129 lines
4.6 KiB
Markdown
129 lines
4.6 KiB
Markdown
# Polar Area
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Polar area charts are similar to pie charts, but each segment has the same angle - the radius of the segment differs depending on the value.
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This type of chart is often useful when we want to show a comparison data similar to a pie chart, but also show a scale of values for context.
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{% chartjs %}
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{
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"type": "polarArea",
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"data": {
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"labels": [
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"Red",
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"Green",
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"Yellow",
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"Grey",
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"Blue"
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],
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"datasets": [{
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"label": "My First Dataset",
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"data": [11, 16, 7, 3, 14],
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"backgroundColor": [
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"rgb(255, 99, 132)",
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"rgb(75, 192, 192)",
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"rgb(255, 205, 86)",
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"rgb(201, 203, 207)",
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"rgb(54, 162, 235)"
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]
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}]
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}
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}
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{% endchartjs %}
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## Example Usage
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```javascript
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new Chart(ctx, {
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data: data,
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type: 'polarArea',
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options: options
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});
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```
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## Dataset Properties
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The following options can be included in a polar area chart dataset to configure options for that specific dataset.
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| Name | Type | [Scriptable](../general/options.md#scriptable-options) | [Indexable](../general/options.md#indexable-options) | Default
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| ---- | ---- | :----: | :----: | ----
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| [`backgroundColor`](#styling) | [`Color`](../general/colors.md) | Yes | Yes | `'rgba(0, 0, 0, 0.1)'`
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| [`borderAlign`](#border-alignment) | `string` | Yes | Yes | `'center'`
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| [`borderColor`](#styling) | [`Color`](../general/colors.md) | Yes | Yes | `'#fff'`
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| [`borderWidth`](#styling) | `number` | Yes | Yes | `2`
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| [`data`](#data-structure) | `number[]` | - | - | **required**
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| [`hoverBackgroundColor`](#interations) | [`Color`](../general/colors.md) | Yes | Yes | `undefined`
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| [`hoverBorderColor`](#interactions) | [`Color`](../general/colors.md) | Yes | Yes | `undefined`
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| [`hoverBorderWidth`](#interactions) | `number` | Yes | Yes | `undefined`
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### Styling
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The style of each arc can be controlled with the following properties:
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| Name | Description
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| ---- | ----
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| `backgroundColor` | arc background color.
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| `borderColor` | arc border color.
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| `borderWidth` | arc border width (in pixels).
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All these values, if `undefined`, fallback to the associated [`elements.arc.*`](../configuration/elements.md#arc-configuration) options.
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### Border Alignment
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The following values are supported for `borderAlign`.
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* `'center'` (default)
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* `'inner'`
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When `'center'` is set, the borders of arcs next to each other will overlap. When `'inner'` is set, it is guaranteed that all the borders are not overlap.
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### Interactions
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The interaction with each arc can be controlled with the following properties:
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| Name | Description
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| ---- | -----------
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| `hoverBackgroundColor` | arc background color when hovered.
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| `hoverBorderColor` | arc border color when hovered.
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| `hoverBorderWidth` | arc border width when hovered (in pixels).
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All these values, if `undefined`, fallback to the associated [`elements.arc.*`](../configuration/elements.md#arc-configuration) options.
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## Config Options
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These are the customisation options specific to Polar Area charts. These options are merged with the [global chart default options](#default-options), and form the options of the chart.
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| Name | Type | Default | Description
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| ---- | ---- | ------- | -----------
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| `startAngle` | `number` | `-0.5 * Math.PI` | Starting angle to draw arcs for the first item in a dataset.
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| `animation.animateRotate` | `boolean` | `true` | If true, the chart will animate in with a rotation animation. This property is in the `options.animation` object.
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| `animation.animateScale` | `boolean` | `true` | If true, will animate scaling the chart from the center outwards.
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## Default Options
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We can also change these defaults values for each PolarArea type that is created, this object is available at `Chart.defaults.polarArea`. Changing the global options only affects charts created after the change. Existing charts are not changed.
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For example, to configure all new polar area charts with `animateScale = false` you would do:
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```javascript
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Chart.defaults.polarArea.animation.animateScale = false;
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```
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## Data Structure
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For a polar area chart, datasets need to contain an array of data points. The data points should be a number, Chart.js will total all of the numbers and calculate the relative proportion of each.
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You also need to specify an array of labels so that tooltips appear correctly for each slice.
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```javascript
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data = {
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datasets: [{
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data: [10, 20, 30]
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}],
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// These labels appear in the legend and in the tooltips when hovering different arcs
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labels: [
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'Red',
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'Yellow',
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'Blue'
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]
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};
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```
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