BUG: loc with empty multiindex raises exception #38711
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Added test case for the changes made in GH#36936 |
kasim95
changed the title
| df.loc[df.loc[df.loc[:, "value"] == 0].index, "value"] = 5 | ||
| result = df | ||
| expected = DataFrame([1, 2, 3, 4], index=index, columns=["value"]) | ||
| tm.assert_equal(result, expected) |
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does tm.assert_frame_equal not work here? (and above)
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The assertion method is changed to tm.assert_frame_equal in the most recent commit.
jreback
changed the title
jreback
added
Indexing
| # loc on empty multiindex == loc with False mask | ||
| empty_multiindex = df.loc[df.loc[:, "value"] == 0, :].index | ||
| result = df.loc[empty_multiindex, :] | ||
| expected = df.loc[[False] * len(df.index), :] |
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can you construct the expected frame explicityly
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Constructing an empty DataFrame named expected with Multiindex assigns the expected.index.inferred_type attribute to object by default.
The value of result.index.inferred_type attribute is string as inferred from the index variable created earlier.
This fails the tm.assert_frame_equal test
I used the following code to create an empty dataframe with multiindex:
def test_loc_empty_multiindex():
# GH#36936
arrays = [["a", "a", "b", "a"], ["a", "a", "b", "b"]]
index = MultiIndex.from_arrays(arrays, names=("idx1", "idx2"))
df = DataFrame([1, 2, 3, 4], index=index, columns=["value"])
# loc on empty multiindex == loc with False mask
empty_multiindex = df.loc[df.loc[:, "value"] == 0, :].index
result = df.loc[empty_multiindex, :]
index2 = MultiIndex(levels=[[], []], codes=[[], []], names=["idx1", "idx2"])
expected = DataFrame([], index=index2, columns=["value"], dtype="string")
expected = expected.astype({"value": "int"})
tm.assert_frame_equal(result, expected) # this test fails
# replacing value with loc on empty multiindex
df.loc[df.loc[df.loc[:, "value"] == 0].index, "value"] = 5
result = df
expected = DataFrame([1, 2, 3, 4], index=index, columns=["value"])
tm.assert_frame_equal(result, expected)If the index variable is used directly to create the empty dataframe, it introduces NaN values
| @@ -695,3 +695,22 @@ def test_loc_getitem_index_differently_ordered_slice_none(): | |||
| columns=["a", "b"], | |||
| ) | |||
| tm.assert_frame_equal(result, expected) | |||
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| def test_loc_empty_multiindex(): | |||
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can you co-locate this with similar tests
jreback@lhs2:~/pandas-dev$ grep empty pandas/tests/indexing/multiindex/*
pandas/tests/indexing/multiindex/test_getitem.py:def test_frame_getitem_multicolumn_empty_level():
pandas/tests/indexing/multiindex/test_getitem.py:def test_frame_mi_empty_slice():
pandas/tests/indexing/multiindex/test_loc.py: empty = Series(data=[], dtype=np.float64)
pandas/tests/indexing/multiindex/test_loc.py: result = x.loc[empty]
pandas/tests/indexing/multiindex/test_loc.py: # empty array:
pandas/tests/indexing/multiindex/test_loc.py: empty = np.array([])
pandas/tests/indexing/multiindex/test_loc.py: result = x.loc[empty]
pandas/tests/indexing/multiindex/test_loc.py: ([], []), # empty ok
pandas/tests/indexing/multiindex/test_loc.py:def test_loc_getitem_duplicates_multiindex_empty_indexer(columns_indexer):
pandas/tests/indexing/multiindex/test_loc.py: # empty indexer
IOW there are 2 tests in the test_getitem.py that are testing basically the same, so locate there.
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Moved the test to pandas/tests/indexing/multiindex/test_getitem.py
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thanks @kasim95 |
black pandasgit diff upstream/master -u -- "*.py" | flake8 --diff