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BUG: Python Parser skipping over items if BOM present in first element of header #36365

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Merged
merged 6 commits into from
Sep 19, 2020
Merged

BUG: Python Parser skipping over items if BOM present in first element of header #36365

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77b9cdc
add failing test
asishm Sep 14, 2020
3ab5760
bugfix + black
asishm Sep 14, 2020
a38538b
Merge branch 'master' of github.com:pandas-dev/pandas into python_par…
asishm Sep 18, 2020
66bccdd
slight refactor
asishm Sep 18, 2020
72c9b2c
add whatsnew
asishm Sep 18, 2020
891e8d4
make separate test case
asishm Sep 19, 2020
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2 changes: 1 addition & 1 deletion pandas/io/parsers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2876,7 +2876,7 @@ def _check_for_bom(self, first_row):
return [new_row] + first_row[1:]

elif len(first_row_bom) > 1:
return [first_row_bom[1:]]
return [first_row_bom[1:]] + first_row[1:]
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Hmm I don't find this very clear why we would do this - can you try refactoring the code above this to better suit the requirement?

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from what I understand
the code block above removes the BOM from the first element of the row and removes the quotes if it was a quoted string. i.e. if it was of the format <BOM><QUOTE>abc<QUOTE>def then it extracts out abcdef

I've tried to refactor it slightly

else:
# First row is just the BOM, so we
# return an empty string.
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6 changes: 6 additions & 0 deletions pandas/tests/io/parser/test_common.py
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Expand Up @@ -2127,6 +2127,12 @@ def test_first_row_bom(all_parsers):
expected = DataFrame(columns=["Head1", "Head2", "Head3"])
tm.assert_frame_equal(result, expected)

# see gh-36343
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can you make this a new test

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done, I think test failures are unrelated. https://dev.azure.com/pandas-dev/pandas/_build/results?buildId=42772&view=ms.vss-test-web.build-test-results-tab&runId=2173848&resultId=150762&paneView=debug

data = """\ufeffHead1 Head2 Head3"""

result = parser.read_csv(StringIO(data), delimiter="\t")
tm.assert_frame_equal(result, expected)


def test_integer_precision(all_parsers):
# Gh 7072
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