133 lines
3.5 KiB
Markdown
133 lines
3.5 KiB
Markdown
---
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title: regexp.findString() function
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description: >
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`regexp.findString()` returns the left-most regular expression match in a string.
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menu:
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flux_v0_ref:
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name: regexp.findString
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parent: regexp
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identifier: regexp/findString
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weight: 101
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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/regexp/regexp.flux#L74-L74
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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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`regexp.findString()` returns the left-most regular expression match in a string.
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##### Function type signature
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```js
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(r: regexp, v: string) => string
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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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### r
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({{< req >}})
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Regular expression used to search `v`.
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### v
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({{< req >}})
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String value to search.
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## Examples
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- [Return the first regular expression match in a string](#return-the-first-regular-expression-match-in-a-string)
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- [Find the first regular expression match in each row](#find-the-first-regular-expression-match-in-each-row)
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### Return the first regular expression match in a string
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```js
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import "regexp"
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regexp.findString(r: /foo.?/, v: "seafood fool")// Returns "food"
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```
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### Find the first regular expression match in each row
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```js
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import "regexp"
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import "sampledata"
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regex = /.{6}$/
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sampledata.string()
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|> map(fn: (r) => ({r with _value: regexp.findString(v: r._value, r: regex)}))
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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 | smpl_g9qczs |
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| 2021-01-01T00:00:10Z | t1 | smpl_0mgv9n |
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| 2021-01-01T00:00:20Z | t1 | smpl_phw664 |
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| 2021-01-01T00:00:30Z | t1 | smpl_guvzy4 |
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| 2021-01-01T00:00:40Z | t1 | smpl_5v3cce |
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| 2021-01-01T00:00:50Z | t1 | smpl_s9fmgy |
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| _time | *tag | _value |
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| -------------------- | ---- | ----------- |
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| 2021-01-01T00:00:00Z | t2 | smpl_b5eida |
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| 2021-01-01T00:00:10Z | t2 | smpl_eu4oxp |
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| 2021-01-01T00:00:20Z | t2 | smpl_5g7tz4 |
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| 2021-01-01T00:00:30Z | t2 | smpl_sox1ut |
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| 2021-01-01T00:00:40Z | t2 | smpl_wfm757 |
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| 2021-01-01T00:00:50Z | t2 | smpl_dtn2bv |
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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 | g9qczs | t1 |
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| 2021-01-01T00:00:10Z | 0mgv9n | t1 |
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| 2021-01-01T00:00:20Z | phw664 | t1 |
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| 2021-01-01T00:00:30Z | guvzy4 | t1 |
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| 2021-01-01T00:00:40Z | 5v3cce | t1 |
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| 2021-01-01T00:00:50Z | s9fmgy | t1 |
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| _time | _value | *tag |
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| -------------------- | ------- | ---- |
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| 2021-01-01T00:00:00Z | b5eida | t2 |
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| 2021-01-01T00:00:10Z | eu4oxp | t2 |
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| 2021-01-01T00:00:20Z | 5g7tz4 | t2 |
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| 2021-01-01T00:00:30Z | sox1ut | t2 |
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| 2021-01-01T00:00:40Z | wfm757 | t2 |
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| 2021-01-01T00:00:50Z | dtn2bv | t2 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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