Round half-way values towards positive infinity in ROUND - #81
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SPARQL 1.1 17.4.4.2 (fn:numeric-round): of two equally close integers, the one closest to positive infinity is returned, so round(-2.5) = -2. Polars only offers half-away-from-zero, so negative ties are moved one step up. Refs DataTreehouse#78. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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Requested by Mathias
Fixes #78.
Before:
ROUNDrounded negative half-way values away from zero, soROUND(-2.5)returned -3 andROUND(-0.5)returned -1.After: ties go towards positive infinity, as SPARQL 1.1 §17.4.4.2 requires:
ROUND(-2.5)= -2,ROUND(-0.5)= 0,ROUND(2.5)= 3. Non-tie values and integers are unchanged.How: Polars only offers
HalfToEvenandHalfAwayFromZero. The newsparql_roundhelper rounds half away from zero, then moves negative ties one step up. A value is a negative tie exactly whenx - round(x) == 0.5; that subtraction is exact for ties, also for floats. Integer types are passed through. The helper is used for both single-typed and multi-typed columns. I also removed an unconditionalwith_column(round(...))at the top ofround_, which every branch below overwrote anyway.Tests:
py_maplib/tests/test_round.py(13 cases: decimal, double and integer literals, plus values read from a graph).🤖 Generated with Claude Code