Creating grid charts

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

The grid chart uses symbols of varying size sorted in a grid to visualize a measure across two dimensions. The measure is the metric that determines the size of the symbol in each crossing.

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

grid chart example 
// Configure nucleus
const nuked = window.stardust.embed(app, {
  context: { theme: "light" },
  types: [
    {
      name: "sn-grid-chart",
      load: () => Promise.resolve(window["sn-grid-chart"]),
    },
  ],
});


// Rendering a simple grid chart
nuked.render({
  element: document.querySelector(".grid"),
  type: "sn-grid-chart",
  fields: ["Country", "Year", "=Sum(Population)"],
  properties: {
    title: "The historical populations of some European countries",
  },
});

Requirements

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

Installing

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

More examples

Change symbol size and shape

The size and shape of the symbols can be modified.

grid chart example - symbol 
// Rendering a grid chart with customized symbols
nuked.render({
  element: document.querySelector(".grid"),
  type: "sn-grid-chart",
  // fields: ['Country', 'Year', '=Sum(Population)'],
  properties: {
    title: "The historical populations of some European countries",
    dataPoint: {
      rangeBubbleSizes: [0.25, 0.85],
      symbol: "star",
    },
  },
});

Customize the look of the chart

You can color the symbol by measure and add a legend to show more information about the measure. The axis titles can be hidden and the gridlines can be shown to further improve the look.

grid chart example - coloring 
// Rendering a customized grid chart
nuked.render({
  element: document.querySelector(".grid"),
  type: "sn-grid-chart",


  // Define all `fields` in `properties`
  properties: {
    title: "The historical populations of some European countries",
    qHyperCubeDef: {
      qDimensions: [
        {
          qDef: { qFieldDefs: ["Country"] },
        },
        {
          qDef: { qFieldDefs: ["Year"] },


          qAttributeExpressions: [
            {
              qExpression: "Sum(Population)",
              id: "colorByAlternative",
            },
          ],
        },
      ],
      qMeasures: [
        {
          qDef: {
            qDef: "Sum(Population)",
          },
        },
      ],
      qMode: "T",
      qAlwaysFullyExpanded: true,
    },
    color: {
      auto: false,
      mode: "byMeasure",
      measureScheme: "dg",
      reverseScheme: true,
    },
    legend: {
      show: true,
      dock: "auto",
      showTitle: true,
    },
    xAxis: {
      show: "label",
      dock: "near",
      gridLines: true,
    },
    yAxis: {
      show: "label",
      dock: "near",
      gridLines: true,
    },
  },
});

Grid chart plugins

A plugin can be passed into a grid 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 existing point component
const pointPlugin = {
  info: {
    name: "point-plugin",
    type: "component-definition",
  },
  fn: ({ layout, keys }) => {
    const componentDefinition = {
      type: "point",


      // Provide the same name as the existing point component to override it
      key: keys.COMPONENT.POINT,
      settings: {
        strokeWidth: "2px",
        stroke: "dimgray",


        // Using data property 'd' and layout as input for helper functions
        size: (d) => getSizeInLogarithmScale(d, layout),
        fill: (d) => getColorBasedOnMedian(d),
      },
    };
    return componentDefinition;
  },
};


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


// Rendering a grid chart with plugins
nuked.render({
  element: document.getElementById("object"),
  type: "sn-grid-chart",
  fields: ["Country", "Year", "=Sum(Population)"],
  plugins: [pointPlugin],
  properties: {
    title: "The historical population of some European countries",
  },
});

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: {
      X,
      Y,
    },
    COMPONENT: {
      X_AXIS,
      Y_AXIS,
      POINT,
    },
    COLLECTION: {
      MAIN,
    },
  },
};

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

Add new components

The new component can be a standard Picasso component or a custom Picasso component. Below is a custom component which add labels next to the grid bubbles.

grid chart labels plugin 
// Implementing a custom labels plugin, so that we can use it later
const labelsPluginDefinition = {
  info: {
    componentName: "custom-labels-plugin",
    name: "custom-labels-plugin",
    type: "custom-component",
  },
  fn: () => {
    const implementation = {
      require: ["chart", "renderer"],
      render() {
        const { items } = this.chart.component("point-component").data;
        const scale = this.chart.scales();
        const { width, height } = this.rect;
        const labels = items.map((item) => ({
          type: "text",
          text: item.size.label,
          x: (scale.x(item.x.value) + scale.x.bandwidth() * 0.5) * width,
          y: (scale.y(item.y.value) + scale.y.bandwidth() * 0.2) * height,
          anchor: "middle",
          fill: "red",
          fontSize: "14ppx",
        }));
        return labels;
      },
    };
    return implementation;
  },
};


// Using the labels plugin, defined above
const labelsPlugin = {
  info: {
    name: "labels",
    type: "component-definition",
  },
  fn: ({ keys }) => {
    const componentDefinition = {
      // The type has to match with the componentName of the labels plugin definition above
      type: "custom-labels-plugin",
      key: "my-labels",
    };
    return componentDefinition;
  },
};

Modify existing components

As an example, the positions and the appearance of the axes 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.X_AXIS in this example).

grid chart x-axis plugin 
// Modifying the look and the position of the x-axis
const xAxisPlugin = {
  info: {
    name: "x-axis-plugin",
    type: "component-definition",
  },
  fn: ({ keys, layout }) => {
    const componentDefinition = {
      type: "axis",


      // Provide the same name as the existing x-axis component to override it
      key: keys.COMPONENT.X_AXIS,
      layout: { dock: "top" },
      settings: {
        labels: {
          fontFamily: "Cambria, serif",
          fontSize: "15px",
          fill: "dimgray",
        },
        line: { stroke: "gray" },
      },
    };
    return componentDefinition;
  },
};


// y-axis plugin can be defined with similar code
// ...

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.
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