malevich

Terminal plotting for Rust: a small grammar of marks, honest axes, millions of points.

Eight marks. A real statistics layer. Ten million points in 28 milliseconds. Axes placed by the same algorithm the visualization literature settled on — with labels that are exact decimals, never 0.30000000000000004. All of it in plain values that render to a String, degrade gracefully on any terminal, and never touch global state.

println!("{}", malevich::line(&[1.0, 5.0, 2.0, 8.0][..]));

8 ┤                         ⡠⠊
  │                       ⡠⠊
  │       ⣀⠤⠒⠤⣀        ⢀⠔⠉
4 ┤    ⡠⠔⠊     ⠉⠒⠤⣀  ⢀⠔⠁
  │⢀⡠⠔⠉            ⠉⠒⠁
0 ┤⠁
  └┬────────┬───────┬────────┬
   0        1       2        3

println!("{}", malevich::bar(["mon", "tue", "wed", "thu", "fri"], &[3.0, 7.0, 4.5, 8.0, 6.0][..]));

8 ┤         ▁▁▁▁▁         █████
  │         █████         █████  ▃▃▃▃▃
  │         █████         █████  █████
4 ┤         █████  █████  █████  █████
  │  ▆▆▆▆▆  █████  █████  █████  █████
  │  █████  █████  █████  █████  █████
0 ┤  █████  █████  █████  █████  █████
  └─────────────────────────────────────
      mon    tue    wed    thu    fri

And the charts no other terminal library ships — box plots, violins, densities, 2D histograms:

                 flipper length by species
  230 ┤                                        ⠉⠉⢹⠉⠉
      │                                          ⢸
  220 ┤                                       ⣿⣿⣿⣿⣿⣿⣿⡇
      │                                       ━━━━━━━━
  210 ┤        ⣀⣀⣄⣀⣀           ⠉⠉⢹⠉⠉          ⠉⠉⠉⢹⠉⠉⠉⠁
m     │          ⡇               ⢸             ⣀⣀⣸⣀⣀
m 200 ┤          ⡇           ⢰⣶⣶⣶⣾⣶⣶⣶⡆
      │      ⢠⣤⣤⣤⣧⣤⣤⣤        ⢸━━━━━━━━
  190 ┤      ⢸⣿⣿⣿⣿⣿⣿⣿        ⠘⠛⠛⠛⢻⠛⠛⠛⠃
      │      ━━━━━━━━━           ⢸
  180 ┤          ⡇               ⢸
      │          ⡇             ⠉⠉⠉⠉⠉
  170 ┤        ⠉⠉⠋⠉⠉
      └─────────────────────────────────────────────────────
              Adelie         Chinstrap        Gentoo

And the classic asciichart look, one glyph per column, whenever you want charts this quiet — with real axes underneath, which the original never had:

Plot::new().layer(Line::y(&values[..]).style(LineStyle::Corners))

                          the corners style
 15 ┤              ╭───────────╮
    │            ╭─╯           ╰─╮
 10 ┤          ╭─╯               ╰──╮
    │        ╭─╯                    ╰╮
  5 ┤      ╭─╯                       ╰─╮
    │     ╭╯                           ╰─╮
  0 ┤     ╯                              ╰╮
    │                                     ╰─╮
 -5 ┤                                       ╰─╮
    │                                         ╰╮                   ╭──
-10 ┤                                          ╰──╮              ╭─╯
    │                                             ╰─╮         ╭──╯
-15 ┤                                               ╰─────────╯
    └┬──────────┬─────────┬──────────┬──────────┬──────────┬─────────┬
     0         10        20         30         40         50        60

Every chart in these docs is real program output, spliced in by cargo run --example regen_docs and verified in CI — never typed by hand. More in the gallery: EXAMPLES.md, and cargo run --example showcase renders a colored tour sized to your terminal.

Why malevich

A small grammar, not a chart zoo. Eight marks (line, points, bars, area, cells, range, rule, text) × a stats layer × shared scales compose into the whole basic chart catalog. Every preset — line, scatter, bar, hist, stairs, ecdf, heatmap, hist2d, density, box_plot, violin, error_bars — is proven bit-identical to its grammar expansion in tests.
The statistical set no terminal library has. Box plots with type-7 quartiles and Tukey whiskers, violins from a real KDE (Silverman bandwidth), ECDFs, error bars, 2D densities — the charts science and ML actually need.
Millions of points, measured. Large line layers are aggregated by M4 — min/max/first/last per raster column, provably pixel-identical to drawing every point. Ten million points render end to end in ~28 ms single-threaded; a million KDE samples take 23 ms (cargo bench --bench render). Every aggregator is a mergeable monoid, so host-side parallelism and streaming are compositions, not features.
Axes that are actually good. Extended-Wilkinson tick placement (Talbot, Lin, Hanrahan 2010), exact-decimal labels that parse back to their values, one shared SI prefix per axis (2.5M, 100µ), log axes with superscript decades, calendar time axes with multi-scale labels (14:05, Aug 2, 2027), typed axis specs (Scale::{Linear, Log, Time, Bands}), axis titles, band scales with fitted category labels, collision-aware layout that sheds furniture instead of failing.
Renders everywhere, honestly. Six charsets — Unicode 16 octants (braille density, solid ink — auto-selected on terminals known to render them), braille, sextants, quadrants, half-blocks, ASCII — and four color tiers (truecolor → 256 → 16 → plain) with honest downhill quantization; piped output is automatically clean plain text; CJK labels stay aligned; NaN is always a visible gap, never interpolated away.
Small multiples and fixed axes. Grid pastes plots side by side (escape-aware alignment); x_domain/y_domain fix axes matplotlib-style — so shared scales across a dashboard are an explicit composition, not a mode.
A ratatui widget, if you want one. With the ratatui feature (depending only on ratatui-core), plot.widget() drops any chart into a TUI — cells written straight into the buffer, colors as styles, your app keeps the terminal (cargo run --example tui --features ratatui).
Live charts without a framework. A thread-shared sliding window plus an in-place repaint handle (cursor up, erase down, one write): flicker-free streaming that survives in scrollback and never takes over your terminal (cargo run --example live).
Plots are plain values. Clone + Send + Sync, no globals, rendering is a pure function of plot and frame — build on one thread, render on another, snapshot-test the strings. Two tiny dependencies (terminal_size, unicode-width).

Pre-1.0: APIs break between releases while we make them right. The concept vocabulary is documented in TERMINOLOGY.md and changes are in the CHANGELOG.

What it will not be

Not a TUI framework (it never owns the terminal or handles input). No animations. No file parsing or dataframes in core — ingestion traits only. No config-object kitchen sink: if an option is not a mark channel, stat parameter, scale option, or theme entry, it does not ship.

Name

Kazimir Malevich painted a black square on a plain ground and meant it: a small vocabulary of geometric forms, composed deliberately. That is the design budget of this library.

Acknowledgements

malevich stands on the shoulders of giants — the algorithms, libraries, and grammars that taught this project what it knows are credited, specifically, in ACKNOWLEDGEMENTS.md.

License