84 lines
2.2 KiB
Markdown
84 lines
2.2 KiB
Markdown
---
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title: unique() function
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description: The `unique()` function returns all records containing unique values in a specified column.
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aliases:
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- /influxdb/v2.0/reference/flux/functions/transformations/selectors/unique
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- /influxdb/v2.0/reference/flux/functions/built-in/transformations/selectors/unique/
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- /influxdb/v2.0/reference/flux/stdlib/built-in/transformations/selectors/unique/
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- /influxdb/cloud/reference/flux/stdlib/built-in/transformations/selectors/unique/
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menu:
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flux_0_x_ref:
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name: unique
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parent: universe
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weight: 102
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flux/v0.x/tags: [selectors, transformations]
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introduced: 0.7.0
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---
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The `unique()` function returns all records containing unique values in a specified column.
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Group keys, record columns, and values are **not** modified.
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_`unique()` is a [selector function](/flux/v0.x/function-types/#selectors)._
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```js
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unique(column: "_value")
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```
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{{% warn %}}
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#### Empty tables
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`unique()` drops empty tables.
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{{% /warn %}}
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## Parameters
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### column {data-type="string"}
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Column to search for unique values.
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Defaults to `"_value"`.
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### tables {data-type="stream of tables"}
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Input data.
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Default is piped-forward data ([`<-`](/flux/v0.x/spec/expressions/#pipe-expressions)).
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## Examples
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{{% flux/sample-example-intro %}}
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```js
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import "sampledata"
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sampledata.int()
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|> unique()
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```
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{{< expand-wrapper >}}
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{{% expand "View input and output" %}}
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{{< flex >}}
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{{% flex-content %}}
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##### Input data
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{{% flux/sample "int" %}}
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{{% /flex-content %}}
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{{% flex-content %}}
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##### Output data
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| tag | _time | _value |
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| :-- | :------------------- | -----: |
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| t1 | 2021-01-01T00:00:00Z | -2 |
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| t1 | 2021-01-01T00:00:10Z | 10 |
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| t1 | 2021-01-01T00:00:20Z | 7 |
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| t1 | 2021-01-01T00:00:30Z | 17 |
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| t1 | 2021-01-01T00:00:40Z | 15 |
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| t1 | 2021-01-01T00:00:50Z | 4 |
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| tag | _time | _value |
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| :-- | :------------------- | -----: |
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| t2 | 2021-01-01T00:00:00Z | 19 |
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| t2 | 2021-01-01T00:00:10Z | 4 |
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| t2 | 2021-01-01T00:00:20Z | -3 |
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| t2 | 2021-01-01T00:00:40Z | 13 |
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| t2 | 2021-01-01T00:00:50Z | 1 |
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{{% /flex-content %}}
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{{< /flex >}}
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{{% /expand %}}
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{{< /expand-wrapper >}}
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