To latex position (#35284)

Author: SylvainLan

pandas/core/generic.py

@@ -2840,6 +2840,7 @@ def to_latex(
         multirow=None,
         caption=None,
         label=None,
+        position=None,
     ):
         r"""
         Render object to a LaTeX tabular, longtable, or nested table/tabular.
@@ -2925,6 +2926,9 @@ def to_latex(
             This is used with ``\ref{}`` in the main ``.tex`` file.
 
             .. versionadded:: 1.0.0
+        position : str, optional
+            The LaTeX positional argument for tables, to be placed after
+            ``\begin{}`` in the output.
         %(returns)s
         See Also
         --------
@@ -2986,6 +2990,7 @@ def to_latex(
             multirow=multirow,
             caption=caption,
             label=label,
+            position=position,
         )
 
     def to_csv(

pandas/io/formats/format.py

@@ -931,6 +931,7 @@ def to_latex(
         multirow: bool = False,
         caption: Optional[str] = None,
         label: Optional[str] = None,
+        position: Optional[str] = None,
     ) -> Optional[str]:
         """
         Render a DataFrame to a LaTeX tabular/longtable environment output.
@@ -946,6 +947,7 @@ def to_latex(
             multirow=multirow,
             caption=caption,
             label=label,
+            position=position,
         ).get_result(buf=buf, encoding=encoding)
 
     def _format_col(self, i: int) -> List[str]:

pandas/io/formats/latex.py

@@ -38,6 +38,7 @@ def __init__(
         multirow: bool = False,
         caption: Optional[str] = None,
         label: Optional[str] = None,
+        position: Optional[str] = None,
     ):
         self.fmt = formatter
         self.frame = self.fmt.frame
@@ -50,6 +51,8 @@ def __init__(
         self.caption = caption
         self.label = label
         self.escape = self.fmt.escape
+        self.position = position
+        self._table_float = any(p is not None for p in (caption, label, position))
 
     def write_result(self, buf: IO[str]) -> None:
         """
@@ -284,7 +287,7 @@ def _write_tabular_begin(self, buf, column_format: str):
             <https://en.wikibooks.org/wiki/LaTeX/Tables>`__ e.g 'rcl'
             for 3 columns
         """
-        if self.caption is not None or self.label is not None:
+        if self._table_float:
             # then write output in a nested table/tabular environment
             if self.caption is None:
                 caption_ = ""
@@ -296,7 +299,12 @@ def _write_tabular_begin(self, buf, column_format: str):
             else:
                 label_ = f"\n\\label{{{self.label}}}"
 
-            buf.write(f"\\begin{{table}}\n\\centering{caption_}{label_}\n")
+            if self.position is None:
+                position_ = ""
+            else:
+                position_ = f"[{self.position}]"
+
+            buf.write(f"\\begin{{table}}{position_}\n\\centering{caption_}{label_}\n")
         else:
             # then write output only in a tabular environment
             pass
@@ -317,7 +325,7 @@ def _write_tabular_end(self, buf):
         """
         buf.write("\\bottomrule\n")
         buf.write("\\end{tabular}\n")
-        if self.caption is not None or self.label is not None:
+        if self._table_float:
             buf.write("\\end{table}\n")
         else:
             pass
@@ -337,25 +345,29 @@ def _write_longtable_begin(self, buf, column_format: str):
             <https://en.wikibooks.org/wiki/LaTeX/Tables>`__ e.g 'rcl'
             for 3 columns
         """
-        buf.write(f"\\begin{{longtable}}{{{column_format}}}\n")
+        if self.caption is None:
+            caption_ = ""
+        else:
+            caption_ = f"\\caption{{{self.caption}}}"
 
-        if self.caption is not None or self.label is not None:
-            if self.caption is None:
-                pass
-            else:
-                buf.write(f"\\caption{{{self.caption}}}")
+        if self.label is None:
+            label_ = ""
+        else:
+            label_ = f"\\label{{{self.label}}}"
 
-            if self.label is None:
-                pass
-            else:
-                buf.write(f"\\label{{{self.label}}}")
+        if self.position is None:
+            position_ = ""
+        else:
+            position_ = f"[{self.position}]"
 
+        buf.write(
+            f"\\begin{{longtable}}{position_}{{{column_format}}}\n{caption_}{label_}"
+        )
+        if self.caption is not None or self.label is not None:
             # a double-backslash is required at the end of the line
             # as discussed here:
             # https://tex.stackexchange.com/questions/219138
             buf.write("\\\\\n")
-        else:
-            pass
 
     @staticmethod
     def _write_longtable_end(buf):

pandas/tests/io/formats/test_to_latex.py

@@ -573,6 +573,54 @@ def test_to_latex_longtable_caption_label(self):
 """
         assert result_cl == expected_cl
 
+    def test_to_latex_position(self):
+        the_position = "h"
+
+        df = DataFrame({"a": [1, 2], "b": ["b1", "b2"]})
+
+        # test when only the position is provided
+        result_p = df.to_latex(position=the_position)
+
+        expected_p = r"""\begin{table}[h]
+\centering
+\begin{tabular}{lrl}
+\toprule
+{} &  a &   b \\
+\midrule
+0 &  1 &  b1 \\
+1 &  2 &  b2 \\
+\bottomrule
+\end{tabular}
+\end{table}
+"""
+        assert result_p == expected_p
+
+    def test_to_latex_longtable_position(self):
+        the_position = "t"
+
+        df = DataFrame({"a": [1, 2], "b": ["b1", "b2"]})
+
+        # test when only the position is provided
+        result_p = df.to_latex(longtable=True, position=the_position)
+
+        expected_p = r"""\begin{longtable}[t]{lrl}
+\toprule
+{} &  a &   b \\
+\midrule
+\endhead
+\midrule
+\multicolumn{3}{r}{{Continued on next page}} \\
+\midrule
+\endfoot
+
+\bottomrule
+\endlastfoot
+0 &  1 &  b1 \\
+1 &  2 &  b2 \\
+\end{longtable}
+"""
+        assert result_p == expected_p
+
     def test_to_latex_escape_special_chars(self):
         special_characters = ["&", "%", "$", "#", "_", "{", "}", "~", "^", "\\"]
         df = DataFrame(data=special_characters)