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Nested Donut

Nested Donut

Nested Donut is a variation of our Donut component that supports hierarchical data. Similar to a traditional Sunburst chart, Nested Donut displays hierarchies through a series of a rings or layers containing categorical nodes or segments.

Data​

Nested Donut expects an array of generic data records, the properties of which will be used to define the layers. Each layer will contain nodes or segments that represent their corresponding quantity in the data array.

For the following examples, assume data is of type Datum[].

type Datum = {
  group: string;
  subgroup: string;
};

Defining Layers​

The layers property accepts an array of string accessor functions based on the Datum provided. The first accessor will define the outermost layer of the chart, the second will provide the next, and so on. We can provide layers with accessors such the group property defines parent nodes with subgroup children.

component.tsx
import { VisSingleContainer, VisNestedDonut } from '@unovis/react'

function Component(props) {
  const data: Datum[] = props.data
  const layers = [(d: Datum) => d.group, (d: Datum) => d.subgroup]

  return (
    <VisSingleContainer data={data}>
      <VisNestedDonut layers={layers}/>
    </VisSingleContainer>
  )
}
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Layers with missing/undefined data​

Now consider data where value is optional and only groups A and B have corresponding value properties. We see the hierarchical data is as expected, where the C group does not have child segments in the inner layer:

layers = [(d: Datum) => d.group, (d: Datum) => d.value]
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Segment Values​

By default, segment lengths are assigned based on the number of occurrences within the data array. For example, consider the following data provided to a single layer:

const data = ['A', 'A', 'A', 'B', 'B', 'C']

We would expect the values of A, B, and C to be proportional to their counts within in the array, i.e. 3, 2, and 1, respectively.

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Custom value Accessor​

Alternatively, you can override the default way Nested Donut calculates values by providing your own value accessor function. For example, f your data is shaped like:

const data = [{ label: 'A', value: 3 }, { label: 'B', value: 2 }, { label: 'C', value: 1 }]

you can provide value with (d: Datum) => d.value to achieve the same effect.

Layer Settings​

You can customize the appearance for each individual layer with the layerSettings property, which accepts an accessor that returns the following type based on the layer's depth:

type NestedDonutLayerSettings = {
  width: number | string; // The layer's width in pixels or css string to be converted to pixels
  labelAlignment: NestedDonutSegmentLabelAlignment; // Alignment of the layer's segment labels
}

Default Values​

By default, each layer has the same NestedDonutLayerSettings object with the following values:

{
  width: 50,
  labelAlignment: NestedDonutSegmentLabelAlignment.Perpendicular;
}

Label Alignment​

The labelAlignment property specifies how the segment labels will align based on their radial position. The possible values are:

  • NestedDonutSegmentLabelAlignment.Along - label is rotated with respect to the segment angle
  • NestedDonutSegmentLabelAlignment.Perpendicular - label is rotated perpendicular to the segment angle (default)
  • NestedDonutSegmentLabelAlignment.Straight - no rotation is applied
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Variable Layer Settings​

To set different layer settings depending on the layer, provide an NestedDonutLayerSettings accessor function with a numeric parameter. The number refers to the layer's index in the provided layers property.

layers = [(d: Datum) => d.group, (d: Datum) => d.subgroup]

// The accessor function that takes a layer index and returns a `NestedDonutLayerSettings` object:
layerSettings = (layer: number) => {
  if (i === 0) {
    return { width: 25 }
  }
}
component.tsx
import { VisSingleContainer, VisNestedDonut } from '@unovis/react'

function Component(props) {
  const data: Datum[] = props.data
  const layers = [(d: Datum) => d.group, (d: Datum) => d.subgroup]
  const layerSettings = (i: number) => i === 0 && {width : 25}

  return (
    <VisSingleContainer data={data}>
      <VisNestedDonut layers={layers} layerSettings={layerSettings}/>
    </VisSingleContainer>
  )
}
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Layer Padding​

You can provide a constant numeric value to layerPadding to set the spacing between each layer in pixels.

<VisNestedDonut layers={layers} layerPadding={10}/>
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Segments​

Segment Datum​

Unlike our non-hierarchical components, the data type used by accessors to customize segments will not resemble the Datum type because the segments are generated based on the collection of Datum objects provided.

So for certain properties that customize segments, accessors will deal with the following type:

type NestedDonutSegmentDatum<Datum> = {
  key: Datum[keyof Datum] // the category based on the current layer
  root: Datum[keyof Datum] // the highest parent node
}

type NestedDonutSegment<Datum> = {
  data: NestedDonutSegmentDatum<Datum>;
  depth: number;
  height: number;
  value: number;
}

Segment Color​

As an example, we can provide color property with an accessor that returns the color based on the segment's root:

export const groupColors = {
  A: 'red',
  B: 'green',
  C: 'blue',
}
segmentColor = (d: NestedDonutSegment<Datum>) => groupColors[d.data.root]

This gives us the appearance of three distinct colors based on the segment's group instead of the default shading:

<VisNestedDonut layers={layers} segmentColor={segmentColor}/>
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Segment Labels​

You can customize a segment's labels with the following properties: segmentLabel and segmentLabelColor:

const segmentColor = '#ddd'
const segmentLabel = (d: Datum) => {
  switch (d.data.key) {
    case 'A':
      return 'Alpha'
    case 'B':
      return 'Beta'
    case 'C':
      return 'Charlie'
      return d.data.key
  }
}
const segmentLabelColor = (d: Datum) => groupColors[d.data.root]
<VisNestedDonut
  layers={layers} 
  segmentColor="#ddd" 
  segmentLabel={segmentLabel} 
  segmentLabelColor={segmentLabelColor}
/>
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Direction​

By default, Nested Donut will form layers starting with the outermost layer and work inward towards the center. You can use the NestedDonutDirection.Outwards or 'outwards' to the direction property to get a Nested Donut that resembles a traditional Sunburst diagram:

<VisNestedDonut layers={layers} direction="outwards"/>
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Further configuration​

Nested Donut shares the following properties with our traditional Donut chart. Read Donut's doc page to learn more.

  • angleRange
  • centralLabel
  • centralSubLabel
  • emptySegmentLabel
  • showBackground
  • showEmptySegments

CSS Variables​

Nested Donut supports the following CSS variables:

/* Undefined by default to allow proper fallback to var(--vis-font-family) */
--vis-nested-donut-font-family: undefined;

/* Background */
--vis-nested-donut-background-color: #e7e9f3

/* Central label */
--vis-nested-donut-central-label-font-size: 16px;
--vis-nested-donut-central-label-font-weight: 600;
--vis-nested-donut-central-label-text-color: #5b5f6d;

/* Central sub-label */
--vis-nested-donut-central-sublabel-font-size: 12px;
--vis-nested-donut-central-sublabel-font-weight: 500;
--vis-nested-donut-central-sublabel-text-color: #5b5f6d;

/* Segments */
--vis-nested-donut-segment-stroke-width: 1px;
--vis-nested-donut-segment-stroke-color: var(--vis-nested-donut-background-color);
--vis-nested-donut-segment-label-text-color-light: #5b5f6d;
--vis-nested-donut-segment-label-text-color-dark: #fff;
--vis-nested-donut-segment-label-font-size: 1em;

/* Dark theme */
--vis-dark-nested-donut-background-color: #18160c;
--vis-dark-nested-donut-central-label-text-color: #fff;
--vis-dark-nested-donut-central-sublabel-text-color: #fff;

Component Props​

NameTypeDescription
* required property