import numpy as np
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import pytest
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import pandas as pd
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from pandas import (
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Index,
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MultiIndex,
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Series,
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)
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import pandas._testing as tm
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class TestIndexConstructor:
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# Tests for the Index constructor, specifically for cases that do
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# not return a subclass
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@pytest.mark.parametrize("value", [1, np.int64(1)])
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def test_constructor_corner(self, value):
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# corner case
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msg = (
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r"Index\(\.\.\.\) must be called with a collection of some "
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f"kind, {value} was passed"
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)
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with pytest.raises(TypeError, match=msg):
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Index(value)
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@pytest.mark.parametrize("index_vals", [[("A", 1), "B"], ["B", ("A", 1)]])
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def test_construction_list_mixed_tuples(self, index_vals):
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# see gh-10697: if we are constructing from a mixed list of tuples,
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# make sure that we are independent of the sorting order.
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index = Index(index_vals)
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assert isinstance(index, Index)
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assert not isinstance(index, MultiIndex)
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def test_constructor_cast(self):
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msg = "could not convert string to float"
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with pytest.raises(ValueError, match=msg):
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Index(["a", "b", "c"], dtype=float)
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@pytest.mark.parametrize("tuple_list", [[()], [(), ()]])
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def test_construct_empty_tuples(self, tuple_list):
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# GH #45608
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result = Index(tuple_list)
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expected = MultiIndex.from_tuples(tuple_list)
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tm.assert_index_equal(result, expected)
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def test_index_string_inference(self):
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# GH#54430
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expected = Index(["a", "b"], dtype=pd.StringDtype(na_value=np.nan))
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with pd.option_context("future.infer_string", True):
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ser = Index(["a", "b"])
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tm.assert_index_equal(ser, expected)
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expected = Index(["a", 1], dtype="object")
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with pd.option_context("future.infer_string", True):
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ser = Index(["a", 1])
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tm.assert_index_equal(ser, expected)
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def test_inference_on_pandas_objects(self):
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# GH#56012
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idx = Index([pd.Timestamp("2019-12-31")], dtype=object)
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with tm.assert_produces_warning(FutureWarning, match="Dtype inference"):
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result = Index(idx)
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assert result.dtype != np.object_
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ser = Series([pd.Timestamp("2019-12-31")], dtype=object)
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with tm.assert_produces_warning(FutureWarning, match="Dtype inference"):
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result = Index(ser)
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assert result.dtype != np.object_
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def test_constructor_not_read_only(self):
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# GH#57130
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ser = Series([1, 2], dtype=object)
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with pd.option_context("mode.copy_on_write", True):
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idx = Index(ser)
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assert idx._values.flags.writeable
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