figure-gate

figure-gate reads a matplotlib figure you have already built and tells you which publication requirements it fails. It checks colorblind-safe color, composition, and whether your type is still legible at the size the figure prints.

report(fig) prints one line per check:

Composition audit
  [FAIL] Clipping           clipped: ['x', 'y']  [FIX] add constrained_layout or widen the figure
  [PASS] Type size          smallest 10.0pt on page (floor 7.5)
  [WARN] Alt text           no description attached  [FIX] describe(fig, "...") ...
  ...
  -> FIX THE MARKED CHECKS

Thirteen rows can fail a build. The other eight are advisory: they report WARN and never FAIL. For a program rather than a person, audit(fig) returns (ok, rows), 21 rows, one per check, each a (name, status, detail) triple, and audit_json(fig) serialises the same verdict.

figure-gate verifies figures. It does not draw them, restyle them, or judge whether a figure is good. Each check forbids one named defect, so a figure that passes every row has avoided 21 named defects and nothing more.

Every threshold is a module-level constant you can read, change, or set from a figure-gate.toml.

Try it

pip install figure-gate                  # or: uv add figure-gate
check-palette "#E69F00,#56B4E9,#009E73" --pairs all
check-figure                             # self-test on a deliberately broken figure

check-figure prints a failing report and exits 0: its self-test passes only when the checker rejects the broken figure.

Copying the scripts in works too, and is the route if you want the thresholds beside the figures they gate. The install page covers all three routes.

python examples/demo.py builds that figure and audits it. python examples/gallery.py builds the harder forms. Writing those twenty exposed defects in the checks themselves, listed on the gallery page.

Documentation

The documentation site is organised by what you came to do.

Learning

Start here if you have not run the checkers before:

Doing a task

Step-by-step directions for a goal you already have:

Looking something up

What each check measures and what each function takes:

Understanding why

Background, evidence, and the decisions behind the thresholds:

Use it with Claude Code

This repository is also a plugin marketplace, so Claude Code applies the same checks when it builds a figure for you. See Install it as a Claude Code skill.

Where this sits

Prescriptive style sheets already exist and are good: SciencePlots and LovelyPlots for journal looks, tueplots and mpl_sizes for exact conference sizing. Accessibility tooling exists too: matplotalt generates alt text, Chart4Blind converts a chart image into an accessible one, and contrast reporters check colors in isolation.

Each of those acts before or beside the figure. None of them reads the built result and reports what it fails. A style sheet and figure-gate are complementary: set your defaults with one, verify them with the other.

Stability

Below version 1.0, a minor release may break the public API, and every break is named in the changelog. The version policy says what the public API covers.

Contributing

New gates are welcome at the bar the project holds itself to:

• A test proving the gate fails on a figure with that defect.
• A test proving it does not over-fire on the nearest legitimate case.
• A note naming the real failure that motivated it.

See CONTRIBUTING.md and SECURITY.md.

License

MIT. See LICENSE.