225 lines
6.7 KiB
Python
225 lines
6.7 KiB
Python
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"""
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Tests that the specified index column (a.k.a "index_col")
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is properly handled or inferred during parsing for all of
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the parsers defined in parsers.py
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"""
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from io import StringIO
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import numpy as np
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import pytest
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from pandas import DataFrame, Index, MultiIndex
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import pandas._testing as tm
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@pytest.mark.parametrize("with_header", [True, False])
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def test_index_col_named(all_parsers, with_header):
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parser = all_parsers
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no_header = """\
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KORD1,19990127, 19:00:00, 18:56:00, 0.8100, 2.8100, 7.2000, 0.0000, 280.0000
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KORD2,19990127, 20:00:00, 19:56:00, 0.0100, 2.2100, 7.2000, 0.0000, 260.0000
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KORD3,19990127, 21:00:00, 20:56:00, -0.5900, 2.2100, 5.7000, 0.0000, 280.0000
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KORD4,19990127, 21:00:00, 21:18:00, -0.9900, 2.0100, 3.6000, 0.0000, 270.0000
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KORD5,19990127, 22:00:00, 21:56:00, -0.5900, 1.7100, 5.1000, 0.0000, 290.0000
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KORD6,19990127, 23:00:00, 22:56:00, -0.5900, 1.7100, 4.6000, 0.0000, 280.0000"""
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header = "ID,date,NominalTime,ActualTime,TDew,TAir,Windspeed,Precip,WindDir\n"
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if with_header:
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data = header + no_header
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result = parser.read_csv(StringIO(data), index_col="ID")
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expected = parser.read_csv(StringIO(data), header=0).set_index("ID")
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tm.assert_frame_equal(result, expected)
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else:
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data = no_header
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msg = "Index ID invalid"
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with pytest.raises(ValueError, match=msg):
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parser.read_csv(StringIO(data), index_col="ID")
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def test_index_col_named2(all_parsers):
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parser = all_parsers
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data = """\
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1,2,3,4,hello
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5,6,7,8,world
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9,10,11,12,foo
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"""
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expected = DataFrame(
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{"a": [1, 5, 9], "b": [2, 6, 10], "c": [3, 7, 11], "d": [4, 8, 12]},
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index=Index(["hello", "world", "foo"], name="message"),
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)
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names = ["a", "b", "c", "d", "message"]
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result = parser.read_csv(StringIO(data), names=names, index_col=["message"])
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tm.assert_frame_equal(result, expected)
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def test_index_col_is_true(all_parsers):
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# see gh-9798
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data = "a,b\n1,2"
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parser = all_parsers
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msg = "The value of index_col couldn't be 'True'"
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with pytest.raises(ValueError, match=msg):
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parser.read_csv(StringIO(data), index_col=True)
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def test_infer_index_col(all_parsers):
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data = """A,B,C
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foo,1,2,3
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bar,4,5,6
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baz,7,8,9
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"""
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parser = all_parsers
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result = parser.read_csv(StringIO(data))
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expected = DataFrame(
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[[1, 2, 3], [4, 5, 6], [7, 8, 9]],
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index=["foo", "bar", "baz"],
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columns=["A", "B", "C"],
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)
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tm.assert_frame_equal(result, expected)
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@pytest.mark.parametrize(
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"index_col,kwargs",
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[
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(None, dict(columns=["x", "y", "z"])),
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(False, dict(columns=["x", "y", "z"])),
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(0, dict(columns=["y", "z"], index=Index([], name="x"))),
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(1, dict(columns=["x", "z"], index=Index([], name="y"))),
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("x", dict(columns=["y", "z"], index=Index([], name="x"))),
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("y", dict(columns=["x", "z"], index=Index([], name="y"))),
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(
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[0, 1],
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dict(
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columns=["z"], index=MultiIndex.from_arrays([[]] * 2, names=["x", "y"])
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),
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),
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(
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["x", "y"],
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dict(
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columns=["z"], index=MultiIndex.from_arrays([[]] * 2, names=["x", "y"])
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),
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),
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(
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[1, 0],
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dict(
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columns=["z"], index=MultiIndex.from_arrays([[]] * 2, names=["y", "x"])
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),
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),
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(
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["y", "x"],
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dict(
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columns=["z"], index=MultiIndex.from_arrays([[]] * 2, names=["y", "x"])
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),
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),
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],
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)
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def test_index_col_empty_data(all_parsers, index_col, kwargs):
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data = "x,y,z"
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parser = all_parsers
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result = parser.read_csv(StringIO(data), index_col=index_col)
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expected = DataFrame(**kwargs)
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tm.assert_frame_equal(result, expected)
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def test_empty_with_index_col_false(all_parsers):
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# see gh-10413
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data = "x,y"
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parser = all_parsers
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result = parser.read_csv(StringIO(data), index_col=False)
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expected = DataFrame(columns=["x", "y"])
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tm.assert_frame_equal(result, expected)
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@pytest.mark.parametrize(
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"index_names",
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[
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["", ""],
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["foo", ""],
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["", "bar"],
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["foo", "bar"],
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["NotReallyUnnamed", "Unnamed: 0"],
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],
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)
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def test_multi_index_naming(all_parsers, index_names):
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parser = all_parsers
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# We don't want empty index names being replaced with "Unnamed: 0"
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data = ",".join(index_names + ["col\na,c,1\na,d,2\nb,c,3\nb,d,4"])
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result = parser.read_csv(StringIO(data), index_col=[0, 1])
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expected = DataFrame(
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{"col": [1, 2, 3, 4]}, index=MultiIndex.from_product([["a", "b"], ["c", "d"]])
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)
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expected.index.names = [name if name else None for name in index_names]
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tm.assert_frame_equal(result, expected)
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def test_multi_index_naming_not_all_at_beginning(all_parsers):
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parser = all_parsers
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data = ",Unnamed: 2,\na,c,1\na,d,2\nb,c,3\nb,d,4"
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result = parser.read_csv(StringIO(data), index_col=[0, 2])
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expected = DataFrame(
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{"Unnamed: 2": ["c", "d", "c", "d"]},
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index=MultiIndex(
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levels=[["a", "b"], [1, 2, 3, 4]], codes=[[0, 0, 1, 1], [0, 1, 2, 3]]
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),
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)
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tm.assert_frame_equal(result, expected)
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def test_no_multi_index_level_names_empty(all_parsers):
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# GH 10984
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parser = all_parsers
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midx = MultiIndex.from_tuples([("A", 1, 2), ("A", 1, 2), ("B", 1, 2)])
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expected = DataFrame(np.random.randn(3, 3), index=midx, columns=["x", "y", "z"])
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with tm.ensure_clean() as path:
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expected.to_csv(path)
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result = parser.read_csv(path, index_col=[0, 1, 2])
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tm.assert_frame_equal(result, expected)
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def test_header_with_index_col(all_parsers):
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# GH 33476
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parser = all_parsers
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data = """
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I11,A,A
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I12,B,B
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I2,1,3
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"""
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midx = MultiIndex.from_tuples([("A", "B"), ("A", "B.1")], names=["I11", "I12"])
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idx = Index(["I2"])
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expected = DataFrame([[1, 3]], index=idx, columns=midx)
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result = parser.read_csv(StringIO(data), index_col=0, header=[0, 1])
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tm.assert_frame_equal(result, expected)
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col_idx = Index(["A", "A.1"])
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idx = Index(["I12", "I2"], name="I11")
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expected = DataFrame([["B", "B"], ["1", "3"]], index=idx, columns=col_idx)
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result = parser.read_csv(StringIO(data), index_col="I11", header=0)
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tm.assert_frame_equal(result, expected)
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@pytest.mark.slow
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def test_index_col_large_csv(all_parsers):
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# https://github.com/pandas-dev/pandas/issues/37094
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parser = all_parsers
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N = 1_000_001
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df = DataFrame({"a": range(N), "b": np.random.randn(N)})
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with tm.ensure_clean() as path:
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df.to_csv(path, index=False)
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result = parser.read_csv(path, index_col=[0])
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tm.assert_frame_equal(result, df.set_index("a"))
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