pyd3js-ease

Python port of d3-ease.

Tracked version: upstream_lock.json (d3-ease@3.0.1).

What is d3-ease?

d3-ease supplies easing functions: maps (t \in [0,1]) for animations and transitions (polynomial, sinusoidal, exponential, elastic, bounce, etc.). This package mirrors the default export surface of the pinned upstream version for use from Python.

What you get

• 100% upstream export parity for the pinned d3-ease@3.0.1 (compatibility matrix and docs/UPSTREAM_API.md).
• 100% line coverage for pyd3js_ease (enforced via --cov-fail-under=100 in this package’s pytest config).
• Pytest ports of every upstream Mocha file for v3.0.1, plus runnable docs (README + docs/USER_GUIDE.md) checked like pyd3js-array.
• D3-style ease* names and aliases; polynomial, back, and elastic configurators expose .exponent, .overshoot, .amplitude / .period like upstream (as callable classes in Python).

Install

From PyPI:

pip install pyd3js-ease

The published package has no third-party Python dependencies (standard library only).

Workspace development:

uv sync --group dev

Usage

import pyd3js_ease as d3

print(d3.easeCubicIn(0.5))
print(d3.easeQuad is d3.easeQuadInOut)

p = d3.easePolyIn.exponent(2.5)
print(round(p(0.5), 6))

f = d3.easeElasticIn.amplitude(1.3).period(0.2)
print(round(f(0.5), 6))

0.125
True
0.176777
-0.030303

Compatibility matrix

Pinned upstream inventory: docs/UPSTREAM_API.md.

Legend:

• [implemented]: ported for the pinned version; covered by Python tests.
• [missing]: reserved for upstream drift (should not appear for the pinned version).

Upstream exports (d3-ease@3.0.1)

• easeLinear — [implemented]
• easeQuad — [implemented]
• easeQuadIn — [implemented]
• easeQuadOut — [implemented]
• easeQuadInOut — [implemented]
• easeCubic — [implemented]
• easeCubicIn — [implemented]
• easeCubicOut — [implemented]
• easeCubicInOut — [implemented]
• easePoly — [implemented]
• easePolyIn — [implemented]
• easePolyOut — [implemented]
• easePolyInOut — [implemented]
• easeSin — [implemented]
• easeSinIn — [implemented]
• easeSinOut — [implemented]
• easeSinInOut — [implemented]
• easeExp — [implemented]
• easeExpIn — [implemented]
• easeExpOut — [implemented]
• easeExpInOut — [implemented]
• easeCircle — [implemented]
• easeCircleIn — [implemented]
• easeCircleOut — [implemented]
• easeCircleInOut — [implemented]
• easeBounce — [implemented]
• easeBounceIn — [implemented]
• easeBounceOut — [implemented]
• easeBounceInOut — [implemented]
• easeBack — [implemented]
• easeBackIn — [implemented]
• easeBackOut — [implemented]
• easeBackInOut — [implemented]
• easeElastic — [implemented]
• easeElasticIn — [implemented]
• easeElasticOut — [implemented]
• easeElasticInOut — [implemented]

Python-only exports

The module also documents PolyIn, PolyOut, PolyInOut, BackIn, BackOut, BackInOut, ElasticIn, ElasticOut, ElasticInOut, and __version__ for typing and explicit construction (not separate names in upstream index.js).

Testing

From repo root:

uv run pytest packages/pyd3js-ease/package_tests -q --cov=pyd3js_ease --cov-report=term-missing --cov-fail-under=100

uv run ruff format packages/pyd3js-ease
uv run ruff check packages/pyd3js-ease
uv run ty check packages/pyd3js-ease/src

Documentation

• User guide: docs/USER_GUIDE.md
• Changelog: docs/CHANGELOG.md
• Roadmap: docs/ROADMAP.md
• Upstream update checklist: docs/UPSTREAM_UPDATE.md