Skip to main content
Renders a two-dimensional grid of colored cells. Cell color encodes the numeric value — each cell is mapped through a ColorMap after normalizing values to [0.0, 1.0] relative to the data range. A colorbar is always shown in the right margin.

​
Constructor

​
new()

Create a heatmap with default settings. Returns: Heatmap Defaults:
  • Viridis color map
  • No value overlay
  • No labels
use kuva::plot::Heatmap;

let heatmap = Heatmap::new();

​
Data Loading

​
with_data()

Set the grid data.
​
data
I: IntoIterator<Item = T>
Accepts any iterable of iterables of numeric values. The outer iterator produces rows (top to bottom); the inner iterator produces columns (left to right). All rows must have the same number of columns.
Returns: Self 
let heatmap = Heatmap::new().with_data(vec![
    vec![1.0, 2.0, 3.0],
    vec![4.0, 5.0, 6.0],
]);

​
Labels

​
with_labels()

Store row and column label strings in the struct.
​
rows
Vec<String>
Row label strings
​
cols
Vec<String>
Column label strings
Returns: Self Note: These labels are not rendered automatically. To display them on the axes, pass them to Layout::with_y_categories (rows) and Layout::with_x_categories (columns) when building the layout. 
let heatmap = Heatmap::new()
    .with_data(vec![vec![1.0, 2.0], vec![3.0, 4.0]])
    .with_labels(
        vec!["Row1".into(), "Row2".into()],
        vec!["Col1".into(), "Col2".into()]
    );

​
Styling

​
with_color_map()

Set the color map used to encode cell values.
​
map
ColorMap
Color map applied after normalizing values to [0.0, 1.0]. Options: ColorMap::Viridis (default), ColorMap::Inferno, ColorMap::Grayscale, or ColorMap::Custom(Arc<Fn>)
Returns: Self Default: ColorMap::Viridis 
use kuva::plot::ColorMap;

let heatmap = Heatmap::new()
    .with_data(vec![vec![1.0, 2.0], vec![3.0, 4.0]])
    .with_color_map(ColorMap::Inferno);

​
with_values()

Overlay numeric values inside each cell. Returns: Self Values are formatted to two decimal places and centered in the cell. Most useful for small grids where the text remains legible. 
let heatmap = Heatmap::new()
    .with_data(vec![vec![1.0, 2.0], vec![3.0, 4.0]])
    .with_values();

​
Legend

​
with_legend()

Attach a legend label to this heatmap.
​
label
S: Into<String>
Legend label text
Returns: Self 
let heatmap = Heatmap::new()
    .with_data(vec![vec![1.0, 2.0], vec![3.0, 4.0]])
    .with_legend("Expression");

​
Complete Example

use kuva::plot::{Heatmap, ColorMap};
use kuva::backend::svg::SvgBackend;
use kuva::render::render::render_multiple;
use kuva::render::layout::Layout;
use kuva::render::plots::Plot;

let data = vec![
    vec![0.8, 0.3, 0.9],
    vec![0.4, 0.7, 0.1],
    vec![0.5, 0.9, 0.4],
];

let heatmap = Heatmap::new()
    .with_data(data)
    .with_color_map(ColorMap::Viridis);

let plots = vec![Plot::Heatmap(heatmap)];
let layout = Layout::auto_from_plots(&plots)
    .with_title("Heatmap")
    .with_x_categories(vec!["A".into(), "B".into(), "C".into()])
    .with_y_categories(vec!["X".into(), "Y".into(), "Z".into()]);

let svg = SvgBackend.render_scene(&render_multiple(plots, layout));
std::fs::write("heatmap.svg", svg).unwrap();

​
Public Fields

​
data
Vec<Vec<f64>>
Rows × columns grid of values. All rows must have the same length.
​
row_labels
Option<Vec<String>>
Optional row labels — stored in the struct but rendered via Layout::with_y_categories
​
col_labels
Option<Vec<String>>
Optional column labels — stored in the struct but rendered via Layout::with_x_categories
​
color_map
ColorMap
Color map applied after normalizing values to [0.0, 1.0]. Defaults to ColorMap::Viridis
​
show_values
bool
When true, each cell displays its raw numeric value as text
​
legend_label
Option<String>
Optional legend label

Build docs developers (and LLMs) love

Get started for freeTalk to us