lichtung-plot

lichtung-plot is a strongly typed scientific plotting library for Polars dataframes. It produces one canonical SVG scene, can convert its text to vector paths, and can optionally rasterize that scene to PNG.

This first standalone-boundary release intentionally has no dependency on the Lichtung analysis, pipeline, asset, or reporting crates. Callers supply precomputed inferential annotations as ordinary plotting data.

The renderer is maintained in its own repository. Its architecture and output contracts live in specs/; user guides live in docs/.

use lichtung_plot::Chart;
use polars::df;

let data = df!(
    "x" => [1.0, 2.0, 3.0],
    "y" => [1.5, 2.5, 2.0],
)?;
let mut chart = Chart::new(&data);
chart.x("x").y("y").scatter();
let svg = chart.render_to_svg_bytes()?;
# Ok::<(), Box<dyn std::error::Error>>(())

Fonts

SVG output references this ordered system-font stack and does not download or embed fonts:

Noto Sans, Noto Sans CJK SC, DejaVu Sans, Liberation Sans, Arial, sans-serif

PNG rendering scans system font directories and selects the first installed family from that order. Exact text appearance therefore depends on the host's installed fonts, while chart data, geometry, layout, and SVG structure remain deterministic for the same inputs and environment.

Enable text-as-path and call RenderedSvgScene::svg_with_text_as_paths when the SVG must carry glyph outlines instead of selectable <text> elements. This uses the same local font policy and embeds no font files.

Features

Feature	Default	Capability
text-as-path	No	Convert canonical SVG text to self-contained vector paths
png	No	Enable text outlining and rasterize the canonical SVG scene to PNG

SVG output is always available. PDF output is deliberately outside this crate.

Development

The repository pins its Rust toolchain and tracks Cargo.lock. Run the complete read-only verification before committing:

just verify

Focused recipes include just test, just test-png, just lint, and just lint-png.