Ridgeline Plot

A ridgeline plot (also called a joyplot) stacks multiple KDE density curves vertically — one per group. Groups are labelled on the y-axis; the x-axis is the continuous data range. Curves can overlap for the classic "mountain range" look.

Basic usage

#![allow(unused)]
fn main() {
use kuva::plot::ridgeline::RidgelinePlot;
use kuva::render::plots::Plot;
use kuva::render::layout::Layout;
use kuva::render::render::render_multiple;
use kuva::backend::svg::SvgBackend;

let plot = RidgelinePlot::new()
    .with_group("Control",     vec![1.2, 1.5, 1.8, 2.0, 2.2, 1.9, 1.6, 1.3])
    .with_group("Treatment A", vec![2.5, 3.0, 3.5, 4.0, 3.8, 3.2, 2.8, 3.6])
    .with_group("Treatment B", vec![4.5, 5.0, 5.5, 6.0, 5.8, 5.2, 4.8, 5.3]);

let plots = vec![Plot::Ridgeline(plot)];
let layout = Layout::auto_from_plots(&plots)
    .with_title("Expression by Treatment")
    .with_x_label("Expression Level")
    .with_y_label("Group");
let svg = SvgBackend.render_scene(&render_multiple(plots, layout));
}

Per-group colors — seasonal temperature example

.with_group_color(label, data, color) lets you assign an explicit color to each group. A cold-to-warm gradient across months gives the plot an intuitive thermal feel.

#![allow(unused)]
fn main() {
use kuva::plot::ridgeline::RidgelinePlot;
use kuva::render::plots::Plot;
use kuva::render::layout::Layout;
use kuva::render::render::render_multiple;
use kuva::backend::svg::SvgBackend;

// (month, mean °C, std-dev) for a temperate-climate city
let months = [
    ("January",   -3.0_f64, 5.0_f64),
    ("February",  -1.5,     5.5),
    ("March",      4.0,     5.0),
    ("April",     10.0,     4.0),
    ("May",       15.5,     3.5),
    ("June",      20.0,     3.0),
    ("July",      23.0,     2.5),
    ("August",    22.5,     2.5),
    ("September", 17.0,     3.0),
    ("October",   10.5,     4.0),
    ("November",   3.5,     5.0),
    ("December",  -1.0,     5.5),
];

// Blue → red gradient (cold → hot)
let colors = [
    "#3a7abf", "#4589c4", "#6ba3d4", "#a0bfdc",
    "#d4b8a0", "#e8c97a", "#f0a830", "#e86820",
    "#d44a10", "#c06030", "#9070a0", "#5060b0",
];

let mut plot = RidgelinePlot::new()
    .with_overlap(0.6)
    .with_opacity(0.75);

for (i, &(month, mean, std)) in months.iter().enumerate() {
    let data: Vec<f64> = vec![/* 200 samples from N(mean, std) */];
    plot = plot.with_group_color(month, data, colors[i]);
}

let plots = vec![Plot::Ridgeline(plot)];
let layout = Layout::auto_from_plots(&plots)
    .with_title("Daily Temperature Distributions by Month")
    .with_x_label("Temperature (°C)")
    .with_y_label("Month");
let svg = SvgBackend.render_scene(&render_multiple(plots, layout));
}

CLI

kuva ridgeline samples.tsv --group-by group --value expression \
    --title "Ridgeline" --x-label "Expression"

Builder reference