REF: styler.to_latex siunitx changes: render {} only when needed.

pandas/io/formats/style.py

@@ -861,6 +861,7 @@ def to_latex(
             multicol_align=multicol_align,
             environment=environment,
             convert_css=convert_css,
+            siunitx=siunitx,
         )
 
         encoding = encoding or get_option("styler.render.encoding")

pandas/io/formats/templates/latex_longtable.tpl

@@ -29,7 +29,7 @@
 \{{toprule}}
 {% endif %}
 {% for row in head %}
-{% for c in row %}{%- if not loop.first %} & {% endif %}{{parse_header(c, multirow_align, multicol_align, True)}}{% endfor %} \\
+{% for c in row %}{%- if not loop.first %} & {% endif %}{{parse_header(c, multirow_align, multicol_align, siunitx)}}{% endfor %} \\
 {% endfor %}
 {% set midrule = parse_table(table_styles, 'midrule') %}
 {% if midrule is not none %}
@@ -45,7 +45,7 @@
 \{{toprule}}
 {% endif %}
 {% for row in head %}
-{% for c in row %}{%- if not loop.first %} & {% endif %}{{parse_header(c, multirow_align, multicol_align, True)}}{% endfor %} \\
+{% for c in row %}{%- if not loop.first %} & {% endif %}{{parse_header(c, multirow_align, multicol_align, siunitx)}}{% endfor %} \\
 {% endfor %}
 {% if midrule is not none %}
 \{{midrule}}

pandas/io/formats/templates/latex_table.tpl

@@ -31,7 +31,7 @@
 \{{toprule}}
 {% endif %}
 {% for row in head %}
-{% for c in row %}{%- if not loop.first %} & {% endif %}{{parse_header(c, multirow_align, multicol_align, True)}}{% endfor %} \\
+{% for c in row %}{%- if not loop.first %} & {% endif %}{{parse_header(c, multirow_align, multicol_align, siunitx)}}{% endfor %} \\
 {% endfor %}
 {% set midrule = parse_table(table_styles, 'midrule') %}
 {% if midrule is not none %}

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

@@ -131,7 +131,7 @@ def test_latex_non_unique(styler):
     assert result == dedent(
         """\
         \\begin{tabular}{lrrr}
-        {} & {c} & {d} & {d} \\\\
+         & c & d & d \\\\
         i & 1.000000 & 2.000000 & 3.000000 \\\\
         j & 4.000000 & 5.000000 & 6.000000 \\\\
         j & 7.000000 & 8.000000 & 9.000000 \\\\

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

@@ -33,7 +33,7 @@ def test_minimal_latex_tabular(styler):
     expected = dedent(
         """\
         \\begin{tabular}{lrrl}
-        {} & {A} & {B} & {C} \\\\
+         & A & B & C \\\\
         0 & 0 & -0.61 & ab \\\\
         1 & 1 & -1.22 & cd \\\\
         \\end{tabular}
@@ -47,7 +47,7 @@ def test_tabular_hrules(styler):
         """\
         \\begin{tabular}{lrrl}
         \\toprule
-        {} & {A} & {B} & {C} \\\\
+         & A & B & C \\\\
         \\midrule
         0 & 0 & -0.61 & ab \\\\
         1 & 1 & -1.22 & cd \\\\
@@ -69,7 +69,7 @@ def test_tabular_custom_hrules(styler):
         """\
         \\begin{tabular}{lrrl}
         \\hline
-        {} & {A} & {B} & {C} \\\\
+         & A & B & C \\\\
         0 & 0 & -0.61 & ab \\\\
         1 & 1 & -1.22 & cd \\\\
         \\otherline
@@ -169,7 +169,7 @@ def test_cell_styling(styler):
     expected = dedent(
         """\
         \\begin{tabular}{lrrl}
-        {} & {A} & {B} & {C} \\\\
+         & A & B & C \\\\
         0 & 0 & \\itshape {\\Huge -0.61} & ab \\\\
         1 & \\itshape {\\Huge 1} & -1.22 & \\itshape {\\Huge cd} \\\\
         \\end{tabular}
@@ -184,8 +184,8 @@ def test_multiindex_columns(df):
     expected = dedent(
         """\
         \\begin{tabular}{lrrl}
-        {} & \\multicolumn{2}{r}{A} & {B} \\\\
-        {} & {a} & {b} & {c} \\\\
+         & \\multicolumn{2}{r}{A} & B \\\\
+         & a & b & c \\\\
         0 & 0 & -0.61 & ab \\\\
         1 & 1 & -1.22 & cd \\\\
         \\end{tabular}
@@ -198,8 +198,8 @@ def test_multiindex_columns(df):
     expected = dedent(
         """\
         \\begin{tabular}{lrrl}
-        {} & {A} & {A} & {B} \\\\
-        {} & {a} & {b} & {c} \\\\
+         & A & A & B \\\\
+         & a & b & c \\\\
         0 & 0 & -0.61 & ab \\\\
         1 & 1 & -1.22 & cd \\\\
         \\end{tabular}
@@ -217,7 +217,7 @@ def test_multiindex_row(df):
     expected = dedent(
         """\
         \\begin{tabular}{llrrl}
-        {} & {} & {A} & {B} & {C} \\\\
+         &  & A & B & C \\\\
         \\multirow[c]{2}{*}{A} & a & 0 & -0.61 & ab \\\\
          & b & 1 & -1.22 & cd \\\\
         B & c & 2 & -2.22 & de \\\\
@@ -231,7 +231,7 @@ def test_multiindex_row(df):
     expected = dedent(
         """\
         \\begin{tabular}{llrrl}
-        {} & {} & {A} & {B} & {C} \\\\
+         &  & A & B & C \\\\
         A & a & 0 & -0.61 & ab \\\\
         A & b & 1 & -1.22 & cd \\\\
         B & c & 2 & -2.22 & de \\\\
@@ -250,8 +250,8 @@ def test_multiindex_row_and_col(df):
     expected = dedent(
         """\
         \\begin{tabular}{llrrl}
-        {} & {} & \\multicolumn{2}{l}{Z} & {Y} \\\\
-        {} & {} & {a} & {b} & {c} \\\\
+         &  & \\multicolumn{2}{l}{Z} & Y \\\\
+         &  & a & b & c \\\\
         \\multirow[b]{2}{*}{A} & a & 0 & -0.61 & ab \\\\
          & b & 1 & -1.22 & cd \\\\
         B & c & 2 & -2.22 & de \\\\
@@ -265,8 +265,8 @@ def test_multiindex_row_and_col(df):
     expected = dedent(
         """\
         \\begin{tabular}{llrrl}
-        {} & {} & {Z} & {Z} & {Y} \\\\
-        {} & {} & {a} & {b} & {c} \\\\
+         &  & Z & Z & Y \\\\
+         &  & a & b & c \\\\
         A & a & 0 & -0.61 & ab \\\\
         A & b & 1 & -1.22 & cd \\\\
         B & c & 2 & -2.22 & de \\\\
@@ -286,15 +286,15 @@ def test_multi_options(df):
 
     expected = dedent(
         """\
-    {} & {} & \\multicolumn{2}{r}{Z} & {Y} \\\\
-    {} & {} & {a} & {b} & {c} \\\\
+     &  & \\multicolumn{2}{r}{Z} & Y \\\\
+     &  & a & b & c \\\\
     \\multirow[c]{2}{*}{A} & a & 0 & -0.61 & ab \\\\
     """
     )
     assert expected in styler.to_latex()
 
     with option_context("styler.latex.multicol_align", "l"):
-        assert "{} & {} & \\multicolumn{2}{l}{Z} & {Y} \\\\" in styler.to_latex()
+        assert " &  & \\multicolumn{2}{l}{Z} & Y \\\\" in styler.to_latex()
 
     with option_context("styler.latex.multirow_align", "b"):
         assert "\\multirow[b]{2}{*}{A} & a & 0 & -0.61 & ab \\\\" in styler.to_latex()
@@ -341,7 +341,7 @@ def test_hidden_index(styler):
     expected = dedent(
         """\
         \\begin{tabular}{rrl}
-        {A} & {B} & {C} \\\\
+        A & B & C \\\\
         0 & -0.61 & ab \\\\
         1 & -1.22 & cd \\\\
         \\end{tabular}
@@ -384,8 +384,8 @@ def test_comprehensive(df, environment):
 \\rowcolors{3}{pink}{}
 \\begin{tabular}{rlrlr}
 \\toprule
-{} & {} & \\multicolumn{2}{r}{Z} & {Y} \\\\
-{} & {} & {a} & {b} & {c} \\\\
+ &  & \\multicolumn{2}{r}{Z} & Y \\\\
+ &  & a & b & c \\\\
 \\midrule
 \\multirow[c]{2}{*}{A} & a & 0 & \\textbf{\\cellcolor[rgb]{1,1,0.6}{-0.61}} & ab \\\\
  & b & 1 & -1.22 & cd \\\\
@@ -579,12 +579,12 @@ def test_longtable_comprehensive(styler):
         \\begin{longtable}{lrrl}
         \\caption[short]{full} \\label{fig:A} \\\\
         \\toprule
-        {} & {A} & {B} & {C} \\\\
+         & A & B & C \\\\
         \\midrule
         \\endfirsthead
         \\caption[]{full} \\\\
         \\toprule
-        {} & {A} & {B} & {C} \\\\
+         & A & B & C \\\\
         \\midrule
         \\endhead
         \\midrule
@@ -606,9 +606,9 @@ def test_longtable_minimal(styler):
     expected = dedent(
         """\
         \\begin{longtable}{lrrl}
-        {} & {A} & {B} & {C} \\\\
+         & A & B & C \\\\
         \\endfirsthead
-        {} & {A} & {B} & {C} \\\\
+         & A & B & C \\\\
         \\endhead
         \\multicolumn{4}{r}{Continued on next page} \\\\
         \\endfoot
@@ -622,27 +622,34 @@ def test_longtable_minimal(styler):
 
 
 @pytest.mark.parametrize(
-    "sparse, exp",
+    "sparse, exp, siunitx",
     [
-        (True, "{} & \\multicolumn{2}{r}{A} & {B}"),
-        (False, "{} & {A} & {A} & {B}"),
+        (True, "{} & \\multicolumn{2}{r}{A} & {B}", True),
+        (False, "{} & {A} & {A} & {B}", True),
+        (True, " & \\multicolumn{2}{r}{A} & B", False),
+        (False, " & A & A & B", False),
     ],
 )
-def test_longtable_multiindex_columns(df, sparse, exp):
+def test_longtable_multiindex_columns(df, sparse, exp, siunitx):
     cidx = MultiIndex.from_tuples([("A", "a"), ("A", "b"), ("B", "c")])
     df.columns = cidx
+    with_si = "{} & {a} & {b} & {c} \\\\"
+    without_si = " & a & b & c \\\\"
     expected = dedent(
         f"""\
-        \\begin{{longtable}}{{lrrl}}
+        \\begin{{longtable}}{{l{"SS" if siunitx else "rr"}l}}
         {exp} \\\\
-        {{}} & {{a}} & {{b}} & {{c}} \\\\
+        {with_si if siunitx else without_si}
         \\endfirsthead
         {exp} \\\\
-        {{}} & {{a}} & {{b}} & {{c}} \\\\
+        {with_si if siunitx else without_si}
         \\endhead
         """
     )
-    assert expected in df.style.to_latex(environment="longtable", sparse_columns=sparse)
+    result = df.style.to_latex(
+        environment="longtable", sparse_columns=sparse, siunitx=siunitx
+    )
+    assert expected in result
 
 
 @pytest.mark.parametrize(
@@ -660,7 +667,7 @@ def test_longtable_caption_label(styler, caption, cap_exp, label, lab_exp):
     expected = dedent(
         f"""\
         {cap_exp1}{lab_exp} \\\\
-        {{}} & {{A}} & {{B}} & {{C}} \\\\
+         & A & B & C \\\\
         \\endfirsthead
         {cap_exp2} \\\\
         """
@@ -671,8 +678,15 @@ def test_longtable_caption_label(styler, caption, cap_exp, label, lab_exp):
 
 
 @pytest.mark.parametrize("index", [True, False])
-@pytest.mark.parametrize("columns", [True, False])
-def test_apply_map_header_render_mi(df, index, columns):
+@pytest.mark.parametrize(
+    "columns, siunitx",
+    [
+        (True, True),
+        (True, False),
+        (False, False),
+    ],
+)
+def test_apply_map_header_render_mi(df, index, columns, siunitx):
     cidx = MultiIndex.from_tuples([("Z", "a"), ("Z", "b"), ("Y", "c")])
     ridx = MultiIndex.from_tuples([("A", "a"), ("A", "b"), ("B", "c")])
     df.loc[2, :] = [2, -2.22, "de"]
@@ -687,7 +701,7 @@ def test_apply_map_header_render_mi(df, index, columns):
     if columns:
         styler.applymap_index(func, axis="columns")
 
-    result = styler.to_latex()
+    result = styler.to_latex(siunitx=siunitx)
 
     expected_index = dedent(
         """\
@@ -698,13 +712,17 @@ def test_apply_map_header_render_mi(df, index, columns):
     )
     assert (expected_index in result) is index
 
-    expected_columns = dedent(
+    exp_cols_si = dedent(
         """\
     {} & {} & \\multicolumn{2}{r}{\\bfseries{Z}} & {Y} \\\\
     {} & {} & {a} & {b} & {\\bfseries{c}} \\\\
     """
     )
-    assert (expected_columns in result) is columns
+    exp_cols_no_si = """\
+ &  & \\multicolumn{2}{r}{\\bfseries{Z}} & Y \\\\
+ &  & a & b & \\bfseries{c} \\\\
+"""
+    assert ((exp_cols_si if siunitx else exp_cols_no_si) in result) is columns
 
 
 def test_repr_option(styler):
@@ -713,3 +731,8 @@ def test_repr_option(styler):
     with option_context("styler.render.repr", "latex"):
         assert "\\begin{tabular}" in styler._repr_latex_()[:15]
         assert styler._repr_html_() is None
+
+
+def test_siunitx_basic_headers(styler):
+    assert "{} & {A} & {B} & {C} \\\\" in styler.to_latex(siunitx=True)
+    assert " & A & B & C \\\\" in styler.to_latex()  # default siunitx=False