ENH: Implement MultiIndex.insert_level for inserting levels at specified positions #62610
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added 2 commits
October 7, 2025 20:43
- Implement insert_level method for MultiIndex to insert new levels at specified positions - Add comprehensive test cases for the new functionality - Fix level names handling to match expected behavior Resolves: MultiIndex level insertion feature request
- Implement insert_level method for MultiIndex to insert new levels at specified positions - Add comprehensive test cases for the new functionality - Fix level names handling to match expected behavior Resolves: MultiIndex level insertion feature request
Chiwendaiyue
changed the title
added 4 commits
October 7, 2025 21:57
- Implement insert_level method for MultiIndex to insert new levels at specified positions - Add comprehensive test cases for the new functionality - Fix level names handling to match expected behavior Resolves: MultiIndex level insertion feature request
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| def setup_method(self): | ||
| self.simple_idx = pd.MultiIndex.from_tuples( | ||
| [("A", 1), ("B", 2), ("C", 3)], names=["level1", "level2"] | ||
| ) | ||
| self.empty_idx = pd.MultiIndex.from_tuples([], names=["level1", "level2"]) |
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NIT: I would prefer that you define this in the test body that should use it.
| ) | ||
| self.empty_idx = pd.MultiIndex.from_tuples([], names=["level1", "level2"]) | ||
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| def test_insert_level_basic(self): |
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Can you parametrize this test?
| result = self.simple_idx.insert_level(0, "new_val", name="new_level") | ||
| assert result.names[0] == "new_level" | ||
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| def test_insert_level_edge_positions(self): |
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This can go into the first test.
| result_end = self.simple_idx.insert_level(2, "end") | ||
| assert result_end.nlevels == 3 | ||
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| def test_insert_level_error_cases(self): |
| with pytest.raises(ValueError, match="Length of values must match"): | ||
| self.simple_idx.insert_level(1, ["too", "few"]) | ||
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| def test_insert_level_with_different_data_types(self): |
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These tests could go into the first test too.
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| def test_debug_names(): | ||
| idx = pd.MultiIndex.from_tuples( | ||
| [("A", 1), ("B", 2), ("C", 3)], names=["level1", "level2"] | ||
| ) | ||
| print("Original names:", idx.names) | ||
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| result = idx.insert_level(0, "new_value") | ||
| print("Result names:", result.names) | ||
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| expected = pd.MultiIndex.from_tuples( | ||
| [("new_value", "A", 1), ("new_value", "B", 2), ("new_value", "C", 3)], | ||
| names=[None, "level1", "level2"], | ||
| ) | ||
| print("Expected names:", expected.names) |
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| tm.assert_index_equal(original, self.simple_idx) | ||
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| assert result.nlevels == original.nlevels + 1 |
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This assertion feels redundant against the first test.
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| def test_insert_level_with_name(self): | ||
| result = self.simple_idx.insert_level(0, "new_val", name="new_level") | ||
| assert result.names[0] == "new_level" |
There was a problem hiding this comment.
You could also test adding names in the first test and remove this test.
Co-authored-by: Álvaro Kothe <[email protected]>
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Adds
insert_levelmethod to MultiIndex for inserting new levels at specified positions.This addresses the feature request in issue #62558 for a simple way to add levels to MultiIndex at given positions.
insert_levelmethod inpandas/core/indexes/multi.pypandas/tests/indexes/multi/test_insert_level.pyidx = pd.MultiIndex.from_tuples([('A', 1), ('B', 2)])
result = idx.insert_level(1, 'new_level')