106 lines
2.6 KiB
Markdown
106 lines
2.6 KiB
Markdown
---
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title: interpolate.linear() function
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description: >
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`interpolate.linear()` inserts rows at regular intervals using linear interpolation to
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determine values for inserted rows.
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menu:
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flux_v0_ref:
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name: interpolate.linear
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parent: interpolate
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identifier: interpolate/linear
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weight: 101
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flux/v0/tags: [transformations]
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---
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<!------------------------------------------------------------------------------
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IMPORTANT: This page was generated from comments in the Flux source code. Any
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edits made directly to this page will be overwritten the next time the
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documentation is generated.
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To make updates to this documentation, update the function comments above the
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function definition in the Flux source code:
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https://github.com/influxdata/flux/blob/master/stdlib/interpolate/interpolate.flux#L45-L48
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Contributing to Flux: https://github.com/influxdata/flux#contributing
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Fluxdoc syntax: https://github.com/influxdata/flux/blob/master/docs/fluxdoc.md
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------------------------------------------------------------------------------->
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`interpolate.linear()` inserts rows at regular intervals using linear interpolation to
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determine values for inserted rows.
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### Function requirements
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- Input data must have `_time` and `_value` columns.
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- All columns other than `_time` and `_value` must be part of the group key.
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##### Function type signature
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```js
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(<-tables: stream[{A with _value: float, _time: time}], every: duration) => stream[{A with _value: float, _time: time}]
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```
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{{% caption %}}
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For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
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{{% /caption %}}
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## Parameters
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### every
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({{< req >}})
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Duration of time between interpolated points.
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### tables
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Input data. Default is piped-forward data (`<-`).
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## Examples
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### Interpolate missing data by day
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```js
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import "interpolate"
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data
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|> interpolate.linear(every: 1d)
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```
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{{< expand-wrapper >}}
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{{% expand "View example input and output" %}}
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#### Input data
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| _time | _value |
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| -------------------- | ------- |
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| 2021-01-01T00:00:00Z | 10 |
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| 2021-01-02T00:00:00Z | 20 |
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| 2021-01-04T00:00:00Z | 40 |
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| 2021-01-05T00:00:00Z | 50 |
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| 2021-01-08T00:00:00Z | 80 |
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| 2021-01-09T00:00:00Z | 90 |
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#### Output data
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| _time | _value |
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| -------------------- | ------- |
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| 2021-01-01T00:00:00Z | 10 |
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| 2021-01-02T00:00:00Z | 20 |
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| 2021-01-03T00:00:00Z | 30 |
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| 2021-01-04T00:00:00Z | 40 |
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| 2021-01-05T00:00:00Z | 50 |
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| 2021-01-06T00:00:00Z | 60 |
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| 2021-01-07T00:00:00Z | 70 |
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| 2021-01-08T00:00:00Z | 80 |
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| 2021-01-09T00:00:00Z | 90 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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