156 lines
5.4 KiB
Markdown
156 lines
5.4 KiB
Markdown
# Time Cartesian Axis
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The time scale is used to display times and dates. When building its ticks, it will automatically calculate the most comfortable unit base on the size of the scale.
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## Data Sets
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### Input Data
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The x-axis data points may additionally be specified via the `t` or `x` attribute when using the time scale.
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```javascript
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data: [{
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x: new Date(),
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y: 1
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}, {
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t: new Date(),
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y: 10
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}]
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```
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### Date Formats
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When providing data for the time scale, Chart.js supports all of the formats that Moment.js accepts. See [Moment.js docs](https://momentjs.com/docs/#/parsing/) for details.
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## Configuration Options
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The following options are provided by the time scale. You may also set options provided by the [common tick configuration](README.md#tick-configuration).
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| Name | Type | Default | Description
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| ---- | ---- | ------- | -----------
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| `adapters.date` | `object` | `{}` | Options for adapter for external date library if that adapter needs or supports options
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| `distribution` | `string` | `'linear'` | How data is plotted. [more...](#scale-distribution)
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| `bounds` | `string` | `'data'` | Determines the scale bounds. [more...](#scale-bounds)
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| `ticks.source` | `string` | `'auto'` | How ticks are generated. [more...](#ticks-source)
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| `time.displayFormats` | `object` | | Sets how different time units are displayed. [more...](#display-formats)
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| `time.isoWeekday` | `boolean` | `false` | If true and the unit is set to 'week', then the first day of the week will be Monday. Otherwise, it will be Sunday.
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| `time.max` | [Time](#date-formats) | | If defined, this will override the data maximum.
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| `time.min` | [Time](#date-formats) | | If defined, this will override the data minimum.
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| `time.parser` | <code>string|function</code> | | Custom parser for dates. [more...](#parser)
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| `time.round` | `string` | `false` | If defined, dates will be rounded to the start of this unit. See [Time Units](#time-units) below for the allowed units.
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| `time.tooltipFormat` | `string` | | The Moment.js format string to use for the tooltip.
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| `time.unit` | `string` | `false` | If defined, will force the unit to be a certain type. See [Time Units](#time-units) section below for details.
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| `time.stepSize` | `number` | `1` | The number of units between grid lines.
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| `time.minUnit` | `string` | `'millisecond'` | The minimum display format to be used for a time unit.
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### Time Units
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The following time measurements are supported. The names can be passed as strings to the `time.unit` config option to force a certain unit.
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* `'millisecond'`
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* `'second'`
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* `'minute'`
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* `'hour'`
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* `'day'`
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* `'week'`
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* `'month'`
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* `'quarter'`
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* `'year'`
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For example, to create a chart with a time scale that always displayed units per month, the following config could be used.
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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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xAxes: [{
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type: 'time',
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time: {
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unit: 'month'
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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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### Display Formats
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The following display formats are used to configure how different time units are formed into strings for the axis tick marks. See [Moment.js](https://momentjs.com/docs/#/displaying/format/) for the allowable format strings.
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Name | Default | Example
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--- | --- | ---
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`millisecond` | `'h:mm:ss.SSS a'` | `'11:20:01.123 AM'`
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`second` | `'h:mm:ss a'` | `'11:20:01 AM'`
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`minute` | `'h:mm a'` | `'11:20 AM'`
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`hour` | `'hA'` | `'11AM'`
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`day` | `'MMM D'` | `'Sep 4'`
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`week` | `'ll'` | `'Sep 4 2015'`
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`month` | `'MMM YYYY'` | `'Sep 2015'`
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`quarter` | `'[Q]Q - YYYY'` | `'Q3 - 2015'`
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`year` | `'YYYY'` | `'2015'`
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For example, to set the display format for the `quarter` unit to show the month and year, the following config would be passed to the chart constructor.
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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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xAxes: [{
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type: 'time',
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time: {
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displayFormats: {
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quarter: 'MMM YYYY'
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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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### Scale Distribution
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The `distribution` property controls the data distribution along the scale:
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* `'linear'`: data are spread according to their time (distances can vary)
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* `'series'`: data are spread at the same distance from each other
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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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xAxes: [{
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type: 'time',
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distribution: 'series'
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}]
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}
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}
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});
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```
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### Scale Bounds
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The `bounds` property controls the scale boundary strategy (bypassed by `min`/`max` time options).
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* `'data'`: makes sure data are fully visible, labels outside are removed
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* `'ticks'`: makes sure ticks are fully visible, data outside are truncated
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### Ticks Source
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The `ticks.source` property controls the ticks generation.
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* `'auto'`: generates "optimal" ticks based on scale size and time options
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* `'data'`: generates ticks from data (including labels from data `{t|x|y}` objects)
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* `'labels'`: generates ticks from user given `data.labels` values ONLY
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### Parser
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If this property is defined as a string, it is interpreted as a custom format to be used by Moment.js to parse the date.
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If this is a function, it must return a Moment.js object given the appropriate data value.
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