ggplot-rs 0.16.0

A Rust implementation of ggplot2's Grammar of Graphics
Documentation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
# ggplot-rs

[![CI](https://github.com/sipemu/ggplot-rs/actions/workflows/ci.yml/badge.svg)](https://github.com/sipemu/ggplot-rs/actions/workflows/ci.yml)
[![Crates.io](https://img.shields.io/crates/v/ggplot-rs.svg)](https://crates.io/crates/ggplot-rs)
[![Documentation](https://docs.rs/ggplot-rs/badge.svg)](https://docs.rs/ggplot-rs)
[![codecov](https://codecov.io/gh/sipemu/ggplot-rs/branch/main/graph/badge.svg)](https://codecov.io/gh/sipemu/ggplot-rs)
[![License: MIT OR Apache-2.0](https://img.shields.io/badge/license-MIT%2FApache--2.0-blue.svg)](#license)

A Rust implementation of ggplot2's Grammar of Graphics, rendering through a
self-contained SVG backend (no dependencies) or, with the default `plotters`
feature, the [plotters](https://github.com/plotters-rs/plotters) SVG/bitmap backend.

**Validated against R.** Computed layers — binning, density, stacking, QQ/ECDF,
LOESS, and axis-tick placement (extended-Wilkinson) — are checked against
[R ggplot2](https://ggplot2.tidyverse.org/) 4.0.3's `ggplot_build()` output, so a
histogram or a stacked bar comes out where ggplot2 puts it. See
[`validation/`](validation/).

**No polars required.** [polars](https://pola.rs/) is a convenient — and fully
optional — input adapter. The core pipeline runs on its own internal DataFrame,
so you can plot straight from plain Rust vectors, or from
[Apache Arrow](https://arrow.apache.org/) `RecordBatch`es produced by
[DuckDB](https://duckdb.org/) — with polars switched off entirely. See
[Data Input](#data-input) and [Feature Flags](#feature-flags).

## Gallery

Every image below is produced by [`examples/gallery.rs`](examples/gallery.rs) —
regenerate them all with `cargo run --features sf --example gallery` (the
choropleth needs the `sf` feature; drop it for the rest).

<table>
  <tr>
    <td align="center" width="33%">
      <img src="assets/gallery/scatter.png" width="260" alt="Grouped scatter"><br>
      <sub>Grouped scatter · <code>geom_point</code></sub>
    </td>
    <td align="center" width="33%">
      <img src="assets/gallery/smooth.png" width="260" alt="LOESS smoothing"><br>
      <sub>LOESS trend + CI · <code>geom_smooth</code></sub>
    </td>
    <td align="center" width="33%">
      <img src="assets/gallery/continuous_color.png" width="260" alt="Continuous color"><br>
      <sub>Continuous color · viridis</sub>
    </td>
  </tr>
  <tr>
    <td align="center">
      <img src="assets/gallery/histogram.png" width="260" alt="Histogram"><br>
      <sub>Histogram · <code>geom_histogram</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/density.png" width="260" alt="Density by group"><br>
      <sub>Densities · <code>geom_density</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/bar.png" width="260" alt="Bar chart"><br>
      <sub>Bar chart · <code>geom_bar</code></sub>
    </td>
  </tr>
  <tr>
    <td align="center">
      <img src="assets/gallery/boxplot.png" width="260" alt="Boxplot"><br>
      <sub>Boxplots · <code>geom_boxplot</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/violin.png" width="260" alt="Violin"><br>
      <sub>Violins · <code>geom_violin</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/jitter.png" width="260" alt="Jitter"><br>
      <sub>Jittered points · <code>geom_jitter</code></sub>
    </td>
  </tr>
  <tr>
    <td align="center">
      <img src="assets/gallery/contour_filled.png" width="260" alt="Filled contours"><br>
      <sub>Filled contours · <code>geom_contour_filled</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/hexbin.png" width="260" alt="Hex binning"><br>
      <sub>Hex binning · <code>geom_hex</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/heatmap.png" width="260" alt="Heatmap"><br>
      <sub>Heatmap · <code>geom_tile</code></sub>
    </td>
  </tr>
  <tr>
    <td align="center">
      <img src="assets/gallery/ribbon.png" width="260" alt="Ribbon"><br>
      <sub>Confidence band · <code>geom_ribbon</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/area.png" width="260" alt="Stacked area"><br>
      <sub>Stacked area · <code>geom_area</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/facet.png" width="260" alt="Facet wrap"><br>
      <sub>Small multiples · <code>facet_wrap</code></sub>
    </td>
  </tr>
  <tr>
    <td align="center">
      <img src="assets/gallery/polar.png" width="260" alt="Polar rose chart"><br>
      <sub>Rose chart · <code>coord_polar</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/ecdf.png" width="260" alt="Empirical CDF"><br>
      <sub>Empirical CDF · <code>stat_ecdf</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/qq.png" width="260" alt="Q-Q plot"><br>
      <sub>Q-Q plot · <code>geom_qq</code></sub>
    </td>
  </tr>
  <tr>
    <td align="center">
      <img src="assets/gallery/spatial.png" width="260" alt="Choropleth"><br>
      <sub>Choropleth · <code>geom_sf</code> <sub>(feature <code>sf</code>)</sub></sub>
    </td>
    <td align="center"></td>
    <td align="center"></td>
  </tr>
</table>

### Publication-ready (ggpubr-style)

Journal palettes, `theme_pubr()`, GAM smoothing, and statistical annotations —
the last two need the `regression` / `ggpubr` features. Regenerate with
`cargo run --no-default-features --features regression,ggpubr,plotters --example ggpubr_gallery`.

<table>
  <tr>
    <td align="center" width="33%">
      <img src="assets/gallery/palettes_ggsci.png" width="260" alt="ggsci palette"><br>
      <sub>Journal palettes · <code>scale_color_brewer(Npg)</code></sub>
    </td>
    <td align="center" width="33%">
      <img src="assets/gallery/theme_pubr.png" width="260" alt="theme_pubr"><br>
      <sub>Publication theme · <code>theme_pubr</code></sub>
    </td>
    <td align="center" width="33%">
      <img src="assets/gallery/smooth_gam.png" width="260" alt="GAM smoothing"><br>
      <sub>GAM smoother · <code>geom_smooth</code> gam <sub>(feature <code>regression</code>)</sub></sub>
    </td>
  </tr>
  <tr>
    <td align="center">
      <img src="assets/gallery/stat_cor.png" width="260" alt="stat_cor"><br>
      <sub>Correlation label · <code>stat_cor</code> <sub>(feature <code>ggpubr</code>)</sub></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/compare_means.png" width="260" alt="stat_compare_means"><br>
      <sub>Group p-value · <code>stat_compare_means</code> <sub>(feature <code>ggpubr</code>)</sub></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/brackets.png" width="260" alt="pairwise brackets"><br>
      <sub>Pairwise brackets · <code>stat_compare_means(comparisons)</code> / <code>geom_bracket</code></sub>
    </td>
  </tr>
  <tr>
    <td align="center" colspan="3">
      <img src="assets/gallery/arrange.png" width="540" alt="ggarrange"><br>
      <sub>Multi-plot composition · <code>ggarrange</code> + one-call constructors (<code>ggscatter</code>/<code>ggboxplot</code>/<code>ggdensity</code>)</sub>
    </td>
  </tr>
</table>

### Themes

The same plot under each built-in theme — swap with a single `.theme(theme_*())` call.

<table>
  <tr>
    <td align="center" width="33%">
      <img src="assets/gallery/theme_gray.png" width="240" alt="theme_gray"><br>
      <sub><code>theme_gray</code> (default)</sub>
    </td>
    <td align="center" width="33%">
      <img src="assets/gallery/theme_bw.png" width="240" alt="theme_bw"><br>
      <sub><code>theme_bw</code></sub>
    </td>
    <td align="center" width="33%">
      <img src="assets/gallery/theme_minimal.png" width="240" alt="theme_minimal"><br>
      <sub><code>theme_minimal</code></sub>
    </td>
  </tr>
  <tr>
    <td align="center">
      <img src="assets/gallery/theme_classic.png" width="240" alt="theme_classic"><br>
      <sub><code>theme_classic</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/theme_light.png" width="240" alt="theme_light"><br>
      <sub><code>theme_light</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/theme_dark.png" width="240" alt="theme_dark"><br>
      <sub><code>theme_dark</code></sub>
    </td>
  </tr>
  <tr>
    <td align="center">
      <img src="assets/gallery/theme_linedraw.png" width="240" alt="theme_linedraw"><br>
      <sub><code>theme_linedraw</code></sub>
    </td>
    <td align="center">
      <img src="assets/gallery/theme_void.png" width="240" alt="theme_void"><br>
      <sub><code>theme_void</code></sub>
    </td>
    <td align="center"></td>
  </tr>
</table>

## Quick Start

```rust
use ggplot_rs::prelude::*;
use polars::prelude::*;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let df = df! {
        "sepal_length" => [5.1, 4.9, 4.7, 7.0, 6.4],
        "sepal_width"  => [3.5, 3.0, 3.2, 3.2, 3.2],
        "species"      => ["setosa", "setosa", "setosa", "versicolor", "versicolor"],
    }?;

    GGPlot::new(df)
        .aes(Aes::new().x("sepal_length").y("sepal_width").color("species"))
        .geom_point()
        .save("scatter.svg")?;

    Ok(())
}
```

## Features

### Geoms

`geom_point`, `geom_line`, `geom_bar`, `geom_col`, `geom_histogram`, `geom_boxplot`, `geom_violin`, `geom_smooth`, `geom_density`, `geom_area`, `geom_ribbon`, `geom_errorbar`, `geom_segment`, `geom_rug`, `geom_text`, `geom_label`, `geom_tile`, `geom_raster`, `geom_bin2d`, `geom_hex`, `geom_contour`, `geom_contour_filled`, `geom_path`, `geom_step`, `geom_hline`, `geom_vline`, `geom_abline`, and more (40+)

### Stats

`StatIdentity`, `StatCount`, `StatBin`, `StatBoxplot`, `StatSmooth` (Lm + Loess), `StatDensity`, `StatLoess`, `StatSummary`, `StatEcdf`, `StatFunction`, `StatEllipse`, `StatContour`, `StatBin2d`, `StatBinHex`, `StatSum`, `StatYDensity`, `StatQQ`, `StatSummary2d`, `StatQuantile` (feature `regression`), and more

### Scales

- **Continuous**: linear, log10, log2, ln, sqrt, reverse, logit, probit, pseudo-log, reciprocal, exp, and Box–Cox transforms
- **Discrete**: automatic categorical mapping
- **Color**: discrete palettes (Viridis, Brewer Set1/Dark2, etc.), continuous gradients, diverging gradient2, binned/stepped scales (`scale_color_steps`/`fermenter`), manual color assignment
- **Shape & Linetype**: discrete mapping for point shapes and line styles

### Coordinates

`coord_cartesian`, `coord_flip`, `coord_fixed`, `coord_polar`, `coord_trans`

### Spatial (`geom_sf`)

Behind the optional `sf` feature, `geom_sf` renders simple-features geometry —
points, lines, and (multi)polygons with holes — from a `geometry` column of
**WKT** strings. It uses a self-contained WKT parser, so the spatial layer pulls
in **no** extra dependencies. The `fill` aesthetic drives a choropleth, and
axes/legends/facets come from the rest of the grammar as usual:

```rust
let df = df! {
    "geometry"   => ["POLYGON ((0 0, 3 0, 3 2, 0 2, 0 0))", "POLYGON ((3 0, 6 0, 6 3, 3 2, 3 0))"],
    "population" => [4.2, 9.5],
}?;
GGPlot::new(df)
    .aes(Aes::new().fill("population"))
    .geom_sf()
    .scale_fill_viridis_c();
```

**Projections & aspect.** Pass a projection to `geom_sf` and pair it with
`coord_sf()` (equal-aspect, derived from the data extent) for a shape-correct
map — e.g. a conformal Web Mercator:

```rust
use ggplot_rs::spatial::SfProjection;
use ggplot_rs::geom::sf::GeomSf;

GGPlot::new(df)                        // lon/lat WKT in `geometry`
    .aes(Aes::new().fill("value"))
    .geom_sf_with(GeomSf::default().project(SfProjection::Mercator))
    .coord_sf();
```

**Load GeoJSON.** The `geojson` feature reads a `FeatureCollection` into a
plot-ready frame — geometry → WKT, properties → columns:

```rust
use ggplot_rs::spatial::geojson::read_geojson_file;

let cols = read_geojson_file("countries.geojson")?;   // Vec<(String, Vec<Value>)>
GGPlot::new(cols).aes(Aes::new().fill("gdp")).geom_sf();
```

See [`examples/spatial.rs`](examples/spatial.rs) (`cargo run --features sf --example spatial`).

### Faceting

`facet_wrap` and `facet_grid` with free/fixed scales, proportional panel sizing
(`space = "free"` via `facet_grid_space`), and multi-variable columns
(`facet_grid_multi`, R's `rows ~ b + c`). Computed stats (density/histogram) are
estimated per panel.

### Themes

`theme_gray`, `theme_bw`, `theme_classic`, `theme_minimal`, `theme_dark`, `theme_light`, `theme_linedraw`, `theme_void` — plus full customization via `ElementText`, `ElementLine`, `ElementRect`

### Annotations

`annotate_text`, `annotate_rect`, `annotate_segment`

### Guides & axes

- **Legend inside the panel** at panel-relative coords: `legend_position_inside(x, y)` (R's `legend.position = c(x, y)`).
- **Axis label rotation**: `axis_text_x_angle(deg)` / `axis_text_y_angle(deg)` (R's `guide_axis(angle = ...)`).
- **Label dodging**: `axis_text_x_dodge(n)` staggers crowded x labels across `n` rows (`guide_axis(n.dodge)`).
- **Corner tag**: `tag("A")` for figure-panel labels (`labs(tag)`).
- **Axis position & expansion**: `ScaleContinuous::with_position_opposite()` (x-axis on top / y on the right) and `with_expand_sides(...)` for per-side expansion.

Call theme-related builders after any `theme_*()` preset.

### Computed aesthetics

An aesthetic can map an **expression** over columns, not just a bare column name:

```rust
GGPlot::new(data)
    .aes(Aes::new().x("log10(gdp)").y("pop / 1e6").color("deaths / cases"))
    .geom_point();
```

Supports `+ - * / % ^`, parentheses, and `ln`/`log`/`log10`/`log2`/`sqrt`/`exp`/`abs`/`sin`/`cos`/`tan`/`floor`/`ceil`/`round`/`sign`. A plain column name is used directly (so existing mappings are unchanged); anything else is parsed and evaluated per row. `after_scale_fill_from_color(l)` / `after_scale_color_from_fill(l)` derive one color aesthetic from another's mapped color, lightness-adjusted (`after_scale`); `Aes::stage(aes, start, after_stat)` maps an aesthetic at two pipeline stages. The same expressions work in `after_stat` mappings, plus aggregate functions (`sum`, `mean`, `max`, `min`, `count`, `median`, `prod`) that reduce over all rows — e.g. `.after_stat_y("count / sum(count)")` for proportion histograms.

## Command-line tool

A `ggplot-rs` CLI (behind the `cli` feature) plots **parquet**/**CSV** files or
**DuckDB SQL** straight from the shell — DuckDB is the query engine:

```sh
cargo install ggplot-rs --features cli

# discover columns first, then plot
ggplot-rs --parquet sales.parquet --describe
ggplot-rs --parquet sales.parquet --x month --y revenue --geom line -o rev.png

# aggregate with SQL (reads parquet globs), faceted bars
ggplot-rs --sql "SELECT region, sum(qty) q FROM 'orders/*.parquet' GROUP BY 1" \
  --x region --y q --geom col --facet-wrap region --theme minimal -o orders.svg
```

Flags: `--x/--y/--color/--fill/--size/--shape/--group`, `--geom`, `--facet-wrap/--facet-grid`,
`--log-x/--log-y/--flip`, `--title/--subtitle/--xlab/--ylab/--caption`, `-o FILE`/`--stdout`,
`--width/--height`. Run `--describe` to list a source's columns and types.

**Maps from the CLI (`--spatial`, `--geom sf`).** DuckDB's
[`spatial`](https://duckdb.org/docs/extensions/spatial) extension reads
**shapefiles**, GeoJSON, GeoPackage, FlatGeobuf and more (via GDAL). Pass
`--spatial` to load it, then `ST_AsText(geom)` any geometry into a `geometry`
column and plot it with `--geom sf`:

```sh
ggplot-rs --spatial \
  --sql "SELECT ST_AsText(geom) AS geometry, name, pop_est
         FROM ST_Read('ne_110m_admin_0_countries.shp')" \
  --geom sf --fill pop_est --projection mercator --theme void -o world.png
```

`ST_Read` handles the file format; `ST_AsText` produces WKT that `geom_sf`
consumes; `--projection mercator` and an equal-aspect `coord_sf` are applied
automatically. Any SQL works, so you can join, filter, or aggregate spatial and
tabular data in the same query before plotting.

**Theming from the CLI:** `--theme <preset>` (gray/bw/minimal/…), `--palette <name>`
(Set1/Dark2/viridis/RdBu/…), `--primary "r,g,b"` (brand color), and `--theme-config <file>`
— a TOML/JSON file of element overrides for full custom theming:

```sh
ggplot-rs --parquet d.parquet --x a --y b --color g --palette Dark2 --primary "26,153,136" -o p.png
ggplot-rs --parquet d.parquet --x a --y b --color g --theme-config brand.toml -o p.png
```

```toml
# brand.toml — applied on top of the base preset
base = "minimal"
palette = "RdBu"
primary = [200, 60, 40]
[title]
size = 22
color = [40, 40, 90]
[panel_background]
fill = [248, 246, 240]
[panel_grid_major]
linetype = "dashed"
[legend]
position = "inside"
x = 0.9
y = 0.9
```

**AI-ready:** the repo ships a Claude Code skill at `.claude/skills/plot-data/` that
teaches an agent the describe-then-map-then-render workflow, so "plot this parquet"
just works.

## In the browser (WASM)

**▶ Live demo: <https://sipemu.github.io/ggplot-rs/>** — DuckDB-Wasm reads Natural
Earth countries into a hover-able choropleth, plus a **100k-point scatter** via the
raster backend.

The [`crates/ggplot-rs-wasm`](crates/ggplot-rs-wasm) workspace crate (a `cdylib`,
not published) exposes a plotters-free renderer to JavaScript via `wasm-bindgen`.
It compiles to `wasm32` and uses the self-contained [`SvgBackend`](#rendering), so
the bundle is small (~310 KB `.wasm`, no polars, no fonts — text is `<text>` the
browser draws). The `ggplot-rs` library itself is a plain `rlib` with no
wasm-specific dependencies, so it also builds for `wasm32-unknown-unknown` /
emscripten targets directly (`default-features = false`):

```sh
wasm-pack build crates/ggplot-rs-wasm --target web --out-dir ../../web/pkg --out-name ggplot_rs
```

```js
import init, { render_geo } from "./pkg/ggplot_rs.js";
await init();
document.getElementById("plot").innerHTML = render_geo(JSON.stringify({
  geometry: [...wkt], fill: [...nums], label: [...names], projection: "mercator",
}));
```

Every mark is a real DOM element, so **hover works out of the box** — each feature
carries a `<title>` tooltip (from a `label` mapping + the fill value), plus CSS
`:hover` for highlight.

Pair it with **[DuckDB-Wasm](https://github.com/duckdb/duckdb-wasm)** (which loads
the same `spatial` extension) to read shapefiles/GeoJSON and `ST_AsText` them to
WKT entirely client-side.

**Large N.** SVG is one DOM node per mark (great to ~10k–50k). For more, the
`canvas` feature adds a self-contained **RGBA raster backend** (`render_rgba` /
`render_png_raster`, or the wasm crate's `render_scatter_rgba`) — it rasterises everything in
pure Rust (text via `ab_glyph`), so it's fast and wasm-compatible: 500k points
render in a fraction of a second to a bitmap you blit with `putImageData`. (Or
aggregate in DuckDB — `GROUP BY`, hex-bins, sampling — and render the summary.)
See [`web/`](web/) for a runnable demo that fetches Natural Earth countries:

<p align="center"><img src="assets/gallery/world.png" width="640" alt="World population choropleth from Natural Earth via DuckDB spatial"></p>

The same render is one CLI command (native, identical `render_svg_native` path):

```sh
ggplot-rs --spatial \
  --sql "SELECT ST_AsText(geom) AS geometry, NAME AS label, ln(POP_EST+1) AS pop
         FROM ST_Read('ne_110m_admin_0_countries.geojson') WHERE NAME <> 'Antarctica'" \
  --geom sf --fill pop --label label --theme void -o world.png
```

## Data Input

`GGPlot::new` accepts anything implementing the `GGData` trait. Nothing here
requires polars — pick whichever source fits your stack.

**Plain Rust — zero optional dependencies:**

```rust
// Column-oriented
let cols: Vec<(String, Vec<Value>)> = vec![
    ("x".into(), vec![Value::Float(1.0), Value::Float(2.0), Value::Float(3.0)]),
    ("y".into(), vec![Value::Float(4.0), Value::Float(5.0), Value::Float(6.0)]),
];
GGPlot::new(cols)

// Row-oriented
let rows: Vec<HashMap<String, Value>> = vec![/* ... */];
GGPlot::new(rows)
```

**Apache Arrow / DuckDB** — feed a `RecordBatch` straight from a DuckDB query
result, with polars switched off:

```toml
# Cargo.toml — no polars in the dependency tree (add "plotters" for render_svg/render_png)
ggplot-rs = { version = "0.16", default-features = false, features = ["arrow"] }
```

```rust
let batch: arrow::record_batch::RecordBatch = /* DuckDB query → Arrow */;
GGPlot::new(batch)
```

**polars** (optional, enabled by default) — for `df!` and polars pipelines:

```rust
let df = df! {
    "x" => [1.0, 2.0, 3.0],
    "y" => [4.0, 5.0, 6.0],
}?;
GGPlot::new(df)
```

## Rendering

**Without plotters** (`default-features = false`) — the self-contained SVG
backend, also used in the browser; zero rendering dependencies:

```rust
let svg: String = plot.render_svg_native_with_size(800, 600)?;
```

The remaining methods need the `plotters` feature (on by default). Save to a file (format inferred from the extension — `svg`, `png`, `jpg`, ...):

```rust
plot.save("out.svg")?;              // 800x600 default
plot.save_with_size("out.png", 1200, 800)?;
plot.ggsave("out.png", 6.0, 4.0, 150.0)?; // width_in, height_in, dpi
```

Or render in memory — no temp files — which is what you want when serving charts
from a web/MCP service:

```rust
let svg: String   = plot.clone().render_svg()?;          // or render_svg_with_size(w, h)
let png: Vec<u8>  = plot.render_png_with_size(400, 300)?; // fully-encoded PNG bytes
```

**Headless / no system fonts.** Rendering uses plotters' `ab_glyph` text backend
with a **bundled font** (DejaVu Sans), not `font-kit`/fontconfig — so text renders
deterministically in a minimal container with no system fonts installed. Nothing
to configure; there is no dependency on the host's font stack.

## Theming & brand color

Everything about a theme is set at **runtime**, so one render process can serve
many tenants' brands without touching chart code.

Inject a **brand/primary color** — it becomes the default for any single-series
geom that has no `color`/`fill` aesthetic mapped (an explicit mapping always wins):

```rust
GGPlot::new(data)
    .aes(Aes::new().x("day").y("count"))
    .geom_col()
    .primary_color((26, 153, 136)) // DataZoo teal — no per-chart color code
    .render_svg()?;
```

Build a whole `Theme` at runtime and compose the brand into it:

```rust
let theme = theme_minimal().with_primary((26, 153, 136));
GGPlot::new(data).aes(/* … */).geom_line().theme(theme);
```

Supply an **arbitrary sequential ramp** (e.g. a green→red risk score) instead of
the built-in viridis/brewer scales — pass explicit `(offset, color)` stops:

```rust
GGPlot::new(data)
    .aes(Aes::new().x("x").y("y").color("risk"))
    .geom_point()
    .scale_color_gradientn(vec![
        (0.0, RGBAColor::new(0, 160, 80)),   // low  = green
        (0.5, RGBAColor::new(240, 200, 0)),  // mid  = amber
        (1.0, RGBAColor::new(200, 40, 40)),  // high = red
    ]);
```

## Feature Flags

| Feature      | Default | Provides                                                    |
| ------------ | :-----: | ----------------------------------------------------------- |
| `polars`     |   yes   | `impl GGData for polars::DataFrame` + `polars` re-export     |
| `plotters`   |   yes   | plotters-backed `render_svg`, `render_png`, `save`, `ggsave`, `ggarrange_png` (implies `png`) |
| `png`        |  (yes)  | PNG encoding via `image` (pulled in by `plotters` and `canvas`) |
| `arrow`      |   no    | `impl GGData for arrow::RecordBatch` (Arrow/DuckDB input)    |
| `regression` |   no    | `stat_quantile`/`geom_quantile` + `geom_smooth` glm/rlm via anofox-regression |
| `serde`      |   no    | `theme::config::ThemeConfig` — a serde-deserialisable partial theme overlay (TOML/JSON) |
| `sf`         |   no    | `geom_sf` / `coord_sf` — render simple-features (WKT) geometry with projections; no extra deps |
| `geojson`    |   no    | read GeoJSON into a plot-ready frame (`spatial::geojson`); adds `serde_json` |
| `canvas`     |   no    | self-contained RGBA raster backend for large-N (`render_rgba`/`render_png_raster`); wasm-ok |
| `wasm`       |   no    | **deprecated** alias for `sf` (the browser bindings moved to the `crates/ggplot-rs-wasm` crate) |
| `cli`        |   no    | the `ggplot-rs` command-line tool (parquet/CSV/DuckDB → SVG/PNG), via clap + bundled DuckDB |

To skip the heavy polars and plotters dependencies (e.g. an Arrow-only service
that renders with `render_svg_native*`), disable defaults:

```toml
ggplot-rs = { version = "0.16", default-features = false, features = ["arrow"] }
```

With `default-features = false, features = ["sf"]` the whole dependency tree is
`ggplot-rs` + `indexmap` (+ its two dependencies).

## Examples

Run any example with:

```sh
cargo run --example scatter
cargo run --example histogram
cargo run --example bar_chart
cargo run --example continuous_color
cargo run --example density
cargo run --example faceted
cargo run --example loess_smooth
cargo run --example annotations
cargo run --example coord_flip
cargo run --example log_scale
cargo run --example color_palettes
cargo run --example gallery            # regenerates the gallery above
cargo run --example supplier_leadtime  # polars-free; runs with --no-default-features --features plotters
```

## Dependencies

- [indexmap](https://crates.io/crates/indexmap) 2 — ordered maps for internal data
- [plotters](https://crates.io/crates/plotters) 0.3 — SVG/PNG rendering (`ab_glyph` text backend; no fontconfig) *(optional, default)*
- [image](https://crates.io/crates/image) 0.24 — in-memory PNG encoding *(optional, via `plotters`/`canvas`)*
- [polars](https://crates.io/crates/polars) 0.46 — DataFrame input *(optional, default)*
- [arrow](https://crates.io/crates/arrow) 53 — Arrow `RecordBatch` input *(optional)*
- [clap](https://crates.io/crates/clap) 4 + [duckdb](https://crates.io/crates/duckdb) 1 (bundled) — the `cli` tool *(optional)*

## License

Licensed under either of

- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or <http://www.apache.org/licenses/LICENSE-2.0>)
- MIT license ([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.

### Bundled font

Bundled fonts in `assets/fonts/` — DejaVu **Sans** (+ Bold/Oblique), **Serif** (+ Bold/Italic), and **Sans Mono** (+ Bold) — give headless rendering for `family = "serif"`/`"monospace"` and bold/italic (`element_text(face=)`) with real glyphs, no fontconfig. DejaVu Sans
is distributed under a permissive, freely-redistributable license (Bitstream Vera
+ Arev) — see [`assets/fonts/LICENSE-DejaVu.txt`](assets/fonts/LICENSE-DejaVu.txt).