ENH: Add index option to_markdown()

doc/source/whatsnew/v1.1.0.rst

@@ -328,6 +328,7 @@ Other enhancements
 - :meth:`DataFrame.to_html` and :meth:`DataFrame.to_string`'s ``col_space`` parameter now accepts a list or dict to change only some specific columns' width (:issue:`28917`).
 - :meth:`DataFrame.to_excel` can now also write OpenOffice spreadsheet (.ods) files (:issue:`27222`)
 - :meth:`~Series.explode` now accepts ``ignore_index`` to reset the index, similarly to :meth:`pd.concat` or :meth:`DataFrame.sort_values` (:issue:`34932`).
+- :meth:`DataFrame.to_markdown` and :meth:`Series.to_markdown` now accept ``index`` argument as an alias for tabulate's ``showindex`` (:issue:`32667`)
 - :meth:`read_csv` now accepts string values like "0", "0.0", "1", "1.0" as convertible to the nullable boolean dtype (:issue:`34859`)
 - :class:`pandas.core.window.ExponentialMovingWindow` now supports a ``times`` argument that allows ``mean`` to be calculated with observations spaced by the timestamps in ``times`` (:issue:`34839`)
 

pandas/core/frame.py

@@ -2217,10 +2217,23 @@ def to_feather(self, path, **kwargs) -> None:
         """,
     )
     def to_markdown(
-        self, buf: Optional[IO[str]] = None, mode: Optional[str] = None, **kwargs
+        self,
+        buf: Optional[IO[str]] = None,
+        mode: Optional[str] = None,
+        index: bool = True,
+        **kwargs,
     ) -> Optional[str]:
+        if "showindex" in kwargs:
+            warnings.warn(
+                "'showindex' is deprecated. Only 'index' will be used "
+                "in a future version. Use 'index' to silence this warning.",
+                FutureWarning,
+                stacklevel=2,
+            )
+
         kwargs.setdefault("headers", "keys")
         kwargs.setdefault("tablefmt", "pipe")
+        kwargs.setdefault("showindex", index)
         tabulate = import_optional_dependency("tabulate")
         result = tabulate.tabulate(self, **kwargs)
         if buf is None:

pandas/core/series.py

@@ -1419,7 +1419,11 @@ def to_string(
         ),
     )
     def to_markdown(
-        self, buf: Optional[IO[str]] = None, mode: Optional[str] = None, **kwargs
+        self,
+        buf: Optional[IO[str]] = None,
+        mode: Optional[str] = None,
+        index: bool = True,
+        **kwargs,
     ) -> Optional[str]:
         """
         Print {klass} in Markdown-friendly format.
@@ -1432,6 +1436,8 @@ def to_markdown(
             Buffer to write to. If None, the output is returned as a string.
         mode : str, optional
             Mode in which file is opened.
+        index : bool, optional, default True
+            Add index (row) labels.
         **kwargs
             These parameters will be passed to `tabulate \
                 <https://pypi.org/project/tabulate>`_.
@@ -1467,7 +1473,7 @@ def to_markdown(
         |  3 | quetzal  |
         +----+----------+
         """
-        return self.to_frame().to_markdown(buf, mode, **kwargs)
+        return self.to_frame().to_markdown(buf, mode, index, **kwargs)
 
     # ----------------------------------------------------------------------
 

pandas/tests/io/formats/test_to_markdown.py

@@ -3,6 +3,7 @@
 import pytest
 
 import pandas as pd
+import pandas._testing as tm
 
 pytest.importorskip("tabulate")
 
@@ -53,3 +54,37 @@ def test_no_buf(capsys):
     assert (
         result == "|    |   0 |\n|---:|----:|\n|  0 |   1 |\n|  1 |   2 |\n|  2 |   3 |"
     )
+
+
+@pytest.mark.parametrize("index", [True, False, None])
+@pytest.mark.parametrize("showindex", [True, False, None])
+def test_index(index, showindex):
+    # GH 32667
+    kwargs = {}
+    if index is not None:
+        kwargs["index"] = index
+    if showindex is not None:
+        kwargs["showindex"] = showindex
+
+    df = pd.DataFrame([1, 2, 3])
+    yes_index_result = (
+        "|    |   0 |\n|---:|----:|\n|  0 |   1 |\n|  1 |   2 |\n|  2 |   3 |"
+    )
+    no_index_result = "|   0 |\n|----:|\n|   1 |\n|   2 |\n|   3 |"
+
+    warning = FutureWarning if "showindex" in kwargs else None
+    with tm.assert_produces_warning(warning):
+        result = df.to_markdown(**kwargs)
+
+    if "showindex" in kwargs:
+        # give showindex higher priority if specified
+        if showindex:
+            expected = yes_index_result
+        else:
+            expected = no_index_result
+    else:
+        if index in [True, None]:
+            expected = yes_index_result
+        else:
+            expected = no_index_result
+    assert result == expected