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Merged
merged 13 commits into from
Feb 1, 2024
Merged

ENH: Add check for character limmit #57103

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20e357a
Add check for character limmit
luke396 Jan 27, 2024
74e302f
Run pre-commit
luke396 Jan 27, 2024
74f4f81
Fix test
luke396 Jan 27, 2024
d864912
Merge branch 'main' into add-character-check-to-excel-cell
luke396 Jan 27, 2024
babdf29
Fix test
luke396 Jan 27, 2024
4768089
Fix test ingnore extra warings
luke396 Jan 28, 2024
65284bb
Improve by review
luke396 Jan 28, 2024
41cad2b
Add what's new
luke396 Jan 28, 2024
5470464
Merge branch 'main' into add-character-check-to-excel-cell
luke396 Jan 29, 2024
2e79c61
Update doc/source/whatsnew/v3.0.0.rst
luke396 Jan 30, 2024
91a4bee
Merge branch 'main' into add-character-check-to-excel-cell
luke396 Jan 30, 2024
62b8b54
Improve
luke396 Jan 30, 2024
bd6a975
Change what's new
luke396 Jan 30, 2024
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4 changes: 4 additions & 0 deletions pandas/core/generic.py
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Expand Up @@ -2363,6 +2363,10 @@ def to_excel(
Once a workbook has been saved it is not possible to write further
data without rewriting the whole workbook.

Pandas will check the number of rows, columns,
and cell character count does not exceed Excel's limitations.
All other limitations must be checked by the user.

Examples
--------

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7 changes: 7 additions & 0 deletions pandas/io/excel/_base.py
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Expand Up @@ -1326,6 +1326,13 @@ def _value_with_fmt(
fmt = "0"
else:
val = str(val)
# GH#56954
if len(val) > 32767:
warnings.warn(
"String value too long, truncated to 32767 characters",
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This can potentially come from other data types, "String" may end up being confusing if that's the case. I think a more generic "Cell contents too long" is better.

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I have a quick question regarding this: should we also explore validating other data types, like float or int? The current code seems to focus solely on validating the length for specific data types. Do we need to extend these checks to other types mentioned above? Alternatively, have we conducted similar checks elsewhere, or is there a best practice that should be adhered to in this context?

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should we also explore validating other data types, like float or int?

I think Excel's limitation is specifically for strings.

Alternatively, have we conducted similar checks elsewhere, or is there a best practice that should be adhered to in this context?

When you say elsewhere, are you thinking of outside the excel code? I do not know of any formal best practice.

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I believe I grasp your perspective. I want to ensure we deliberate on whether we should also account for the length of other data types. For now, let's concentrate on checking the length specifically for strings in this pull request; that should suffice.

UserWarning,
stacklevel=find_stack_level(),
)

return val, fmt

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11 changes: 11 additions & 0 deletions pandas/tests/io/excel/test_writers.py
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Expand Up @@ -1385,6 +1385,17 @@ def test_to_excel_empty_frame(self, engine, ext):
expected = DataFrame()
tm.assert_frame_equal(result, expected)

def test_to_excel_raising_warning_when_cell_character_exceed_limit(
self, path, engine
):
# GH#56954
df = DataFrame({"A": ["a" * 32768]})
msg = "String value too long, truncated to 32767 characters"
with tm.assert_produces_warning(
UserWarning, match=msg, raise_on_extra_warnings=False
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What extra warning is raised here?

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From commit babdf29,

the check https://github.com/pandas-dev/pandas/actions/runs/7678882560/job/20929191559 rise pandas/tests/io/excel/test_writers.py::TestExcelWriter::test_to_excel_raising_warning_when_cell_character_exceed_limit[openpyxl-.xlsx] - AssertionError: Caused unexpected warning(s): [('EncodingWarning', EncodingWarning("'encoding' argument not specified"), '/home/runner/micromamba/envs/test/lib/python3.10/site-packages/openpyxl/writer/excel.py', 199)]

and check https://github.com/pandas-dev/pandas/actions/runs/7678882560/job/20929192274 rasie pandas/tests/io/excel/test_writers.py::TestExcelWriter::test_to_excel_raising_warning_when_cell_character_exceed_limit[openpyxl-.xlsm] - AssertionError: Caused unexpected warning(s): [('DeprecationWarning', DeprecationWarning('datetime.datetime.utcnow() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.datetime.now(datetime.UTC).'), '/home/runner/micromamba/envs/test/lib/python3.12/site-packages/openpyxl/packaging/core.py', 99), ('DeprecationWarning', DeprecationWarning('datetime.datetime.utcnow() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.datetime.now(datetime.UTC).'), '/home/runner/micromamba/envs/test/lib/python3.12/site-packages/openpyxl/writer/excel.py', 292)]

pandas/tests/io/excel/test_writers.py::TestExcelWriter::test_to_excel_raising_warning_when_cell_character_exceed_limit is what we added in this pr. I just wrote the test following the other's in same file. If there is a better way to avoid these extra warnings, I am very happy to change codes!

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Gotcha. Yeah since these are external warnings this is fine for now

):
df.to_excel(path, engine=engine)


class TestExcelWriterEngineTests:
@pytest.mark.parametrize(
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