103 lines
2.7 KiB
Markdown
103 lines
2.7 KiB
Markdown
---
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title: promql.changes() function
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description: >
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`promql.changes()` implements functionality equivalent to
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[PromQL's `changes()` function](https://prometheus.io/docs/prometheus/latest/querying/functions/#changes).
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menu:
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flux_v0_ref:
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name: promql.changes
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parent: internal/promql
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identifier: internal/promql/changes
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weight: 201
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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/internal/promql/promql.flux#L33-L33
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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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`promql.changes()` implements functionality equivalent to
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[PromQL's `changes()` function](https://prometheus.io/docs/prometheus/latest/querying/functions/#changes).
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**Important**: The `internal/promql` package is not meant for external use.
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##### Function type signature
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```js
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(<-tables: stream[{A with _value: float}]) => stream[{B with _value: float}]
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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 number of times that values in a series change
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```js
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import "internal/promql"
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import "sampledata"
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sampledata.float()
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|> promql.changes()
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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 | *tag | _value |
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| -------------------- | ---- | ------- |
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| 2021-01-01T00:00:00Z | t1 | -2.18 |
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| 2021-01-01T00:00:10Z | t1 | 10.92 |
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| 2021-01-01T00:00:20Z | t1 | 7.35 |
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| 2021-01-01T00:00:30Z | t1 | 17.53 |
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| 2021-01-01T00:00:40Z | t1 | 15.23 |
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| 2021-01-01T00:00:50Z | t1 | 4.43 |
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| _time | *tag | _value |
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| -------------------- | ---- | ------- |
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| 2021-01-01T00:00:00Z | t2 | 19.85 |
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| 2021-01-01T00:00:10Z | t2 | 4.97 |
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| 2021-01-01T00:00:20Z | t2 | -3.75 |
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| 2021-01-01T00:00:30Z | t2 | 19.77 |
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| 2021-01-01T00:00:40Z | t2 | 13.86 |
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| 2021-01-01T00:00:50Z | t2 | 1.86 |
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#### Output data
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| *tag | _value |
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| ---- | ------- |
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| t1 | 5 |
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| *tag | _value |
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| ---- | ------- |
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| t2 | 5 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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