161 lines
4.4 KiB
Markdown
161 lines
4.4 KiB
Markdown
---
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title: stateDuration() function
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description: >
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`stateDuration()` returns the cumulative duration of a given state.
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menu:
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flux_v0_ref:
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name: stateDuration
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parent: universe
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identifier: universe/stateDuration
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weight: 101
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flux/v0/tags: [transformations]
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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#L4077-L4085
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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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`stateDuration()` returns the cumulative duration of a given state.
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The state is defined by the `fn` predicate function. For each consecutive
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record that evaluates to `true`, the state duration is incremented by the
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duration of time between records using the specified `unit`. When a record
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evaluates to `false`, the value is set to `-1` and the state duration is reset.
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If the record generates an error during evaluation, the point is discarded,
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and does not affect the state duration.
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The state duration is added as an additional column to each record.
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The duration is represented as an integer in the units specified.
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**Note:** As the first point in the given state has no previous point, its
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state duration will be 0.
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##### Function type signature
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```js
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(
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<-tables: stream[A],
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fn: (r: A) => bool,
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?column: string,
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?timeColumn: string,
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?unit: duration,
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) => 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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### fn
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({{< req >}})
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Predicate function that identifies the state of a record.
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### column
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Column to store the state duration in. Default is `stateDuration`.
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### timeColumn
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Time column to use to calculate elapsed time between rows.
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Default is `_time`.
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### unit
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Unit of time to use to increment state duration. Default is `1s` (seconds).
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**Example units:**
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- 1ns (nanoseconds)
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- 1us (microseconds)
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- 1ms (milliseconds)
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- 1s (seconds)
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- 1m (minutes)
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- 1h (hours)
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- 1d (days)
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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 time spent in a specified state
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```js
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import "sampledata"
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sampledata.int()
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|> stateDuration(fn: (r) => r._value < 15)
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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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| _time | _value | *tag | stateDuration |
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| -------------------- | ------- | ---- | -------------- |
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| 2021-01-01T00:00:00Z | -2 | t1 | 0 |
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| 2021-01-01T00:00:10Z | 10 | t1 | 10 |
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| 2021-01-01T00:00:20Z | 7 | t1 | 20 |
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| 2021-01-01T00:00:30Z | 17 | t1 | -1 |
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| 2021-01-01T00:00:40Z | 15 | t1 | -1 |
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| 2021-01-01T00:00:50Z | 4 | t1 | 0 |
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| _time | _value | *tag | stateDuration |
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| -------------------- | ------- | ---- | -------------- |
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| 2021-01-01T00:00:00Z | 19 | t2 | -1 |
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| 2021-01-01T00:00:10Z | 4 | t2 | 0 |
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| 2021-01-01T00:00:20Z | -3 | t2 | 10 |
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| 2021-01-01T00:00:30Z | 19 | t2 | -1 |
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| 2021-01-01T00:00:40Z | 13 | t2 | 0 |
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| 2021-01-01T00:00:50Z | 1 | t2 | 10 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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