dylaunator

Python port of mapbox/delaunator (v5.0.x API): fast Delaunay triangulation of 2D points using half-edge connectivity.

Upstream pin: logic and tests are aligned with mapbox/delaunator@v5.0.1. See docs/UPSTREAM_TESTS.md for fixture provenance and how tests map to test/test.js.

Robust orientation uses pyrobust-predicates (Python port of mourner/robust-predicates), matching the JavaScript chain (delaunator → robust-predicates) used by d3-delaunay.

Requirements

• Python 3.10+
• Runtime dependency: pyrobust-predicates

Install

uv add dylaunator

Usage

from dylaunator import Delaunator

coords = [377, 479, 453, 434, 326, 387]
d = Delaunator(coords)
print(list(d.triangles))

Flat coordinates may be a Python array("d", ...) or any sequence of floats; use Delaunator.from_points for nested point lists or custom {x, y} objects.

JS API mapping (mapbox/delaunator v5.0.x)

The public npm API is a default-export class; Python exposes the same surface with idiomatic naming where the language requires it.

Also exported (not separate npm exports, but mirror helpers inside upstream index.js): flat_array, flat_iterable, default_get_x, default_get_y.

Constructor validation mirrors upstream where possible (e.g. flat coords must be numeric; array-like objects with negative length raise ValueError with message Invalid typed array length).

Testing and coverage

From the repo root (uv workspace):

uv run pytest packages/dylaunator -q
uv run pytest packages/dylaunator --cov=dylaunator --cov-report=term-missing

The suite includes a full port of upstream test/test.js plus small internal coverage tests. Package source is kept at 100% line coverage under that configuration.

Upstream test fixtures

JSON under tests/fixtures/ matches upstream test/fixtures/*.json at v5.0.1 (byte-for-byte). Details: docs/UPSTREAM_TESTS.md.

Releasing (PyPI)

1. Publish pyrobust-predicates first (runtime dependency of this package).
2. From this directory:

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

Built artifacts land in the workspace dist/ when using uv from a package subfolder. Bump version in pyproject.toml and add a section to docs/CHANGELOG.md before each release.

License

ISC (same as upstream delaunator).