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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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1 change: 1 addition & 0 deletions doc/source/whatsnew/v1.2.0.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -318,6 +318,7 @@ I/O
- :meth:`to_csv` did not support zip compression for binary file object not having a filename (:issue:`35058`)
- :meth:`to_csv` and :meth:`read_csv` did not honor `compression` and `encoding` for path-like objects that are internally converted to file-like objects (:issue:`35677`, :issue:`26124`, and :issue:`32392`)
- :meth:`to_picke` and :meth:`read_pickle` did not support compression for file-objects (:issue:`26237`, :issue:`29054`, and :issue:`29570`)
- Bug in :meth:`read_csv` with `engine='python'` truncating data if multiple items present in first row and first element started with BOM (:issue:`36343`)

Plotting
^^^^^^^^
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10 changes: 4 additions & 6 deletions pandas/io/parsers.py
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Expand Up @@ -2886,14 +2886,12 @@ def _check_for_bom(self, first_row):
# quotation mark.
if len(first_row_bom) > end + 1:
new_row += first_row_bom[end + 1 :]
return [new_row] + first_row[1:]

elif len(first_row_bom) > 1:
return [first_row_bom[1:]]
else:
# First row is just the BOM, so we
# return an empty string.
return [""]

# No quotation so just remove BOM from first element
new_row = first_row_bom[1:]
return [new_row] + first_row[1:]

def _is_line_empty(self, line):
"""
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10 changes: 10 additions & 0 deletions pandas/tests/io/parser/test_common.py
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Expand Up @@ -2128,6 +2128,16 @@ def test_first_row_bom(all_parsers):
tm.assert_frame_equal(result, expected)


def test_first_row_bom_unquoted(all_parsers):
# 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

parser = all_parsers
data = """\ufeffHead1 Head2 Head3"""

result = parser.read_csv(StringIO(data), delimiter="\t")
expected = DataFrame(columns=["Head1", "Head2", "Head3"])
tm.assert_frame_equal(result, expected)


def test_integer_precision(all_parsers):
# Gh 7072
s = """1,1;0;0;0;1;1;3844;3844;3844;1;1;1;1;1;1;0;0;1;1;0;0,,,4321583677327450765
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