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read_excel() modifies provided types dict when accessing file with duplicate column #42508

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Merged
merged 17 commits into from
Aug 4, 2021
Merged

read_excel() modifies provided types dict when accessing file with duplicate column #42508

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cf40fb3
BUG: read excel changes dtype param
debnathshoham Jul 12, 2021
a45535c
BUG: read excel changes dtype param
debnathshoham Jul 12, 2021
6c98fa3
BUG: added xlsb
debnathshoham Jul 12, 2021
e79e9a1
amended test
debnathshoham Jul 13, 2021
c10b931
modified as suggested
debnathshoham Jul 13, 2021
4419146
suggested edits
debnathshoham Jul 17, 2021
b63aef2
checked for str
debnathshoham Jul 17, 2021
f0f3022
removed updation of dtype dict from c parser
debnathshoham Jul 18, 2021
cf27280
included dtype conversion of mangled cols in c parser
debnathshoham Jul 18, 2021
52c9bd5
Merge branch 'master' into read-excel-bug-dtype
debnathshoham Jul 25, 2021
0f78c9f
Revert "removed updation of dtype dict from c parser"
debnathshoham Jul 30, 2021
cb369bb
Revert "included dtype conversion of mangled cols in c parser"
debnathshoham Jul 30, 2021
7bcb504
Revert "checked for str"
debnathshoham Jul 30, 2021
ffb5852
changed refernce to issue in test
debnathshoham Jul 31, 2021
72d50f4
reverted changes
debnathshoham Jul 31, 2021
57c65e5
added whatsnew 1.3.2
debnathshoham Aug 4, 2021
3df5cf3
Merge branch 'master' into read-excel-bug-dtype
debnathshoham Aug 4, 2021
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31 changes: 6 additions & 25 deletions pandas/io/excel/_base.py
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Original file line number Diff line number Diff line change
Expand Up @@ -358,6 +358,10 @@ def read_excel(
mangle_dupe_cols=True,
storage_options: StorageOptions = None,
):
kwargs = locals().copy()
for each in kwargs:
if isinstance(locals()[each], dict):
kwargs[each] = locals()[each].copy()
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This is essentially trying to do a deepcopy?

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Hi @mzeitlin11 . Yes it is. I tried to use deepcopy first, but it was failing multiple tests.

I got the idea of creating a copy of kwargs from read_csv (which as you mentioned doesn't produce this unnecessary side effect). So I thought it would be a good idea to keep it consistent.

pandas/pandas/io/parsers/readers.py

Lines 566 to 586 in d60e687

# locals() should never be modified
kwds = locals().copy()
del kwds["filepath_or_buffer"]
del kwds["sep"]
kwds_defaults = _refine_defaults_read(
dialect,
delimiter,
delim_whitespace,
engine,
sep,
error_bad_lines,
warn_bad_lines,
on_bad_lines,
names,
prefix,
defaults={"delimiter": ","},
)
kwds.update(kwds_defaults)
return _read(filepath_or_buffer, kwds)

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I got the idea of creating a copy of kwargs from read_csv (which as you mentioned doesn't produce this unnecessary side effect). So I thought it would be a good idea to keep it consistent.

Makes sense. That case is a bit different though because kwargs itself was being modified. Here the issue is limited to the dtypes dict. If there's a clean way to copy (or not modify in place) the dtypes dict, I think that would be cleaner.

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Sure. I will work along those lines. Thanks!

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Let me know if you run into any issues!


should_close = False
if not isinstance(io, ExcelFile):
Expand All @@ -369,32 +373,9 @@ def read_excel(
"an ExcelFile - ExcelFile already has the engine set"
)

del kwargs["io"], kwargs["engine"], kwargs["storage_options"]
try:
data = io.parse(
sheet_name=sheet_name,
header=header,
names=names,
index_col=index_col,
usecols=usecols,
squeeze=squeeze,
dtype=dtype,
converters=converters,
true_values=true_values,
false_values=false_values,
skiprows=skiprows,
nrows=nrows,
na_values=na_values,
keep_default_na=keep_default_na,
na_filter=na_filter,
verbose=verbose,
parse_dates=parse_dates,
date_parser=date_parser,
thousands=thousands,
comment=comment,
skipfooter=skipfooter,
convert_float=convert_float,
mangle_dupe_cols=mangle_dupe_cols,
)
data = io.parse(**kwargs)
finally:
# make sure to close opened file handles
if should_close:
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Binary file added pandas/tests/io/data/excel/test_common_headers.ods
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Binary file added pandas/tests/io/data/excel/test_common_headers.xls
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Binary file added pandas/tests/io/data/excel/test_common_headers.xlsb
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Binary file added pandas/tests/io/data/excel/test_common_headers.xlsm
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Binary file added pandas/tests/io/data/excel/test_common_headers.xlsx
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7 changes: 7 additions & 0 deletions pandas/tests/io/excel/test_readers.py
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Expand Up @@ -1278,6 +1278,13 @@ def test_ignore_chartsheets_by_int(self, request, read_ext):
):
pd.read_excel("chartsheet" + read_ext, sheet_name=1)

def test_dtype_dict(self, read_ext):
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Can you please leave a link to the relevant github issue here? And maybe also make the name of this test more specific, eg in this care we about about dtype argument not being modified in the case of duplicate columns being present

filename = "test_common_headers" + read_ext
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can you not use existing data? or simply do a round trip; i don't want to add even more files like this

dtype_dict = {"a": str, "b": str, "c": str}
dtype_dict_copy = dtype_dict.copy()
pd.read_excel(filename, dtype=dtype_dict)
assert dtype_dict == dtype_dict_copy, "dtype dict changed"
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Can we also check that the resulting frame is as expected? (I know this is focusing on the dtypes dict, but may as well also test the reading portion here since unlikely we have great coverage for dtypes dict with duplicate cols)



class TestExcelFileRead:
@pytest.fixture(autouse=True)
Expand Down