Creating sankey charts

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

The Sankey chart (Sankey chart) lets you add a specific type of flow chart to the sheet you are editing. The chart visually emphasizes major transfers or flows within defined system boundaries. The width of the chart arrows is shown proportionally to the flow quantity. The Sankey chart is included in the Visualization bundle.

• A minimum of two dimensions and one measure is required. You can use up to five dimensions, but only one measure.
• The dimensions do not need to be of equal size on each side of the diagram.
• You can use the dimension values to set the color of the flows in the chart.
• Link colors can be based on source or target anchor.

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

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

// Rendering a Sankey chart on the fly
nuked.render({
  type: "sankeychart",
  element: document.querySelector(".sankey"),
  fields: [
    "Region",
    "Product Group",
    "Product Type",
    "Product Line",
    "=Sum(Margin)",
  ],

  // overrides default properties
  properties: {
    node: {
      padding: 0.2,
      width: 0.3,
    },
    link: {
      opacity: 0.5,
      shadow: false,
      color: 3,
      colorBy: "custom",
    },
  },
});

Requirements

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

Installing

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

More examples

Node and link colors

You can change the node colors of each dimension value. The color should be a valid CSS color.

The colors of chart links are based on either the source or target anchors. To apply the source or target anchor color to chart links either use the string ='SOURCE' or ='TARGET'. You can also select a separate color by entering a color code string. The color should be a valid CSS color.

nuked.render({
  element: document.querySelector(".object"),
  type: "sankeyChart",
  properties: {
    node: {
      padding: 0.1,
      width: 0.7,
    },
    qHyperCubeDef: {
      qDimensions: [
        {
          qDef: {
            qFieldDefs: ["Region"],
          },
          qAttributeExpressions: [
            {
              qExpression:
                "if(Sum(total<Region> Margin) > 4500000, '#53ac94', '#ac536b')",
            },
          ],
        },
        {
          qDef: {
            qFieldDefs: ["Product Group"],
          },
          qAttributeExpressions: [
            {
              qExpression: "'#28bad7'",
            },
          ],
        },
      ],
      qMeasures: [
        {
          qDef: {
            qDef: "Sum(Margin)",
          },
          qAttributeExpressions: [
            {
              qExpression: "if(Sum(Margin) > 300000, '#53ac94', '#ac536b')",
            },
          ],
        },
      ],
      qInitialDataFetch: [
        {
          qLeft: 0,
          qTop: 0,
          qWidth: 6,
          qHeight: 1000,
        },
      ],
    },
  },
});

Links colored based on their source

nuked.render({
  element: document.querySelector(".object"),
  type: "sankeyChart",
  fields: ["Product Group", "Product Type"],
  properties: {
    qHyperCubeDef: {
      qDimensions: [
        {
          qDef: {
            qFieldDefs: ["Region"],
          },
          qAttributeExpressions: [
            {
              qExpression:
                "if(Sum(total<Region> Margin) > 4500000, '#53ac94', '#ac536b')",
            },
          ],
        },
      ],
      qMeasures: [
        {
          qDef: {
            qDef: "Sum(Margin)",
          },
          qAttributeExpressions: [
            {
              qExpression: "='SOURCE'",
            },
          ],
        },
      ],
      qInitialDataFetch: [
        {
          qLeft: 0,
          qTop: 0,
          qWidth: 6,
          qHeight: 1000,
        },
      ],
    },
  },
});

Sankey chart plugins

A plugin can be passed into a Sankey 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

// Adding a text component
const textPlugin = {
  info: {
    name: "text-plugin",
    type: "component-definition",
  },
  fn: ({ layout, keys }) => {
    const componentDefinition = {
      type: "text",
      key: "my-text",
      text: "Sales of Clothes in Different Areas",
      layout: { dock: "top" },
    };
    return componentDefinition;
  },
};

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

// Rendering a Sankey chart with plugins
nuked.render({
  element: document.getElementById("object"),
  type: "sn-sankey-chart",
  fields: ["CategoryName", "Region", "=Sum(Sales)"],
  plugins: [textPlugin], // eslint-disable-line no-undef
});

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: { DIMENSIONS },
    COMPONENT: { LABELS_TITLES, LABELS },
  },
};

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

Add new components

The new component can be a standard Picasso component or a custom Picasso component. Below is a standard text component which add a label at the top center of the chart.

// Adding a text component
const textPlugin = {
  info: {
    name: "text-plugin",
    type: "component-definition",
  },
  fn: ({ layout, keys }) => {
    const componentDefinition = {
      type: "text",
      key: "my-text",
      text: "Sales of Clothes in Different Areas",
      layout: { dock: "top" },
    };
    return componentDefinition;
  },
};

Modify existing components

As an example, the appearance of the labels 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.LABELS in this example).

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

      // Provide the same name as the exisiting component to override it
      key: keys.COMPONENT.LABELS,
      settings: {
        sources: [
          {
            component: "san",
            selector: ".labelCenter",
            strategy: {
              type: "rows",
              settings: {
                align: 0.5,
                justify: 0.5,
                padding: 4,
                labels: [{}, {}],
              },
            },
          },
          {
            component: "san",
            selector: ".labelLeft",
            strategy: {
              type: "rows",
              settings: {
                align: 0,
                justify: 0.5,
                padding: 4,
                fontFamily: "Helvetica",
                fontSize: "14",
                fill: "darkgreen",
              },
            },
          },
          {
            component: "san",
            selector: ".labelRight",
            strategy: {
              type: "rows",
              settings: {
                align: 1,
                justify: 0.5,
                padding: 4,
                fontFamily: "Helvetica",
                fontSize: "14",
                fill: "darkred",
              },
            },
          },
        ],
      },
    };
    return componentDefinition;
  },
};

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.