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File Content: `test_converters.py`

"""
Tests column conversion functionality during parsing
for all of the parsers defined in parsers.py
"""
from io import StringIO

from dateutil.parser import parse
import numpy as np
import pytest

import pandas as pd
from pandas import (
    DataFrame,
    Index,
)
import pandas._testing as tm

pytestmark = pytest.mark.usefixtures("pyarrow_skip")


def test_converters_type_must_be_dict(all_parsers):
    parser = all_parsers
    data = """index,A,B,C,D
foo,2,3,4,5
"""

    with pytest.raises(TypeError, match="Type converters.+"):
        parser.read_csv(StringIO(data), converters=0)


@pytest.mark.parametrize("column", [3, "D"])
@pytest.mark.parametrize(
    "converter", [parse, lambda x: int(x.split("/")[2])]  # Produce integer.
)
def test_converters(all_parsers, column, converter):
    parser = all_parsers
    data = """A,B,C,D
a,1,2,01/01/2009
b,3,4,01/02/2009
c,4,5,01/03/2009
"""
    result = parser.read_csv(StringIO(data), converters={column: converter})

    expected = parser.read_csv(StringIO(data))
    expected["D"] = expected["D"].map(converter)

    tm.assert_frame_equal(result, expected)


def test_converters_no_implicit_conv(all_parsers):
    # see gh-2184
    parser = all_parsers
    data = """000102,1.2,A\n001245,2,B"""

    converters = {0: lambda x: x.strip()}
    result = parser.read_csv(StringIO(data), header=None, converters=converters)

    # Column 0 should not be casted to numeric and should remain as object.
    expected = DataFrame([["000102", 1.2, "A"], ["001245", 2, "B"]])
    tm.assert_frame_equal(result, expected)


def test_converters_euro_decimal_format(all_parsers):
    # see gh-583
    converters = {}
    parser = all_parsers

    data = """Id;Number1;Number2;Text1;Text2;Number3
1;1521,1541;187101,9543;ABC;poi;4,7387
2;121,12;14897,76;DEF;uyt;0,3773
3;878,158;108013,434;GHI;rez;2,7356"""
    converters["Number1"] = converters["Number2"] = converters[
        "Number3"
    ] = lambda x: float(x.replace(",", "."))

    result = parser.read_csv(StringIO(data), sep=";", converters=converters)
    expected = DataFrame(
        [
            [1, 1521.1541, 187101.9543, "ABC", "poi", 4.7387],
            [2, 121.12, 14897.76, "DEF", "uyt", 0.3773],
            [3, 878.158, 108013.434, "GHI", "rez", 2.7356],
        ],
        columns=["Id", "Number1", "Number2", "Text1", "Text2", "Number3"],
    )
    tm.assert_frame_equal(result, expected)


def test_converters_corner_with_nans(all_parsers):
    parser = all_parsers
    data = """id,score,days
1,2,12
2,2-5,
3,,14+
4,6-12,2"""

    # Example converters.
    def convert_days(x):
        x = x.strip()

        if not x:
            return np.nan

        is_plus = x.endswith("+")

        if is_plus:
            x = int(x[:-1]) + 1
        else:
            x = int(x)

        return x

    def convert_days_sentinel(x):
        x = x.strip()

        if not x:
            return np.nan

        is_plus = x.endswith("+")

        if is_plus:
            x = int(x[:-1]) + 1
        else:
            x = int(x)

        return x

    def convert_score(x):
        x = x.strip()

        if not x:
            return np.nan

        if x.find("-") > 0:
            val_min, val_max = map(int, x.split("-"))
            val = 0.5 * (val_min + val_max)
        else:
            val = float(x)

        return val

    results = []

    for day_converter in [convert_days, convert_days_sentinel]:
        result = parser.read_csv(
            StringIO(data),
            converters={"score": convert_score, "days": day_converter},
            na_values=["", None],
        )
        assert pd.isna(result["days"][1])
        results.append(result)

    tm.assert_frame_equal(results[0], results[1])


@pytest.mark.parametrize("conv_f", [lambda x: x, str])
def test_converter_index_col_bug(all_parsers, conv_f):
    # see gh-1835 , GH#40589
    parser = all_parsers
    data = "A;B\n1;2\n3;4"

    rs = parser.read_csv(
        StringIO(data), sep=";", index_col="A", converters={"A": conv_f}
    )

    xp = DataFrame({"B": [2, 4]}, index=Index(["1", "3"], name="A", dtype="object"))
    tm.assert_frame_equal(rs, xp)


def test_converter_identity_object(all_parsers):
    # GH#40589
    parser = all_parsers
    data = "A,B\n1,2\n3,4"

    rs = parser.read_csv(StringIO(data), converters={"A": lambda x: x})

    xp = DataFrame({"A": ["1", "3"], "B": [2, 4]})
    tm.assert_frame_equal(rs, xp)


def test_converter_multi_index(all_parsers):
    # GH 42446
    parser = all_parsers
    data = "A,B,B\nX,Y,Z\n1,2,3"

    result = parser.read_csv(
        StringIO(data),
        header=list(range(2)),
        converters={
            ("A", "X"): np.int32,
            ("B", "Y"): np.int32,
            ("B", "Z"): np.float32,
        },
    )

    expected = DataFrame(
        {
            ("A", "X"): np.int32([1]),
            ("B", "Y"): np.int32([2]),
            ("B", "Z"): np.float32([3]),
        }
    )

    tm.assert_frame_equal(result, expected)

Name	Size	Permission
__pycache__	---	2755
common	---	2755
dtypes	---	2755
usecols	---	2755
__init__.py	0 bytes	0644
conftest.py	8170 bytes	0644
test_c_parser_only.py	22065 bytes	0644
test_comment.py	4824 bytes	0644
test_compression.py	6428 bytes	0644
test_concatenate_chunks.py	1128 bytes	0644
test_converters.py	4983 bytes	0644
test_dialect.py	4292 bytes	0644
test_encoding.py	9772 bytes	0644
test_header.py	17953 bytes	0644
test_index_col.py	10252 bytes	0644
test_mangle_dupes.py	4630 bytes	0644
test_multi_thread.py	3776 bytes	0644
test_na_values.py	16715 bytes	0644
test_network.py	11818 bytes	0644
test_parse_dates.py	65226 bytes	0644
test_python_parser_only.py	14097 bytes	0644
test_quoting.py	5481 bytes	0644
test_read_fwf.py	28952 bytes	0644
test_skiprows.py	7845 bytes	0644
test_textreader.py	10651 bytes	0644
test_unsupported.py	7422 bytes	0644
test_upcast.py	3289 bytes	0644

File Content: test_converters.py

File Content: `test_converters.py`