ggsci

Scientific and sci-fi color palettes from the R package ggsci, packaged as static Rust data.

This crate includes non-Gephi, non-iTerm palettes generated from upstream. PaletteKind::Discrete maps categories to individual colors, while PaletteKind::Continuous maps a continuous domain through an interpolated gradient. These are scale semantics: whether palette data is stored or generated is an orthogonal implementation detail.

The gsea, bs5, material, and tw3 families are continuous. Their arbitrary-length output reproduces ggsci for R's colorRamp(..., space = "Lab", interpolate = "spline"), including its FMM cubic spline, gamut handling, rounding, and endpoint behavior.

Use take() for discrete category colors:

let palette = ggsci::palette("npg", "nrc")?;
let colors = palette.take_hex(3)?;

assert_eq!(colors, ["#E64B35", "#4DBBD5", "#00A087"]);
# Ok::<(), ggsci::Error>(())

Use interpolate() for a continuous gradient, or sample() when accepting either kind:

use ggsci::{palette_by_spec, ContinuousOptions};

let palette = palette_by_spec("material:blue-grey")?;

let colors = palette.interpolate(256)?;
let sampled = palette.sample(256)?;
let reversed = palette.interpolate_with(
    256,
    ContinuousOptions::new().with_reverse(true),
)?;
let translucent = palette.interpolate_rgba(256, 0.6)?;

assert_eq!(colors, sampled);
assert_eq!(colors.len(), 256);
assert_eq!(reversed.len(), 256);
assert_eq!(translucent.len(), 256);
# Ok::<(), ggsci::Error>(())

Palette::colors() returns canonical source colors: category colors for a discrete palette and interpolation anchors for a continuous palette. Its length therefore does not limit how many colors a continuous palette can produce. Reverse is applied after interpolation, matching R. The continuous RGBA methods accept finite alpha values in (0.0, 1.0].

Lookup is case-insensitive and accepts _, -, and spaces interchangeably:

let palette = ggsci::palette_by_spec("material:blue-grey")?;
assert_eq!(palette.family(), "material");
assert_eq!(palette.variant(), "blue-grey");
# Ok::<(), ggsci::Error>(())

The crate has no runtime dependencies, no feature flags, and no build script. R-generated exact-channel fixtures are checked in and run as ordinary Rust integration tests. R is only a maintainer dependency for regenerating palette data and fixtures with cargo xtask update-palettes.