Fixes a bug where Series.iloc assignment incorrectly converted dictionary values to Series objects when the target Series had dtype="object". This issue occurred due to improper handling in the Copy-on-Write (CoW) implementation.
#62795
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added 9 commits
October 22, 2025 18:25
…d weakrefs when clearing referenced_blocks; add regression tests
…H#62787 CoW replace np.nan bug
…FINAL_REPORT.md line endings
… stale indices and dead weakrefs (GH#62787)
…avoid breaking external references (GH#62787)
- Tests verify iloc preserves dictionaries in object dtype Series - Covers edge cases: nested dicts, multiple assignments, consistency with direct assignment - Includes regression test for original bug scenario - All tests pass pre-commit checks
- Remove unused numpy and pandas._testing imports - Standardize string quotes to double quotes throughout - Add trailing commas and fix whitespace - Pre-commit formatting improvements
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Please refer to my prior comment #62789 (comment) |
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Background
s.iloc[0] = {}would convert the dictionary to a Series, whiles[0] = {}worked correctlyChanges Made
s[0] = {}) and iloc assignment (s.iloc[0] = {})Tests Added
Added
tests/indexing/test_iloc_dict_assignment.pywith 10 comprehensive test cases:Verification
Related
Series.ilocwithdtype="object"converts dictionary toSeries#62723Type of change