import numpy as np
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import pytest
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from pandas.errors import SettingWithCopyError
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import pandas.util._test_decorators as td
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from pandas import (
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DataFrame,
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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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def test_detect_chained_assignment(using_copy_on_write):
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# Inplace ops, originally from:
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# https://stackoverflow.com/questions/20508968/series-fillna-in-a-multiindex-dataframe-does-not-fill-is-this-a-bug
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a = [12, 23]
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b = [123, None]
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c = [1234, 2345]
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d = [12345, 23456]
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tuples = [("eyes", "left"), ("eyes", "right"), ("ears", "left"), ("ears", "right")]
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events = {
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("eyes", "left"): a,
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("eyes", "right"): b,
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("ears", "left"): c,
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("ears", "right"): d,
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}
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multiind = MultiIndex.from_tuples(tuples, names=["part", "side"])
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zed = DataFrame(events, index=["a", "b"], columns=multiind)
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if using_copy_on_write:
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zed["eyes"]["right"].fillna(value=555, inplace=True)
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else:
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msg = "A value is trying to be set on a copy of a slice from a DataFrame"
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with pytest.raises(SettingWithCopyError, match=msg):
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zed["eyes"]["right"].fillna(value=555, inplace=True)
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@td.skip_array_manager_invalid_test # with ArrayManager df.loc[0] is not a view
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def test_cache_updating(using_copy_on_write):
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# 5216
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# make sure that we don't try to set a dead cache
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a = np.random.rand(10, 3)
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df = DataFrame(a, columns=["x", "y", "z"])
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df_original = df.copy()
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tuples = [(i, j) for i in range(5) for j in range(2)]
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index = MultiIndex.from_tuples(tuples)
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df.index = index
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# setting via chained assignment
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# but actually works, since everything is a view
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if using_copy_on_write:
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with tm.raises_chained_assignment_error():
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df.loc[0]["z"].iloc[0] = 1.0
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assert df.loc[(0, 0), "z"] == df_original.loc[0, "z"]
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else:
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df.loc[0]["z"].iloc[0] = 1.0
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result = df.loc[(0, 0), "z"]
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assert result == 1
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# correct setting
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df.loc[(0, 0), "z"] = 2
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result = df.loc[(0, 0), "z"]
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assert result == 2
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@pytest.mark.slow
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def test_indexer_caching():
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# GH5727
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# make sure that indexers are in the _internal_names_set
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n = 1000001
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arrays = (range(n), range(n))
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index = MultiIndex.from_tuples(zip(*arrays))
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s = Series(np.zeros(n), index=index)
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str(s)
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# setitem
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expected = Series(np.ones(n), index=index)
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s = Series(np.zeros(n), index=index)
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s[s == 0] = 1
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tm.assert_series_equal(s, expected)
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