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44 lines
2.4 KiB
Markdown
44 lines
2.4 KiB
Markdown
# Data Decimation
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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.
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## Configuration Options
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Namespace: `options.plugins.decimation`, the global options for the plugin are defined in `Chart.defaults.plugins.decimation`.
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| Name | Type | Default | Description
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| ---- | ---- | ------- | -----------
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| `enabled` | `boolean` | `false` | Is decimation enabled?
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| `algorithm` | `string` | `'min-max'` | Decimation algorithm to use. See the [more...](#decimation-algorithms)
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| `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.
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| `threshold` | `number` | | If the number of samples in the current axis range is above this value, the decimation will be triggered. Defaults to 4 times the canvas width.<br />The number of point after decimation can be higher than the `threshold` value.
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## Decimation Algorithms
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Decimation algorithm to use for data. Options are:
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* `'lttb'`
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* `'min-max'`
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### Largest Triangle Three Bucket (LTTB) Decimation
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[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.
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### Min/Max Decimation
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[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.
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## Requirements
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To use the decimation plugin, the following requirements must be met:
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1. The dataset must have an [`indexAxis`](../charts/line.md#general) of `'x'`
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2. The dataset must be a line
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3. The X axis for the dataset must be either a [`'linear'`](../axes/cartesian/linear.md) or [`'time'`](../axes/cartesian/time.md) type axis
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4. Data must not need parsing, i.e. [`parsing`](../general/data-structures.md#dataset-configuration) must be `false`
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5. 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.
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## Related Samples
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* [Data Decimation Sample](../samples/advanced/data-decimation)
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