Chart.js/docs/configuration/decimation.md

# Data Decimation

The decimation plugin can be used with line charts to automatically decimate data at the start of the chart lifecycle. Before enabling this plugin, review the [requirements](#requirements) to ensure that it will work with the chart you want to create.

## Configuration Options

Namespace: `options.plugins.decimation`, the global options for the plugin are defined in `Chart.defaults.plugins.decimation`.

| Name | Type | Default | Description
| ---- | ---- | ------- | -----------
| `enabled` | `boolean` | `true` | Is decimation enabled?
| `algorithm` | `string` | `'min-max'` | Decimation algorithm to use. See the [more...](#decimation-algorithms)
| `samples` | `number` | | If the `'lttb'` algorithm is used, this is the number of samples in the output dataset. Defaults to the canvas width to pick 1 sample per pixel.

## Decimation Algorithms

Decimation algorithm to use for data. Options are:

* `'lttb'`
* `'min-max'`

### Largest Triangle Three Bucket (LTTB) Decimation

[LTTB](https://github.com/sveinn-steinarsson/flot-downsample) decimation reduces the number of data points significantly. This is most useful for showing trends in data using only a few data points.

### Min/Max Decimation

[Min/max](https://digital.ni.com/public.nsf/allkb/F694FFEEA0ACF282862576020075F784) decimation will preserve peaks in your data but could require up to 4 points for each pixel. This type of decimation would work well for a very noisy signal where you need to see data peaks.

## Requirements

To use the decimation plugin, the following requirements must be met:

1. The dataset must have an `indexAxis` of `'x'`
2. The dataset must be a line
3. The X axis for the dataset must be either a `'linear'` or `'time'` type axis
4. The dataset object must be mutable. The plugin stores the original data as `dataset._data` and then defines a new `data` property on the dataset.
Switch docs to Vuepress to match other chart.js repositories (#8751) * Initial work * Update doc commands * Updated sidebar config * Move docs * Update theme version and enable * Convert to chart.js sample * Update scripts to point to local build * Chart.js from local build * Simplify getting-started example * Axis docs updated except for imported content * Common ticks import works * Chart type docs ported to editor plugin * Last pages to use editor * Fix small errors * Frontmatter title to heading * Remove duplicate example * Update sidebar * Add paths * Remove paths * Add getting-started back * Update menus and add copyright to license section of the docs * Add GA plugin * Style sub-groups * Remove unneeded license page since it is covered on the main page * Remove docusaurus readme page * Remove docusaurus files * Fix issues in docs * Build and deploy scripts for docs work * Conditional base URL for nice local testing * Use eslint-plugin-markdown * Remove hard coded lines * Remove mentions of docusaurus Co-authored-by: Jukka Kurkela <jukka.kurkela@gmail.com> 2021-03-30 16:32:39 +02:00			`# Data Decimation`
Create a new hook to enable data decimation (#8255) * Create a new hook to enable data decimation The `beforeElementUpdate` hook can be used to decimate data. The chart elements will not be created until after this hook has fired ensuring that if decimation occurs, only the needed elements will be created. * Address code review feedback * Rename hook to beforeElementsUpdate * Simplify parsing logic * Add decimation plugin to the core * Allow a dataset to specify a different data key * Decimation plugin uses the dataKey feature * Refactor the decimation plugin to support configurable algorithms * Lint the plugin changes * Tests for the dataKey feature * Convert test files to tabs * Standardize on tabs in ts files * Remove the dataKey feature * Replace dataKey usage in decimation plugin We define a new descriptor for the `data` key allowing the plugin to be simpler. * Disable decimation when indexAxis is Y * Simplify the decimation width approximation * Resolve the indexAxis correctly in all cases * Initial documentation * Reverse check * Update TS definitions for new plugin options * Move defineProperty after bailouts * Add destroy hook 2021-02-01 22:37:32 +01:00
			`The decimation plugin can be used with line charts to automatically decimate data at the start of the chart lifecycle. Before enabling this plugin, review the [requirements](#requirements) to ensure that it will work with the chart you want to create.`

			`## Configuration Options`

Clarify options placement (#8427) * improve clarity of docs by showing party qualified names in table and place of the namespace above * add missing line * remove partial qualified names, made some tables unusable and made it overall bit unclear. Added the namespace above each table * fix sidebars tabs to spaces * implement kurkles feedback 2021-02-19 17:44:05 +01:00			Namespace: `options.plugins.decimation`, the global options for the plugin are defined in `Chart.defaults.plugins.decimation`.
Create a new hook to enable data decimation (#8255) * Create a new hook to enable data decimation The `beforeElementUpdate` hook can be used to decimate data. The chart elements will not be created until after this hook has fired ensuring that if decimation occurs, only the needed elements will be created. * Address code review feedback * Rename hook to beforeElementsUpdate * Simplify parsing logic * Add decimation plugin to the core * Allow a dataset to specify a different data key * Decimation plugin uses the dataKey feature * Refactor the decimation plugin to support configurable algorithms * Lint the plugin changes * Tests for the dataKey feature * Convert test files to tabs * Standardize on tabs in ts files * Remove the dataKey feature * Replace dataKey usage in decimation plugin We define a new descriptor for the `data` key allowing the plugin to be simpler. * Disable decimation when indexAxis is Y * Simplify the decimation width approximation * Resolve the indexAxis correctly in all cases * Initial documentation * Reverse check * Update TS definitions for new plugin options * Move defineProperty after bailouts * Add destroy hook 2021-02-01 22:37:32 +01:00
			`\| Name \| Type \| Default \| Description`
			`\| ---- \| ---- \| ------- \| -----------`
			\| `enabled` \| `boolean` \| `true` \| Is decimation enabled?
			\| `algorithm` \| `string` \| `'min-max'` \| Decimation algorithm to use. See the [more...](#decimation-algorithms)
LTTB Decimation (#8468) * LTTB Decimation * Lint fixes 2021-02-21 15:15:45 +01:00			\| `samples` \| `number` \| \| If the `'lttb'` algorithm is used, this is the number of samples in the output dataset. Defaults to the canvas width to pick 1 sample per pixel.
Create a new hook to enable data decimation (#8255) * Create a new hook to enable data decimation The `beforeElementUpdate` hook can be used to decimate data. The chart elements will not be created until after this hook has fired ensuring that if decimation occurs, only the needed elements will be created. * Address code review feedback * Rename hook to beforeElementsUpdate * Simplify parsing logic * Add decimation plugin to the core * Allow a dataset to specify a different data key * Decimation plugin uses the dataKey feature * Refactor the decimation plugin to support configurable algorithms * Lint the plugin changes * Tests for the dataKey feature * Convert test files to tabs * Standardize on tabs in ts files * Remove the dataKey feature * Replace dataKey usage in decimation plugin We define a new descriptor for the `data` key allowing the plugin to be simpler. * Disable decimation when indexAxis is Y * Simplify the decimation width approximation * Resolve the indexAxis correctly in all cases * Initial documentation * Reverse check * Update TS definitions for new plugin options * Move defineProperty after bailouts * Add destroy hook 2021-02-01 22:37:32 +01:00
			`## Decimation Algorithms`

			`Decimation algorithm to use for data. Options are:`

LTTB Decimation (#8468) * LTTB Decimation * Lint fixes 2021-02-21 15:15:45 +01:00			* `'lttb'`
Create a new hook to enable data decimation (#8255) * Create a new hook to enable data decimation The `beforeElementUpdate` hook can be used to decimate data. The chart elements will not be created until after this hook has fired ensuring that if decimation occurs, only the needed elements will be created. * Address code review feedback * Rename hook to beforeElementsUpdate * Simplify parsing logic * Add decimation plugin to the core * Allow a dataset to specify a different data key * Decimation plugin uses the dataKey feature * Refactor the decimation plugin to support configurable algorithms * Lint the plugin changes * Tests for the dataKey feature * Convert test files to tabs * Standardize on tabs in ts files * Remove the dataKey feature * Replace dataKey usage in decimation plugin We define a new descriptor for the `data` key allowing the plugin to be simpler. * Disable decimation when indexAxis is Y * Simplify the decimation width approximation * Resolve the indexAxis correctly in all cases * Initial documentation * Reverse check * Update TS definitions for new plugin options * Move defineProperty after bailouts * Add destroy hook 2021-02-01 22:37:32 +01:00			* `'min-max'`

LTTB Decimation (#8468) * LTTB Decimation * Lint fixes 2021-02-21 15:15:45 +01:00			`### Largest Triangle Three Bucket (LTTB) Decimation`

			`[LTTB](https://github.com/sveinn-steinarsson/flot-downsample) decimation reduces the number of data points significantly. This is most useful for showing trends in data using only a few data points.`

Create a new hook to enable data decimation (#8255) * Create a new hook to enable data decimation The `beforeElementUpdate` hook can be used to decimate data. The chart elements will not be created until after this hook has fired ensuring that if decimation occurs, only the needed elements will be created. * Address code review feedback * Rename hook to beforeElementsUpdate * Simplify parsing logic * Add decimation plugin to the core * Allow a dataset to specify a different data key * Decimation plugin uses the dataKey feature * Refactor the decimation plugin to support configurable algorithms * Lint the plugin changes * Tests for the dataKey feature * Convert test files to tabs * Standardize on tabs in ts files * Remove the dataKey feature * Replace dataKey usage in decimation plugin We define a new descriptor for the `data` key allowing the plugin to be simpler. * Disable decimation when indexAxis is Y * Simplify the decimation width approximation * Resolve the indexAxis correctly in all cases * Initial documentation * Reverse check * Update TS definitions for new plugin options * Move defineProperty after bailouts * Add destroy hook 2021-02-01 22:37:32 +01:00			`### Min/Max Decimation`

			`[Min/max](https://digital.ni.com/public.nsf/allkb/F694FFEEA0ACF282862576020075F784) decimation will preserve peaks in your data but could require up to 4 points for each pixel. This type of decimation would work well for a very noisy signal where you need to see data peaks.`

			`## Requirements`

			`To use the decimation plugin, the following requirements must be met:`

			1. The dataset must have an `indexAxis` of `'x'`
			`2. The dataset must be a line`
			3. The X axis for the dataset must be either a `'linear'` or `'time'` type axis
			4. The dataset object must be mutable. The plugin stores the original data as `dataset._data` and then defines a new `data` property on the dataset.