pandas-dev · jreback · Jan 5, 2022 · Dec 30, 2021 · Dec 30, 2021 · Dec 30, 2021
diff --git a/doc/source/whatsnew/v1.4.0.rst b/doc/source/whatsnew/v1.4.0.rst
@@ -105,6 +105,7 @@ There are also some LaTeX specific enhancements:
 
  - :meth:`.Styler.to_latex` introduces keyword argument ``environment``, which also allows a specific "longtable" entry through a separate jinja2 template (:issue:`41866`).
  - Naive sparsification is now possible for LaTeX without the necessity of including the multirow package (:issue:`43369`)
+ - *cline* support has been added for MultiIndex row sparsification through a keyword argument (:issue:`45138`)
 
 .. _whatsnew_140.enhancements.pyarrow_csv_engine:
 

diff --git a/pandas/io/formats/style.py b/pandas/io/formats/style.py
@@ -494,6 +494,7 @@ def to_latex(
  position: str | None = None,
  position_float: str | None = None,
  hrules: bool | None = None,
+ clines: str | None = None,
  label: str | None = None,
  caption: str | tuple | None = None,
  sparse_index: bool | None = None,
@@ -542,6 +543,22 @@ def to_latex(
  Defaults to ``pandas.options.styler.latex.hrules``, which is `False`.
 
  .. versionchanged:: 1.4.0
+ clines : str, optional
+ Use to control adding \\cline commands for the index labels separation.
+ 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;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
+ table.
+ - `"skip-last;index"`: as above with lines extending only the width of the
+ index entries.
+
+ .. versionadded:: 1.4.0
  label : str, optional
  The LaTeX label included as: \\label{<label>}.
  This is used with \\ref{<label>} in the main .tex file.
@@ -911,6 +928,7 @@ def to_latex(
  environment=environment,
  convert_css=convert_css,
  siunitx=siunitx,
+ clines=clines,
  )
 
  encoding = encoding or get_option("styler.render.encoding")

diff --git a/pandas/io/formats/style_render.py b/pandas/io/formats/style_render.py
@@ -164,14 +164,16 @@ def _render_html(
  html_style_tpl=self.template_html_style,
  )
 
- def _render_latex(self, sparse_index: bool, sparse_columns: bool, **kwargs) -> str:
+ def _render_latex(
+ self, sparse_index: bool, sparse_columns: bool, clines: str | None, **kwargs
+ ) -> str:
  """
  Render a Styler in latex format
  """
  self._compute()
 
  d = self._translate(sparse_index, sparse_columns, blank="")
- self._translate_latex(d)
+ self._translate_latex(d, clines=clines)
 
  self.template_latex.globals["parse_wrap"] = _parse_latex_table_wrapping
  self.template_latex.globals["parse_table"] = _parse_latex_table_styles
@@ -257,13 +259,19 @@ def _translate(
  head = self._translate_header(sparse_cols, max_cols)
  d.update({"head": head})
 
+ # for sparsifying a MultiIndex and for use with latex clines
+ idx_lengths = _get_level_lengths(
+ self.index, sparse_index, max_rows, self.hidden_rows
+ )
+ d.update({"index_lengths": idx_lengths})
+
  self.cellstyle_map: DefaultDict[tuple[CSSPair, ...], list[str]] = defaultdict(
  list
  )
  self.cellstyle_map_index: DefaultDict[
  tuple[CSSPair, ...], list[str]
  ] = defaultdict(list)
- body = self._translate_body(sparse_index, max_rows, max_cols)
+ body = self._translate_body(idx_lengths, max_rows, max_cols)
  d.update({"body": body})
 
  ctx_maps = {
@@ -515,7 +523,7 @@ def _generate_index_names_row(self, iter: tuple, max_cols: int, col_lengths: dic
 
  return index_names + column_blanks
 
- def _translate_body(self, sparsify_index: bool, max_rows: int, max_cols: int):
+ def _translate_body(self, idx_lengths: dict, max_rows: int, max_cols: int):
  """
  Build each <tr> within table <body> as a list
 
@@ -537,11 +545,6 @@ def _translate_body(self, sparsify_index: bool, max_rows: int, max_cols: int):
  body : list
  The associated HTML elements needed for template rendering.
  """
- # for sparsifying a MultiIndex
- idx_lengths = _get_level_lengths(
- self.index, sparsify_index, max_rows, self.hidden_rows
- )
-
  rlabels = self.data.index.tolist()
  if not isinstance(self.data.index, MultiIndex):
  rlabels = [[x] for x in rlabels]
@@ -738,7 +741,7 @@ def _generate_body_row(
 
  return index_headers + data
 
- def _translate_latex(self, d: dict) -> None:
+ def _translate_latex(self, d: dict, clines: str | None) -> None:
  r"""
  Post-process the default render dict for the LaTeX template format.
 
@@ -749,10 +752,10 @@ def _translate_latex(self, d: dict) -> None:
  or multirow sparsification (so that \multirow and \multicol work correctly).
  """
  index_levels = self.index.nlevels
- visible_index_levels = index_levels - sum(self.hide_index_)
+ visible_index_level_n = index_levels - sum(self.hide_index_)
  d["head"] = [
  [
- {**col, "cellstyle": self.ctx_columns[r, c - visible_index_levels]}
+ {**col, "cellstyle": self.ctx_columns[r, c - visible_index_level_n]}
  for c, col in enumerate(row)
  if col["is_visible"]
  ]
@@ -790,6 +793,39 @@ def _translate_latex(self, d: dict) -> None:
  body.append(row_body_headers + row_body_cells)
  d["body"] = body
 
+ # clines are determined from info on index_lengths and hidden_rows and input
+ # to a dict defining which row clines should be added in the template.
+ if clines not in [
+ None,
+ "all;data",
+ "all;index",
+ "skip-last;data",
+ "skip-last;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'."
+ )
+ elif clines is not None:
+ data_len = len(row_body_cells) if "data" in clines else 0
+
+ d["clines"] = defaultdict(list)
+ visible_row_indexes: list[int] = [
+ r for r in range(len(self.data.index)) if r not in self.hidden_rows
+ ]
+ visible_index_levels: list[int] = [
+ i for i in range(index_levels) if not self.hide_index_[i]
+ ]
+ for rn, r in enumerate(visible_row_indexes):
+ for lvln, lvl in enumerate(visible_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}}}"
+ )
+
  def format(
  self,
  formatter: ExtFormatter | None = None,

diff --git a/pandas/io/formats/templates/latex_longtable.tpl b/pandas/io/formats/templates/latex_longtable.tpl
@@ -73,6 +73,10 @@
 {% for c in row %}{% if not loop.first %} & {% endif %}
  {%- if c.type == 'th' %}{{parse_header(c, multirow_align, multicol_align)}}{% else %}{{parse_cell(c.cellstyle, c.display_value, convert_css)}}{% endif %}
 {%- endfor %} \\
+{% if clines and clines[loop.index] | length > 0 %}
+ {%- for cline in clines[loop.index] %}{% if not loop.first %} {% endif %}{{ cline }}{% endfor %}
+
+{% endif %}
 {% endfor %}
 \end{longtable}
 {% raw %}{% endraw %}
diff --git a/pandas/io/formats/templates/latex_table.tpl b/pandas/io/formats/templates/latex_table.tpl
@@ -41,6 +41,10 @@
 {% for c in row %}{% if not loop.first %} & {% endif %}
  {%- if c.type == 'th' %}{{parse_header(c, multirow_align, multicol_align, False, convert_css)}}{% else %}{{parse_cell(c.cellstyle, c.display_value, convert_css)}}{% endif %}
 {%- endfor %} \\
+{% if clines and clines[loop.index] | length > 0 %}
+ {%- for cline in clines[loop.index] %}{% if not loop.first %} {% endif %}{{ cline }}{% endfor %}
+
+{% endif %}
 {% endfor %}
 {% set bottomrule = parse_table(table_styles, 'bottomrule') %}
 {% if bottomrule is not none %}

diff --git a/pandas/tests/io/formats/style/test_to_latex.py b/pandas/tests/io/formats/style/test_to_latex.py
@@ -876,3 +876,117 @@ def test_apply_index_hidden_levels():
  """
  )
  assert result == expected
+
+
+@pytest.mark.parametrize("clines", ["bad", "index", "skip-last", "all", "data"])
+def test_clines_validation(clines, styler):
+ msg = f"`clines` value of {clines} is invalid."
+ with pytest.raises(ValueError, match=msg):
+ styler.to_latex(clines=clines)
+
+
+@pytest.mark.parametrize(
+ "clines, exp",
+ [
+ ("all;index", "\n\\cline{1-1}"),
+ ("all;data", "\n\\cline{1-2}"),
+ ("skip-last;index", ""),
+ ("skip-last;data", ""),
+ (None, ""),
+ ],
+)
+@pytest.mark.parametrize("env", ["table", "longtable"])
+def test_clines_index(clines, exp, env):
+ df = DataFrame([[1], [2], [3], [4]])
+ result = df.style.to_latex(clines=clines, environment=env)
+ expected = f"""\
+0 & 1 \\\\{exp}
+1 & 2 \\\\{exp}
+2 & 3 \\\\{exp}
+3 & 4 \\\\{exp}
+"""
+ assert expected in result
+
+
+@pytest.mark.parametrize(
+ "clines, expected",
+ [
+ (
+ None,
+ dedent(
+ """\
+ \\multirow[c]{2}{*}{A} & X & 1 \\\\
+ & Y & 2 \\\\
+ \\multirow[c]{2}{*}{B} & X & 3 \\\\
+ & Y & 4 \\\\
+ """
+ ),
+ ),
+ (
+ "skip-last;index",
+ dedent(
+ """\
+ \\multirow[c]{2}{*}{A} & X & 1 \\\\
+ & Y & 2 \\\\
+ \\cline{1-2}
+ \\multirow[c]{2}{*}{B} & X & 3 \\\\
+ & Y & 4 \\\\
+ \\cline{1-2}
+ """
+ ),
+ ),
+ (
+ "skip-last;data",
+ dedent(
+ """\
+ \\multirow[c]{2}{*}{A} & X & 1 \\\\
+ & Y & 2 \\\\
+ \\cline{1-3}
+ \\multirow[c]{2}{*}{B} & X & 3 \\\\
+ & Y & 4 \\\\
+ \\cline{1-3}
+ """
+ ),
+ ),
+ (
+ "all;index",
+ dedent(
+ """\
+ \\multirow[c]{2}{*}{A} & X & 1 \\\\
+ \\cline{2-2}
+ & Y & 2 \\\\
+ \\cline{1-2} \\cline{2-2}
+ \\multirow[c]{2}{*}{B} & X & 3 \\\\
+ \\cline{2-2}
+ & Y & 4 \\\\
+ \\cline{1-2} \\cline{2-2}
+ """
+ ),
+ ),
+ (
+ "all;data",
+ dedent(
+ """\
+ \\multirow[c]{2}{*}{A} & X & 1 \\\\
+ \\cline{2-3}
+ & Y & 2 \\\\
+ \\cline{1-3} \\cline{2-3}
+ \\multirow[c]{2}{*}{B} & X & 3 \\\\
+ \\cline{2-3}
+ & Y & 4 \\\\
+ \\cline{1-3} \\cline{2-3}
+ """
+ ),
+ ),
+ ],
+)
+@pytest.mark.parametrize("env", ["table"])
+def test_clines_multiindex(clines, expected, env):
+ # also tests simultaneously with hidden rows and a hidden multiindex level
+ midx = MultiIndex.from_product([["A", "-", "B"], [0], ["X", "Y"]])
+ df = DataFrame([[1], [2], [99], [99], [3], [4]], index=midx)
+ styler = df.style
+ styler.hide([("-", 0, "X"), ("-", 0, "Y")])
+ styler.hide(level=1)
+ result = styler.to_latex(clines=clines, environment=env)
+ assert expected in result