pyrobust-predicates

Python port of mourner/robust-predicates (v3.0.x): adaptive-precision geometric predicates with the same y-down 2D convention as the JavaScript library.

Upstream pin: tests and fixtures target mourner/robust-predicates@v3.0.3. See docs/UPSTREAM_TESTS.md for how test/test.js maps to pytest.

This package backs dylaunator (mapbox/delaunator in Python) so Delaunay code can run without Node.

Requirements

• Python 3.10+
• Runtime dependency: mpmath (extended-precision fallback for incircle / insphere when the float filter is inconclusive; orient2d / orient3d follow the upstream expansion style in esm/)

Install

uv add pyrobust-predicates

API (matches upstream index.js)

Named exports are the same eight functions as npm:

Returns are numeric (typically float; fast paths may yield int). Compare to zero for the geometric sign; orient2d / orient2dfast are not identical on ill-conditioned input (upstream treats robust vs fast as different entry points).

Testing and coverage

uv run pytest packages/pyrobust-predicates -q
uv run pytest packages/pyrobust-predicates --cov=pyrobust_predicates --cov-report=term-missing

Includes a pytest port of upstream test/test.js (fixtures under tests/fixtures/*.txt), export parity checks, and small _util tests. Package source is kept at 100% line coverage under that configuration.

Upstream test fixtures

.txt files under tests/fixtures/ match upstream test/fixtures/*.txt at v3.0.3. Details: docs/UPSTREAM_TESTS.md.

Releasing (PyPI)

From this directory:

uv build
uv publish  # or upload dist/* with twine

Artifacts are written to the workspace dist/. Bump version in pyproject.toml and record changes in docs/CHANGELOG.md before each release. Publish this package before dylaunator, which depends on it.

License

Unlicense (public domain), matching upstream robust-predicates.