119 lines
3.2 KiB
Markdown
119 lines
3.2 KiB
Markdown
---
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title: strings.lastIndex() function
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description: >
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`strings.lastIndex()` returns the index of the last instance of a substring in a string.
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If the substring is not present, the function returns -1.
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menu:
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flux_v0_ref:
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name: strings.lastIndex
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parent: strings
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identifier: strings/lastIndex
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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/strings/strings.flux#L472-L472
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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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`strings.lastIndex()` returns the index of the last instance of a substring in a string.
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If the substring is not present, the function returns -1.
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##### Function type signature
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```js
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(substr: string, v: string) => int
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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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### v
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({{< req >}})
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String value to search.
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### substr
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({{< req >}})
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Substring to search for.
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## Examples
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### Find the index of the last occurrence of a substring
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```js
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import "sampledata"
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import "strings"
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sampledata.string()
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|> map(fn: (r) => ({r with _value: strings.lastIndex(v: r._value, substr: "g")}))
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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 | 5 | t1 |
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| 2021-01-01T00:00:10Z | 7 | t1 |
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| 2021-01-01T00:00:20Z | -1 | t1 |
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| 2021-01-01T00:00:30Z | 5 | t1 |
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| 2021-01-01T00:00:40Z | -1 | t1 |
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| 2021-01-01T00:00:50Z | 9 | t1 |
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| _time | _value | *tag |
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| -------------------- | ------- | ---- |
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| 2021-01-01T00:00:00Z | -1 | t2 |
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| 2021-01-01T00:00:10Z | -1 | t2 |
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| 2021-01-01T00:00:20Z | 6 | t2 |
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| 2021-01-01T00:00:30Z | -1 | t2 |
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| 2021-01-01T00:00:40Z | -1 | t2 |
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| 2021-01-01T00:00:50Z | -1 | t2 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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