Creating pie charts

Note: Where possible, use qlik-embed and qlik/api rather than this framework.

A pie chart is a circular chart divided into more slices that each represent a proportion of the whole. Pie charts are most visually efficient when a small number (10 or fewer) of slices is displayed.

Learn more about the pie chart, or review the pie chart API specification.

// Configure nucleus
const nuked = window.stardust.embed(app, {
  context: { theme: "light" },
  types: [
    {
      name: "pie-chart",
      load: () => Promise.resolve(window["sn-pie-chart"]),
    },
  ],
});
// Rendering a pie chart on the fly
nuked.render({
  element: document.querySelector(".pie"),
  type: "pie-chart",
  fields: ["Year", "=Avg(Price)"],

  // Overrides default properties
  properties: {
    title: "Price of Cars by Year",
    dataPoint: {
      labelMode: "none",
    },
  },
});

In a pie chart you need at least one dimension and one measure. The dimension determines what kind of data is represented on the slices. The measure determines the angle of each slice. A second measure can be added, this one determines the radius of the slices.

Two types of pie chart views are available: the traditional pie chart and the hollow-centered donut chart.

Requirements

Requires @nebula.js/stardust version 1.2.0 or later.

Installing

If you use npm: npm install @nebula.js/sn-pie-chart. You can also load through the script tag directly from https://unpkg.com.

Examples

The examples below show some possible configurations for the pie chart.

One dimension, one measure, value labels

nuked.render({
  element: document.querySelector(".pie"),
  type: "pie-chart",
  fields: ["Country", "=Avg(Price)"],

  // Overrides default properties
  properties: {
    title: "Price of Cars by Country",
    dataPoint: {
      labelMode: "value",
    },
  },
});

One dimension, two measures, percentage labels

nuked.render({
  element: document.querySelector(".pie"),
  type: "pie-chart",
  fields: ["Country", "=Avg(Price)", "=Avg(Horsepower)"],

  // Overrides default properties
  properties: {
    title: "Price and horsepower by country",
    dataPoint: {
      labelMode: "share",
    },
  },
});

One dimension, one measure, donut chart view

nuked.render({
  element: document.querySelector(".pie"),
  type: "pie-chart",
  fields: ["Country", "=Avg(Price)"],

  // Overrides default properties
  properties: {
    title: "Price by country",
    dataPoint: {
      labelMode: "share",
    },
    donut: {
      showAsDonut: true,
    },
  },
});

One dimension, two measures, donut chart view

nuked.render({
  element: document.querySelector(".pie"),
  type: "pie-chart",
  fields: ["Country", "=Avg(Price)", "=Avg(Horsepower)"],

  // Overrides default properties
  properties: {
    title: "Price and horsepower by country",
    dataPoint: {
      labelMode: "share",
    },
    donut: {
      showAsDonut: true,
    },
  },
});

Pie chart plugins

A plugin can be passed into a pie chart to add or modify its capability or visual appearance. A plugin needs to be defined before it can be rendered together with the chart.

// Step 1: define the plugin

// Modifying the look of the dimension title component
const totalPopulationLabelPlugin = {
  info: {
    name: "total-title-plugin",
    type: "component-definition",
  },
  fn: ({ keys, layout }) => {
    const componentDefinition = {
      type: "text",
      text: "World Total: 7.9 Billions",
      layout: { dock: "bottom" },
    };
    return componentDefinition;
  },
};

// Step 2: passing the plugin definition into the render function

// Render a pie chart with plugins
nuked.render({
  element: document.querySelector("#object"),
  type: "sn-pie-chart",
  plugins: [totalPopulationLabelPlugin],
  fields: ["Country", "=Sum(Population)"],
  properties: {
    dataPoint: { labelMode: "value" },
  },
});

The plugin definition is an object, with two properties info and fn. The fn returns a picasso.js component. To build this component, some important chart internals are passed into the argument object of fn.

// Structure of the argument object of fn
const pluginArgs = {
  layout,
  keys: {
    SCALE: { FILL },
    COMPONENT: { DIMENSION_TITLE, SLICES, PIE_LABELS },
  },
};

With plugins, you can either add new components or modify existing components of the pie chart.

Modify existing components

As an example, the appearance of the slices can be modified by plugins.

To override an existing component, fn should returns a picasso.js component that has the same key as the existing component (keys.COMPONENT.SLICES in this example).

// Modifying the look of the slices component
const slicesPlugin = {
  info: {
    name: "pie-plugin",
    type: "component-definition",
  },
  fn: ({ keys, layout }) => {
    const componentDefinition = {
      type: "pie",

      // Provide the same name as the exisiting component to override it
      key: keys.COMPONENT.SLICES,
      settings: {
        slice: {
          innerRadius: 0.6,
          strokeWidth: 0,
          stroke: "red",
          outerRadius: 0.8,
          cornerRadius: 2,
        },
      },
    };
    return componentDefinition;
  },
};

Add new components

The new component can be a standard Picasso component or a custom Picasso component. The code for adding a new component is similar to that for modifying an existing component, the only difference is that the key should be different from that of any of the existing components.

Plugins disclaimer

• The plugins API is still experimental.
• It is not guaranteed that the chart is compatible with all different settings, especially when modifying existing components.