ENH: Styler.to_string (#44502)

Author: attack68

doc/source/reference/style.rst

@@ -27,6 +27,7 @@ Styler properties
    Styler.template_html_style
    Styler.template_html_table
    Styler.template_latex
+   Styler.template_string
    Styler.loader
 
 Style application
@@ -74,5 +75,6 @@ Style export and import
    Styler.to_html
    Styler.to_latex
    Styler.to_excel
+   Styler.to_string
    Styler.export
    Styler.use

doc/source/whatsnew/v1.5.0.rst

@@ -14,10 +14,12 @@ including other versions of pandas.
 Enhancements
 ~~~~~~~~~~~~
 
-.. _whatsnew_150.enhancements.enhancement1:
+.. _whatsnew_150.enhancements.styler:
 
-enhancement1
-^^^^^^^^^^^^
+Styler
+^^^^^^
+
+  - New method :meth:`.Styler.to_string` for alternative customisable output methods (:issue:`44502`)
 
 .. _whatsnew_150.enhancements.enhancement2:
 

pandas/io/formats/style.py

@@ -1190,6 +1190,73 @@ def to_html(
             html, buf=buf, encoding=(encoding if buf is not None else None)
         )
 
+    def to_string(
+        self,
+        buf=None,
+        *,
+        encoding=None,
+        sparse_index: bool | None = None,
+        sparse_columns: bool | None = None,
+        max_rows: int | None = None,
+        max_columns: int | None = None,
+        delimiter: str = " ",
+    ):
+        """
+        Write Styler to a file, buffer or string in text format.
+
+        .. versionadded:: 1.5.0
+
+        Parameters
+        ----------
+        buf : str, Path, or StringIO-like, optional, default None
+            Buffer to write to. If ``None``, the output is returned as a string.
+        encoding : str, optional
+            Character encoding setting for file output.
+            Defaults to ``pandas.options.styler.render.encoding`` value of "utf-8".
+        sparse_index : bool, optional
+            Whether to sparsify the display of a hierarchical index. Setting to False
+            will display each explicit level element in a hierarchical key for each row.
+            Defaults to ``pandas.options.styler.sparse.index`` value.
+        sparse_columns : bool, optional
+            Whether to sparsify the display of a hierarchical index. Setting to False
+            will display each explicit level element in a hierarchical key for each
+            column. Defaults to ``pandas.options.styler.sparse.columns`` value.
+        max_rows : int, optional
+            The maximum number of rows that will be rendered. Defaults to
+            ``pandas.options.styler.render.max_rows``, which is None.
+        max_columns : int, optional
+            The maximum number of columns that will be rendered. Defaults to
+            ``pandas.options.styler.render.max_columns``, which is None.
+
+            Rows and columns may be reduced if the number of total elements is
+            large. This value is set to ``pandas.options.styler.render.max_elements``,
+            which is 262144 (18 bit browser rendering).
+        delimiter : str, default single space
+            The separator between data elements.
+
+        Returns
+        -------
+        str or None
+            If `buf` is None, returns the result as a string. Otherwise returns `None`.
+        """
+        obj = self._copy(deepcopy=True)
+
+        if sparse_index is None:
+            sparse_index = get_option("styler.sparse.index")
+        if sparse_columns is None:
+            sparse_columns = get_option("styler.sparse.columns")
+
+        text = obj._render_string(
+            sparse_columns=sparse_columns,
+            sparse_index=sparse_index,
+            max_rows=max_rows,
+            max_cols=max_columns,
+            delimiter=delimiter,
+        )
+        return save_to_buffer(
+            text, buf=buf, encoding=(encoding if buf is not None else None)
+        )
+
     def set_td_classes(self, classes: DataFrame) -> Styler:
         """
         Set the DataFrame of strings added to the ``class`` attribute of ``<td>``

pandas/io/formats/style_render.py

@@ -74,6 +74,7 @@ class StylerRenderer:
     template_html_table = _gl01_adjust(env.get_template("html_table.tpl"))
     template_html_style = _gl01_adjust(env.get_template("html_style.tpl"))
     template_latex = _gl01_adjust(env.get_template("latex.tpl"))
+    template_string = _gl01_adjust(env.get_template("string.tpl"))
 
     def __init__(
         self,
@@ -183,6 +184,24 @@ def _render_latex(
         d.update(kwargs)
         return self.template_latex.render(**d)
 
+    def _render_string(
+        self,
+        sparse_index: bool,
+        sparse_columns: bool,
+        max_rows: int | None = None,
+        max_cols: int | None = None,
+        **kwargs,
+    ) -> str:
+        """
+        Render a Styler in string format
+        """
+        self._compute()
+
+        d = self._translate(sparse_index, sparse_columns, max_rows, max_cols, blank="")
+
+        d.update(kwargs)
+        return self.template_string.render(**d)
+
     def _compute(self):
         """
         Execute the style functions built up in `self._todo`.

pandas/io/formats/templates/string.tpl

@@ -0,0 +1,12 @@
+{% for r in head %}
+{% for c in r %}{% if c["is_visible"] %}
+{{ c["display_value"] }}{% if not loop.last %}{{ delimiter }}{% endif %}
+{% endif %}{% endfor %}
+
+{% endfor %}
+{% for r in body %}
+{% for c in r %}{% if c["is_visible"] %}
+{{ c["display_value"] }}{% if not loop.last %}{{ delimiter }}{% endif %}
+{% endif %}{% endfor %}
+
+{% endfor %}

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

@@ -0,0 +1,42 @@
+from textwrap import dedent
+
+import pytest
+
+from pandas import DataFrame
+
+pytest.importorskip("jinja2")
+from pandas.io.formats.style import Styler
+
+
+@pytest.fixture
+def df():
+    return DataFrame({"A": [0, 1], "B": [-0.61, -1.22], "C": ["ab", "cd"]})
+
+
+@pytest.fixture
+def styler(df):
+    return Styler(df, uuid_len=0, precision=2)
+
+
+def test_basic_string(styler):
+    result = styler.to_string()
+    expected = dedent(
+        """\
+     A B C
+    0 0 -0.61 ab
+    1 1 -1.22 cd
+    """
+    )
+    assert result == expected
+
+
+def test_string_delimiter(styler):
+    result = styler.to_string(delimiter=";")
+    expected = dedent(
+        """\
+    ;A;B;C
+    0;0;-0.61;ab
+    1;1;-1.22;cd
+    """
+    )
+    assert result == expected