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BUG: regression in read_csv parser handling of usecols GH5766 #5770

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2 commits merged into from Dec 25, 2013
Merged

BUG: regression in read_csv parser handling of usecols GH5766 #5770

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1509a22
TST: corner_case for read_csv with usecols GH5766
wrenoud Dec 25, 2013
5e6e590
BUG: regression in read_csv parser handling of usecols GH5766
Dec 25, 2013
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10 changes: 10 additions & 0 deletions pandas/io/tests/test_parsers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2049,6 +2049,16 @@ def test_usecols(self):
header=None, usecols=['b', 'c'])
tm.assert_frame_equal(result2, result)


# 5766
result = self.read_csv(StringIO(data), names=['a', 'b'],
header=None, usecols=[0, 1])

expected = self.read_csv(StringIO(data), names=['a', 'b', 'c'],
header=None)
expected = expected[['a', 'b']]
tm.assert_frame_equal(result, expected)

# length conflict, passed names and usecols disagree
self.assertRaises(ValueError, self.read_csv, StringIO(data),
names=['a', 'b'], usecols=[1], header=None)
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3 changes: 3 additions & 0 deletions pandas/parser.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -898,6 +898,9 @@ cdef class TextReader:
if i < self.leading_cols:
# Pass through leading columns always
name = i
elif self.usecols and nused == len(self.usecols):
# Once we've gathered all requested columns, stop. GH5766
break
else:
name = self._get_column_name(i, nused)
if self.has_usecols and not (i in self.usecols or
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