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ENH: Implement cross method for Merge Operations (#37864)
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Original file line number | Diff line number | Diff line change |
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import pytest | ||
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from pandas import DataFrame | ||
import pandas._testing as tm | ||
from pandas.core.reshape.merge import MergeError, merge | ||
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@pytest.mark.parametrize( | ||
("input_col", "output_cols"), [("b", ["a", "b"]), ("a", ["a_x", "a_y"])] | ||
) | ||
def test_merge_cross(input_col, output_cols): | ||
# GH#5401 | ||
left = DataFrame({"a": [1, 3]}) | ||
right = DataFrame({input_col: [3, 4]}) | ||
left_copy = left.copy() | ||
right_copy = right.copy() | ||
result = merge(left, right, how="cross") | ||
expected = DataFrame({output_cols[0]: [1, 1, 3, 3], output_cols[1]: [3, 4, 3, 4]}) | ||
tm.assert_frame_equal(result, expected) | ||
tm.assert_frame_equal(left, left_copy) | ||
tm.assert_frame_equal(right, right_copy) | ||
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@pytest.mark.parametrize( | ||
"kwargs", | ||
[ | ||
{"left_index": True}, | ||
{"right_index": True}, | ||
{"on": "a"}, | ||
{"left_on": "a"}, | ||
{"right_on": "b"}, | ||
], | ||
) | ||
def test_merge_cross_error_reporting(kwargs): | ||
# GH#5401 | ||
left = DataFrame({"a": [1, 3]}) | ||
right = DataFrame({"b": [3, 4]}) | ||
msg = ( | ||
"Can not pass on, right_on, left_on or set right_index=True or " | ||
"left_index=True" | ||
) | ||
with pytest.raises(MergeError, match=msg): | ||
merge(left, right, how="cross", **kwargs) | ||
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def test_merge_cross_mixed_dtypes(): | ||
# GH#5401 | ||
left = DataFrame(["a", "b", "c"], columns=["A"]) | ||
right = DataFrame(range(2), columns=["B"]) | ||
result = merge(left, right, how="cross") | ||
expected = DataFrame({"A": ["a", "a", "b", "b", "c", "c"], "B": [0, 1, 0, 1, 0, 1]}) | ||
tm.assert_frame_equal(result, expected) | ||
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def test_merge_cross_more_than_one_column(): | ||
# GH#5401 | ||
left = DataFrame({"A": list("ab"), "B": [2, 1]}) | ||
right = DataFrame({"C": range(2), "D": range(4, 6)}) | ||
result = merge(left, right, how="cross") | ||
expected = DataFrame( | ||
{ | ||
"A": ["a", "a", "b", "b"], | ||
"B": [2, 2, 1, 1], | ||
"C": [0, 1, 0, 1], | ||
"D": [4, 5, 4, 5], | ||
} | ||
) | ||
tm.assert_frame_equal(result, expected) | ||
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def test_merge_cross_null_values(nulls_fixture): | ||
# GH#5401 | ||
left = DataFrame({"a": [1, nulls_fixture]}) | ||
right = DataFrame({"b": ["a", "b"], "c": [1.0, 2.0]}) | ||
result = merge(left, right, how="cross") | ||
expected = DataFrame( | ||
{ | ||
"a": [1, 1, nulls_fixture, nulls_fixture], | ||
"b": ["a", "b", "a", "b"], | ||
"c": [1.0, 2.0, 1.0, 2.0], | ||
} | ||
) | ||
tm.assert_frame_equal(result, expected) | ||
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def test_join_cross_error_reporting(): | ||
# GH#5401 | ||
left = DataFrame({"a": [1, 3]}) | ||
right = DataFrame({"a": [3, 4]}) | ||
msg = ( | ||
"Can not pass on, right_on, left_on or set right_index=True or " | ||
"left_index=True" | ||
) | ||
with pytest.raises(MergeError, match=msg): | ||
left.join(right, how="cross", on="a") |