;index",
+            dedent(
+                """\
+            \\multirow[c]{2}{*}{A} & X & 1 \\\\
+             & Y & 2 \\\\
+            \\cline{1-2} \\cline{2-2}
+            \\multirow[c]{2}{*}{B} & X & 3 \\\\
+             & Y & 4 \\\\
+            \\cline{1-2} \\cline{2-2}
+            """
+            ),
+        ),
+        (
+            "skip-last-invisible;data",
+            dedent(
+                """\
+            \\multirow[c]{2}{*}{A} & X & 1 \\\\
+             & Y & 2 \\\\
+            \\cline{1-3} \\cline{2-3}
+            \\multirow[c]{2}{*}{B} & X & 3 \\\\
+             & Y & 4 \\\\
+            \\cline{1-3} \\cline{2-3}
+            """
+            ),
+        ),
+        (
+            "all-invisible;index",
+            dedent(
+                """\
+            \\multirow[c]{2}{*}{A} & X & 1 \\\\
+            \\cline{2-2}
+             & Y & 2 \\\\
+            \\cline{1-2} \\cline{2-2} \\cline{2-2}
+            \\multirow[c]{2}{*}{B} & X & 3 \\\\
+            \\cline{2-2}
+             & Y & 4 \\\\
+            \\cline{1-2} \\cline{2-2} \\cline{2-2}
+            """
+            ),
+        ),
+        (
+            "all-invisible;data",
+            dedent(
+                """\
+            \\multirow[c]{2}{*}{A} & X & 1 \\\\
+            \\cline{2-3}
+             & Y & 2 \\\\
+            \\cline{1-3} \\cline{2-3} \\cline{2-3}
+            \\multirow[c]{2}{*}{B} & X & 3 \\\\
+            \\cline{2-3}
+             & Y & 4 \\\\
+            \\cline{1-3} \\cline{2-3} \\cline{2-3}
+            """
+            ),
+        ),
     ],
 )
 @pytest.mark.parametrize("env", ["table"])
@@ -998,6 +1058,58 @@ def test_clines_multiindex(clines, expected, env):
     assert expected in result
 
 
+@pytest.mark.parametrize(
+    "clines, expected",
+    [
+        (None, "1 \\\\\n2 \\\\\n3 \\\\\n4 \\\\\n"),
+        ("all;data", "1 \\\\\n2 \\\\\n3 \\\\\n4 \\\\\n"),
+        ("all;index", "1 \\\\\n2 \\\\\n3 \\\\\n4 \\\\\n"),
+        ("skip-last;data", "1 \\\\\n2 \\\\\n3 \\\\\n4 \\\\\n"),
+        ("skip-last;index", "1 \\\\\n2 \\\\\n3 \\\\\n4 \\\\\n"),
+        ("all-invisible;index", "1 \\\\\n2 \\\\\n3 \\\\\n4 \\\\\n"),
+        ("skip-last-invisible;index", "1 \\\\\n2 \\\\\n3 \\\\\n4 \\\\\n"),
+        (
+            "all-invisible;data",
+            dedent(
+                """\
+            1 \\\\
+            \\cline{1-1}
+            2 \\\\
+            \\cline{1-1} \\cline{1-1}
+            3 \\\\
+            \\cline{1-1}
+            4 \\\\
+            \\cline{1-1} \\cline{1-1}
+            """
+            ),
+        ),
+        (
+            "skip-last-invisible;data",
+            dedent(
+                """\
+            1 \\\\
+            2 \\\\
+            \\cline{1-1}
+            3 \\\\
+            4 \\\\
+            \\cline{1-1}
+            """
+            ),
+        ),
+    ],
+)
+@pytest.mark.parametrize("env", ["table"])
+def test_clines_hiddenindex(clines, expected, env):
+    # Make sure that \clines are correctly hidden or shown with all indixes hidden
+    midx = MultiIndex.from_product([["A", "-", "B"], ["X", "Y"]])
+    df = DataFrame([[1], [2], [99], [99], [3], [4]], index=midx)
+    styler = df.style
+    styler.hide([("-", "X"), ("-", "Y")])
+    styler.hide(axis=0)
+    result = styler.to_latex(clines=clines, environment=env)
+    assert expected in result
+
+
 def test_col_format_len(styler):
     # gh 46037
     result = styler.to_latex(environment="longtable", column_format="lrr{10cm}")