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| """
| Tests that comments are properly handled during parsing
| for all of the parsers defined in parsers.py
| """
| from io import StringIO
|
| import numpy as np
| import pytest
|
| from pandas import DataFrame
| import pandas._testing as tm
|
| pytestmark = pytest.mark.usefixtures("pyarrow_skip")
|
|
| @pytest.mark.parametrize("na_values", [None, ["NaN"]])
| def test_comment(all_parsers, na_values):
| parser = all_parsers
| data = """A,B,C
| 1,2.,4.#hello world
| 5.,NaN,10.0
| """
| expected = DataFrame(
| [[1.0, 2.0, 4.0], [5.0, np.nan, 10.0]], columns=["A", "B", "C"]
| )
| result = parser.read_csv(StringIO(data), comment="#", na_values=na_values)
| tm.assert_frame_equal(result, expected)
|
|
| @pytest.mark.parametrize(
| "read_kwargs", [{}, {"lineterminator": "*"}, {"delim_whitespace": True}]
| )
| def test_line_comment(all_parsers, read_kwargs, request):
| parser = all_parsers
| data = """# empty
| A,B,C
| 1,2.,4.#hello world
| #ignore this line
| 5.,NaN,10.0
| """
| if read_kwargs.get("delim_whitespace"):
| data = data.replace(",", " ")
| elif read_kwargs.get("lineterminator"):
| if parser.engine != "c":
| mark = pytest.mark.xfail(
| reason="Custom terminator not supported with Python engine"
| )
| request.node.add_marker(mark)
|
| data = data.replace("\n", read_kwargs.get("lineterminator"))
|
| read_kwargs["comment"] = "#"
| result = parser.read_csv(StringIO(data), **read_kwargs)
|
| expected = DataFrame(
| [[1.0, 2.0, 4.0], [5.0, np.nan, 10.0]], columns=["A", "B", "C"]
| )
| tm.assert_frame_equal(result, expected)
|
|
| def test_comment_skiprows(all_parsers):
| parser = all_parsers
| data = """# empty
| random line
| # second empty line
| 1,2,3
| A,B,C
| 1,2.,4.
| 5.,NaN,10.0
| """
| # This should ignore the first four lines (including comments).
| expected = DataFrame(
| [[1.0, 2.0, 4.0], [5.0, np.nan, 10.0]], columns=["A", "B", "C"]
| )
| result = parser.read_csv(StringIO(data), comment="#", skiprows=4)
| tm.assert_frame_equal(result, expected)
|
|
| def test_comment_header(all_parsers):
| parser = all_parsers
| data = """# empty
| # second empty line
| 1,2,3
| A,B,C
| 1,2.,4.
| 5.,NaN,10.0
| """
| # Header should begin at the second non-comment line.
| expected = DataFrame(
| [[1.0, 2.0, 4.0], [5.0, np.nan, 10.0]], columns=["A", "B", "C"]
| )
| result = parser.read_csv(StringIO(data), comment="#", header=1)
| tm.assert_frame_equal(result, expected)
|
|
| def test_comment_skiprows_header(all_parsers):
| parser = all_parsers
| data = """# empty
| # second empty line
| # third empty line
| X,Y,Z
| 1,2,3
| A,B,C
| 1,2.,4.
| 5.,NaN,10.0
| """
| # Skiprows should skip the first 4 lines (including comments),
| # while header should start from the second non-commented line,
| # starting with line 5.
| expected = DataFrame(
| [[1.0, 2.0, 4.0], [5.0, np.nan, 10.0]], columns=["A", "B", "C"]
| )
| result = parser.read_csv(StringIO(data), comment="#", skiprows=4, header=1)
| tm.assert_frame_equal(result, expected)
|
|
| @pytest.mark.parametrize("comment_char", ["#", "~", "&", "^", "*", "@"])
| def test_custom_comment_char(all_parsers, comment_char):
| parser = all_parsers
| data = "a,b,c\n1,2,3#ignore this!\n4,5,6#ignorethistoo"
| result = parser.read_csv(
| StringIO(data.replace("#", comment_char)), comment=comment_char
| )
|
| expected = DataFrame([[1, 2, 3], [4, 5, 6]], columns=["a", "b", "c"])
| tm.assert_frame_equal(result, expected)
|
|
| @pytest.mark.parametrize("header", ["infer", None])
| def test_comment_first_line(all_parsers, header):
| # see gh-4623
| parser = all_parsers
| data = "# notes\na,b,c\n# more notes\n1,2,3"
|
| if header is None:
| expected = DataFrame({0: ["a", "1"], 1: ["b", "2"], 2: ["c", "3"]})
| else:
| expected = DataFrame([[1, 2, 3]], columns=["a", "b", "c"])
|
| result = parser.read_csv(StringIO(data), comment="#", header=header)
| tm.assert_frame_equal(result, expected)
|
|
| def test_comment_char_in_default_value(all_parsers, request):
| # GH#34002
| if all_parsers.engine == "c":
| reason = "see gh-34002: works on the python engine but not the c engine"
| # NA value containing comment char is interpreted as comment
| request.node.add_marker(pytest.mark.xfail(reason=reason, raises=AssertionError))
| parser = all_parsers
|
| data = (
| "# this is a comment\n"
| "col1,col2,col3,col4\n"
| "1,2,3,4#inline comment\n"
| "4,5#,6,10\n"
| "7,8,#N/A,11\n"
| )
| result = parser.read_csv(StringIO(data), comment="#", na_values="#N/A")
| expected = DataFrame(
| {
| "col1": [1, 4, 7],
| "col2": [2, 5, 8],
| "col3": [3.0, np.nan, np.nan],
| "col4": [4.0, np.nan, 11.0],
| }
| )
| tm.assert_frame_equal(result, expected)
|
|
