45 lines
2.1 KiB
Markdown
45 lines
2.1 KiB
Markdown
# Labeling Axes
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When creating a chart, you want to tell the viewer what data they are viewing. To do this, you need to label the axis.
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## Scale Title Configuration
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The scale label configuration is nested under the scale configuration in the `scaleLabel` key. It defines options for the scale title. Note that this only applies to cartesian axes.
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| Name | Type | Default | Description
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| ---- | ---- | ------- | -----------
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| `display` | `boolean` | `false` | If true, display the axis title.
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| `labelString` | `string` | `''` | The text for the title. (i.e. "# of People" or "Response Choices").
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| `lineHeight` | <code>number|string</code> | `1.2` | Height of an individual line of text (see [MDN](https://developer.mozilla.org/en-US/docs/Web/CSS/line-height)).
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| `fontColor` | `Color` | `'#666'` | Font color for scale title.
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| `fontFamily` | `string` | `"'Helvetica Neue', 'Helvetica', 'Arial', sans-serif"` | Font family for the scale title, follows CSS font-family options.
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| `fontSize` | `number` | `12` | Font size for scale title.
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| `fontStyle` | `string` | `'normal'` | Font style for the scale title, follows CSS font-style options (i.e. normal, italic, oblique, initial, inherit).
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| `padding` | <code>number|object</code> | `4` | Padding to apply around scale labels. Only `top` and `bottom` are implemented.
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## Creating Custom Tick Formats
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It is also common to want to change the tick marks to include information about the data type. For example, adding a dollar sign ('$'). To do this, you need to override the `ticks.callback` method in the axis configuration.
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In the following example, every label of the Y axis would be displayed with a dollar sign at the front.
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If the callback returns `null` or `undefined` the associated grid line will be hidden.
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```javascript
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var chart = new Chart(ctx, {
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type: 'line',
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data: data,
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options: {
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scales: {
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yAxes: [{
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ticks: {
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// Include a dollar sign in the ticks
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callback: function(value, index, values) {
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return '$' + value;
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}
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}
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}]
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}
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}
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});
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```
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