140 lines
3.7 KiB
Markdown
140 lines
3.7 KiB
Markdown
---
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title: truncateTimeColumn() function
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description: >
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`truncateTimeColumn()` truncates all input time values in the `_time` to a
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specified unit.
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menu:
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flux_v0_ref:
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name: truncateTimeColumn
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parent: universe
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identifier: universe/truncateTimeColumn
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weight: 101
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flux/v0/tags: [transformations, date/time]
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introduced: 0.37.0
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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#L4595-L4597
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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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`truncateTimeColumn()` truncates all input time values in the `_time` to a
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specified unit.
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#### Truncate to weeks
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When truncating a time value to the week (`1w`), weeks are determined using the
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**Unix epoch (1970-01-01T00:00:00Z UTC)**. The Unix epoch was on a Thursday,
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so all calculated weeks begin on Thursday.
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##### Function type signature
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```js
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(<-tables: stream[{B with _time: C}], unit: duration, ?timeColumn: A) => stream[{B with _time: C, _time: time}] where C: Timeable
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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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### unit
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({{< req >}})
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Unit of time to truncate to.
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**Example units:**
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- 1ns (nanosecond)
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- 1us (microsecond)
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- 1ms (millisecond)
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- 1s (second)
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- 1m (minute)
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- 1h (hour)
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- 1d (day)
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- 1w (week)
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- 1mo (month)
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- 1y (year)
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### timeColumn
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Time column to truncate. Default is `_time`.
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**Note:** Currently, assigning a custom value to this parameter will have
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no effect.
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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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### Truncate all time values to the minute
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```js
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import "sampledata"
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sampledata.int()
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|> truncateTimeColumn(unit: 1m)
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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 |
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| -------------------- | ------- | ---- |
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| 2021-01-01T00:00:00Z | -2 | t1 |
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| 2021-01-01T00:00:00Z | 10 | t1 |
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| 2021-01-01T00:00:00Z | 7 | t1 |
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| 2021-01-01T00:00:00Z | 17 | t1 |
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| 2021-01-01T00:00:00Z | 15 | t1 |
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| 2021-01-01T00:00:00Z | 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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| 2021-01-01T00:00:00Z | 4 | t2 |
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| 2021-01-01T00:00:00Z | -3 | t2 |
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| 2021-01-01T00:00:00Z | 19 | t2 |
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| 2021-01-01T00:00:00Z | 13 | t2 |
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| 2021-01-01T00:00:00Z | 1 | t2 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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