105 lines
2.8 KiB
Markdown
105 lines
2.8 KiB
Markdown
---
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title: experimental.first() function
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description: >
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`experimental.first()` returns the first record with a non-null value in the `_value` column
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for each input table.
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menu:
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flux_v0_ref:
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name: experimental.first
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parent: experimental
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identifier: experimental/first
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weight: 101
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flux/v0/tags: [transformations, selectors]
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introduced: 0.112.0
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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/experimental/experimental.flux#L1119-L1119
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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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`experimental.first()` returns the first record with a non-null value in the `_value` column
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for each input table.
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`experimental.first()` drops empty tables.
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##### Function type signature
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```js
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(<-tables: stream[{A with _value: B}]) => stream[{A with _value: B}]
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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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### tables
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Input data. Default is piped-forward data (`<-`).
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## Examples
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### Return the first non-null value in each input table
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```js
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import "experimental"
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import "sampledata"
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sampledata.int(includeNull: true)
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|> experimental.first()
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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 | *tag |
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| -------------------- | ------- | ---- |
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| 2021-01-01T00:00:00Z | -2 | t1 |
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| 2021-01-01T00:00:10Z | | t1 |
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| 2021-01-01T00:00:20Z | 7 | t1 |
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| 2021-01-01T00:00:30Z | | t1 |
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| 2021-01-01T00:00:40Z | | t1 |
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| 2021-01-01T00:00:50Z | 4 | t1 |
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| _time | _value | *tag |
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| -------------------- | ------- | ---- |
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| 2021-01-01T00:00:00Z | | t2 |
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| 2021-01-01T00:00:10Z | 4 | t2 |
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| 2021-01-01T00:00:20Z | -3 | t2 |
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| 2021-01-01T00:00:30Z | 19 | t2 |
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| 2021-01-01T00:00:40Z | | t2 |
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| 2021-01-01T00:00:50Z | 1 | t2 |
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#### Output data
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| _time | _value | *tag |
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| -------------------- | ------- | ---- |
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| 2021-01-01T00:00:00Z | -2 | t1 |
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| _time | _value | *tag |
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| -------------------- | ------- | ---- |
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| 2021-01-01T00:00:10Z | 4 | t2 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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