Chart.js Box and Violin Plot

Chart.js module for charting box and violin plots. This is a maintained fork of @datavisyn/chartjs-chart-box-and-violin-plot, which I originally developed during my time at datavisyn.

Works only with Chart.js >= 3.0.0

Install

npm install --save chart.js@next @sgratzl/chartjs-chart-boxplot@next

Usage

see Samples on Github

and

Chart

four new types: boxplot, horizontalBoxplot, violin, and horizontalViolin.

Config

The config can be done on a per dataset .data.datasets[0].minStats or for all datasets under the controllers name. e.g., .options.boxplot.datasets.minStats.

Data structure

Both types support that the data is given as an array of numbers number[]. The statistics will be automatically computed. In addition, specific summary data structures are supported:

interface IBaseItem {
  min: number;
  median: number;
  max: number;
  /**
   * values of the raw items used for rendering jittered background points
   */
  items?: number[];
}

interface IBoxPlotItem extends IBaseItem {
  q1: number;
  q3: number;
  whiskerMin?: number;
  whiskerMax?: number;
  /**
   * list of box plot outlier values
   */
  outliers?: number[];
}

interface IKDESamplePoint {
  /**
   * sample value
   */
  v: number;
  /**
   * sample estimation
   */
  estimate: number;
}

interface IViolinItem extends IBaseItem {
  /**
   * samples of the underlying KDE
   */
  coords: IKDESamplePoint[];
}

Tooltips

In order to simplify the customization of the tooltips the tooltip item given to the tooltip callbacks was improved. The default toString() behavior should be fine in most cases. The tooltip item has the following structure:

interface ITooltipItem {
  label: string; // original
  value: {
    raw: IBoxPlotItem | IViolinItem;
    /**
     * in case an outlier is hovered this will contains its index
     * @default -1
     */
    hoveredOutlierRadius: number;
    /**
     * toString function with a proper default implementation, which is used implicitly
     */
    toString(): string;

    min: string;
    median: string;
    max: string;
    items?: string[];

    //... the formatted version of different attributes IBoxPlotItem or ViolinItem
  };
}

ESM and Tree Shaking

The ESM build of the library supports tree shaking thus having no side effects. As a consequence the chart.js library won't be automatically manipulated nor new controllers automatically registered. One has to manually import and register them.

Variant A:

import Chart from 'chart.js';
import { BoxPlotController } from '@sgratzl/chartjs-chart-boxplot';

// register controller in chart.js and ensure the defaults are set
BoxPlotController.register();
...

new Chart(ctx, {
  type: BoxPlotController.id,
  data: [...],
});

Variant B:

import { BoxPlotChart } from '@sgratzl/chartjs-chart-boxplot';

new BoxPlotChart(ctx, {
  data: [...],
});

Development Environment

npm i -g yarn
yarn set version 2.1.0
yarn
yarn pnpify --sdk vscode

Building

yarn install
yarn build

Credits

Originally credits belong to @datavisyn.