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ENH: Change DataFrame.to_excel to output unformatted excel file #54302

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Merged
merged 9 commits into from
Feb 15, 2024
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ENH: Change DataFrame.to_excel to output unformatted excel file #54302

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620dc40
Updated default styling logic for to_excel and added unit tests.
rmhowe425 Jul 29, 2023
a44242a
Adding documentation to the Pandas User Guide.
rmhowe425 Jul 29, 2023
4c04104
Merge branch 'main' into dev/to_excel/format
rmhowe425 Feb 15, 2024
ac25ee3
Updating whatsnew
rmhowe425 Feb 15, 2024
505b4a8
Fixing merge conflict.
rmhowe425 Feb 15, 2024
86662c4
Updating user guide documentation.
rmhowe425 Feb 15, 2024
024a162
Fixing syntax error.
rmhowe425 Feb 15, 2024
c1731fd
Updating implementation based on reviewer feedback.
rmhowe425 Feb 15, 2024
ebdef70
Updating documentation.
rmhowe425 Feb 15, 2024
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14 changes: 14 additions & 0 deletions doc/source/user_guide/io.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -3924,6 +3924,20 @@ The look and feel of Excel worksheets created from pandas can be modified using
* ``float_format`` : Format string for floating point numbers (default ``None``).
* ``freeze_panes`` : A tuple of two integers representing the bottommost row and rightmost column to freeze. Each of these parameters is one-based, so (1, 1) will freeze the first row and first column (default ``None``).

.. note::

As of Pandas 3.0, by default spreadsheets created with the ``to_excel`` method
will not contain any styling. Users wishing to bold text, add bordered styles,
etc in a worksheet output by ``to_excel`` can do so by using ``Styler.to_excel``
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Can you use :meth:`Styler.to_excel` and also add a reference to the section in the User Guide: https://pandas.pydata.org/docs/user_guide/style.html#Export-to-Excel

to create styled excel files.


.. code-block:: python

css = "border: 1pt solid #111222"
styler = df.style.map(lambda x: css)
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I don't think this is equivalent to how Excel files are currently styled, is that right? Would it make sense to do that instead?

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@attack68 attack68 Aug 3, 2023 •
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I agree, think we need to provide the exact replication. Typing on phone now but I suggest the its probably going to be something like;

css = "border: 1px solid black; font-weight: bold;"
# instead of df.to_excel("myfile.xlsx")
df.style.map_index(lambda x: css).map_index(lambda x: css, axis=1).to_excel("myfile.xlsx")

It might need text-align as well - I cant remember off hand.

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@attack68 Yeah doing a quick comparison of the above with a basic call to DataFrame.to_excel() shows that the above styling is the same as the current default styling.

styler.to_excel("path_to_file.xlsx", sheet_name="custom", index=False)

Using the `Xlsxwriter`_ engine provides many options for controlling the
format of an Excel worksheet created with the ``to_excel`` method. Excellent examples can be found in the
`Xlsxwriter`_ documentation here: https://xlsxwriter.readthedocs.io/working_with_pandas.html
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1 change: 1 addition & 0 deletions doc/source/whatsnew/v2.1.0.rst
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Expand Up @@ -176,6 +176,7 @@ Other enhancements
- Performance improvement in :func:`concat` with homogeneous ``np.float64`` or ``np.float32`` dtypes (:issue:`52685`)
- Performance improvement in :meth:`DataFrame.filter` when ``items`` is given (:issue:`52941`)
- Reductions :meth:`Series.argmax`, :meth:`Series.argmin`, :meth:`Series.idxmax`, :meth:`Series.idxmin`, :meth:`Index.argmax`, :meth:`Index.argmin`, :meth:`DataFrame.idxmax`, :meth:`DataFrame.idxmin` are now supported for object-dtype objects (:issue:`4279`, :issue:`18021`, :issue:`40685`, :issue:`43697`)
- Updated :meth:`DataFrame.to_excel` so that the output spreadsheet has no styling. (:issue:`54154`)
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From the issue, this change will need to happen in 3.0 not 2.1

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@mroeschke Looks like there is no whatsnew file yet for 3.0.

I can just create one by creating a template based on 2.1?

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We'll create one once we release 2.2 (in December), so let's hold on with this PR for now

-

.. ---------------------------------------------------------------------------
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33 changes: 10 additions & 23 deletions pandas/io/formats/excel.py
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Original file line number Diff line number Diff line change
Expand Up @@ -580,19 +580,6 @@ def __init__(
self.merge_cells = merge_cells
self.inf_rep = inf_rep

@property
def header_style(self) -> dict[str, dict[str, str | bool]]:
return {
"font": {"bold": True},
"borders": {
"top": "thin",
"right": "thin",
"bottom": "thin",
"left": "thin",
},
"alignment": {"horizontal": "center", "vertical": "top"},
}

def _format_value(self, val):
if is_scalar(val) and missing.isna(val):
val = self.na_rep
Expand Down Expand Up @@ -640,7 +627,7 @@ def _format_header_mi(self) -> Iterable[ExcelCell]:
row=lnum,
col=coloffset,
val=name,
style=self.header_style,
style=None,
)

for lnum, (spans, levels, level_codes) in enumerate(
Expand All @@ -655,7 +642,7 @@ def _format_header_mi(self) -> Iterable[ExcelCell]:
row=lnum,
col=coloffset + i + 1,
val=values[i],
style=self.header_style,
style=None,
css_styles=getattr(self.styler, "ctx_columns", None),
css_row=lnum,
css_col=i,
Expand All @@ -671,7 +658,7 @@ def _format_header_mi(self) -> Iterable[ExcelCell]:
row=lnum,
col=coloffset + i + 1,
val=v,
style=self.header_style,
style=None,
css_styles=getattr(self.styler, "ctx_columns", None),
css_row=lnum,
css_col=i,
Expand Down Expand Up @@ -704,7 +691,7 @@ def _format_header_regular(self) -> Iterable[ExcelCell]:
row=self.rowcounter,
col=colindex + coloffset,
val=colname,
style=self.header_style,
style=None,
css_styles=getattr(self.styler, "ctx_columns", None),
css_row=0,
css_col=colindex,
Expand All @@ -727,7 +714,7 @@ def _format_header(self) -> Iterable[ExcelCell]:
] * len(self.columns)
if functools.reduce(lambda x, y: x and y, (x != "" for x in row)):
gen2 = (
ExcelCell(self.rowcounter, colindex, val, self.header_style)
ExcelCell(self.rowcounter, colindex, val, None)
for colindex, val in enumerate(row)
)
self.rowcounter += 1
Expand Down Expand Up @@ -761,7 +748,7 @@ def _format_regular_rows(self) -> Iterable[ExcelCell]:
self.rowcounter += 1

if index_label and self.header is not False:
yield ExcelCell(self.rowcounter - 1, 0, index_label, self.header_style)
yield ExcelCell(self.rowcounter - 1, 0, index_label, None)

# write index_values
index_values = self.df.index
Expand All @@ -773,7 +760,7 @@ def _format_regular_rows(self) -> Iterable[ExcelCell]:
row=self.rowcounter + idx,
col=0,
val=idxval,
style=self.header_style,
style=None,
css_styles=getattr(self.styler, "ctx_index", None),
css_row=idx,
css_col=0,
Expand Down Expand Up @@ -809,7 +796,7 @@ def _format_hierarchical_rows(self) -> Iterable[ExcelCell]:
# if index labels are not empty go ahead and dump
if com.any_not_none(*index_labels) and self.header is not False:
for cidx, name in enumerate(index_labels):
yield ExcelCell(self.rowcounter - 1, cidx, name, self.header_style)
yield ExcelCell(self.rowcounter - 1, cidx, name, None)

if self.merge_cells:
# Format hierarchical rows as merged cells.
Expand All @@ -836,7 +823,7 @@ def _format_hierarchical_rows(self) -> Iterable[ExcelCell]:
row=self.rowcounter + i,
col=gcolidx,
val=values[i],
style=self.header_style,
style=None,
css_styles=getattr(self.styler, "ctx_index", None),
css_row=i,
css_col=gcolidx,
Expand All @@ -854,7 +841,7 @@ def _format_hierarchical_rows(self) -> Iterable[ExcelCell]:
row=self.rowcounter + idx,
col=gcolidx,
val=indexcolval,
style=self.header_style,
style=None,
css_styles=getattr(self.styler, "ctx_index", None),
css_row=idx,
css_col=gcolidx,
Expand Down
55 changes: 55 additions & 0 deletions pandas/tests/io/excel/test_style.py
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,28 @@ def assert_equal_cell_styles(cell1, cell2):
assert cell1.protection.__dict__ == cell2.protection.__dict__


def test_styler_default_values():
# GH 54154
openpyxl = pytest.importorskip("openpyxl")
df = DataFrame([{"A": 1, "B": 2, "C": 3}, {"A": 1, "B": 2, "C": 3}])

with tm.ensure_clean(".xlsx") as path:
with ExcelWriter(path, engine="openpyxl") as writer:
df.to_excel(writer, sheet_name="custom")

with contextlib.closing(openpyxl.load_workbook(path)) as wb:
# Check font, spacing, indentation
assert wb["custom"].cell(1, 1).font.bold is False
assert wb["custom"].cell(1, 1).alignment.horizontal is None
assert wb["custom"].cell(1, 1).alignment.vertical is None

# Check border
assert wb["custom"].cell(1, 1).border.bottom.color is None
assert wb["custom"].cell(1, 1).border.top.color is None
assert wb["custom"].cell(1, 1).border.left.color is None
assert wb["custom"].cell(1, 1).border.right.color is None


@pytest.mark.parametrize(
"engine",
["xlsxwriter", "openpyxl"],
Expand Down Expand Up @@ -123,6 +145,39 @@ def test_styler_to_excel_unstyled(engine):
]


@pytest.mark.parametrize(
"css",
["background-color: #111222"],
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Can you inline this in the test since it's only 1 parameter

)
def test_styler_custom_style(css):
# GH 54154
openpyxl = pytest.importorskip("openpyxl")
df = DataFrame([{"A": 1, "B": 2}, {"A": 1, "B": 2}])

with tm.ensure_clean(".xlsx") as path:
with ExcelWriter(path, engine="openpyxl") as writer:
styler = df.style.map(lambda x: css)
styler.to_excel(writer, sheet_name="custom", index=False)

with contextlib.closing(openpyxl.load_workbook(path)) as wb:
# Check font, spacing, indentation
assert wb["custom"].cell(1, 1).font.bold is False
assert wb["custom"].cell(1, 1).alignment.horizontal is None
assert wb["custom"].cell(1, 1).alignment.vertical is None

# Check border
assert wb["custom"].cell(1, 1).border.bottom.color is None
assert wb["custom"].cell(1, 1).border.top.color is None
assert wb["custom"].cell(1, 1).border.left.color is None
assert wb["custom"].cell(1, 1).border.right.color is None

# Check background color
assert wb["custom"].cell(2, 1).fill.fgColor.index == "00111222"
assert wb["custom"].cell(3, 1).fill.fgColor.index == "00111222"
assert wb["custom"].cell(2, 2).fill.fgColor.index == "00111222"
assert wb["custom"].cell(3, 2).fill.fgColor.index == "00111222"


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@weikhor weikhor Feb 6, 2024 •
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I think we can simplify code test by combining both functions test_styler_default_values and test_styler_custom_style to one function.

@pytest.mark.parametrize(
    "css, color",
    [("", "00000000"), 
     ("background-color: #111222", "00111222")],
)
def test_default_and_custom_style(css, color):
    # GH 54154
    openpyxl = pytest.importorskip("openpyxl")
    df = DataFrame([{"A": 1, "B": 2}, {"A": 1, "B": 2}])

    with tm.ensure_clean(".xlsx") as path:
        with ExcelWriter(path, engine="openpyxl") as writer:
            styler = df.style.map(lambda x: css)
            styler.to_excel(writer, sheet_name="custom", index=False)

        with contextlib.closing(openpyxl.load_workbook(path)) as wb:
            # Check font, spacing, indentation
            assert wb["custom"].cell(1, 1).font.bold is False
            assert wb["custom"].cell(1, 1).alignment.horizontal is None
            assert wb["custom"].cell(1, 1).alignment.vertical is None

            # Check border
            assert wb["custom"].cell(1, 1).border.bottom.color is None
            assert wb["custom"].cell(1, 1).border.top.color is None
            assert wb["custom"].cell(1, 1).border.left.color is None
            assert wb["custom"].cell(1, 1).border.right.color is None

            # Check background color
            assert wb["custom"].cell(2, 1).fill.fgColor.index == color
            assert wb["custom"].cell(3, 1).fill.fgColor.index == color
            assert wb["custom"].cell(2, 2).fill.fgColor.index == color
            assert wb["custom"].cell(3, 2).fill.fgColor.index == color

@pytest.mark.parametrize(
"engine",
["xlsxwriter", "openpyxl"],
Expand Down