223 lines
5.3 KiB
Markdown
223 lines
5.3 KiB
Markdown
---
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title: distinct() function
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description: >
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`distinct()` returns all unique values in a specified column.
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menu:
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flux_v0_ref:
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name: distinct
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parent: universe
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identifier: universe/distinct
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weight: 101
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flux/v0/tags: [transformations, selectors]
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introduced: 0.7.0
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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/universe/universe.flux#L425-L425
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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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`distinct()` returns all unique values in a specified column.
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The `_value` of each output record is set to a distinct value in the specified column.
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`null` is considered its own distinct value if present.
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##### Function type signature
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```js
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(<-tables: stream[A], ?column: string) => stream[B] where A: Record, B: Record
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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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### column
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Column to return unique values from. Default is `_value`.
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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 distinct values from the _value column](#return-distinct-values-from-the-_value-column)
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- [Return distinct values from a non-default column](#return-distinct-values-from-a-non-default-column)
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- [Return distinct values from data with null values](#return-distinct-values-from-data-with-null-values)
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### Return distinct values from the _value column
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```js
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import "sampledata"
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sampledata.int()
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|> distinct()
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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 | 10 | t1 |
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| 2021-01-01T00:00:20Z | 7 | t1 |
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| 2021-01-01T00:00:30Z | 17 | t1 |
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| 2021-01-01T00:00:40Z | 15 | 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 | 19 | 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 | 13 | t2 |
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| 2021-01-01T00:00:50Z | 1 | t2 |
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#### Output data
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| *tag | _value |
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| ---- | ------- |
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| t1 | -2 |
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| t1 | 10 |
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| t1 | 7 |
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| t1 | 17 |
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| t1 | 15 |
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| t1 | 4 |
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| *tag | _value |
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| ---- | ------- |
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| t2 | 19 |
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| t2 | 4 |
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| t2 | -3 |
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| t2 | 13 |
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| t2 | 1 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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### Return distinct values from a non-default column
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```js
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import "sampledata"
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sampledata.int()
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|> distinct(column: "tag")
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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 | 10 | t1 |
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| 2021-01-01T00:00:20Z | 7 | t1 |
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| 2021-01-01T00:00:30Z | 17 | t1 |
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| 2021-01-01T00:00:40Z | 15 | 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 | 19 | 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 | 13 | t2 |
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| 2021-01-01T00:00:50Z | 1 | t2 |
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#### Output data
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| *tag | _value |
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| ---- | ------- |
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| t1 | t1 |
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| *tag | _value |
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| ---- | ------- |
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| t2 | t2 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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### Return distinct values from data with null values
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```js
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import "sampledata"
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sampledata.int(includeNull: true)
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|> distinct()
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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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| *tag | _value |
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| ---- | ------- |
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| t1 | -2 |
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| t1 | |
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| t1 | 7 |
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| t1 | 4 |
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| *tag | _value |
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| ---- | ------- |
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| t2 | |
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| t2 | 4 |
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| t2 | -3 |
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| t2 | 19 |
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| t2 | 1 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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