docs-v2/content/flux/v0/stdlib/regexp/findstring.md

title	description	menu	weight
regexp.findString() function	`regexp.findString()` returns the left-most regular expression match in a string.	flux_v0_ref name parent identifier regexp.findString regexp regexp/findString	101

regexp.findString() returns the left-most regular expression match in a string.

Function type signature

(r: regexp, v: string) => string

{{% caption %}} For more information, see Function type signatures. {{% /caption %}}

Parameters

r

({{< req >}}) Regular expression used to search v.

v

({{< req >}}) String value to search.

Examples

• Return the first regular expression match in a string
• Find the first regular expression match in each row

Return the first regular expression match in a string

import "regexp"

regexp.findString(r: /foo.?/, v: "seafood fool")// Returns "food"

Find the first regular expression match in each row

import "regexp"
import "sampledata"

regex = /.{6}$/

sampledata.string()
    |> map(fn: (r) => ({r with _value: regexp.findString(v: r._value, r: regex)}))

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Input data

_time	*tag	_value
2021-01-01T00:00:00Z	t1	smpl_g9qczs
2021-01-01T00:00:10Z	t1	smpl_0mgv9n
2021-01-01T00:00:20Z	t1	smpl_phw664
2021-01-01T00:00:30Z	t1	smpl_guvzy4
2021-01-01T00:00:40Z	t1	smpl_5v3cce
2021-01-01T00:00:50Z	t1	smpl_s9fmgy

_time	*tag	_value
2021-01-01T00:00:00Z	t2	smpl_b5eida
2021-01-01T00:00:10Z	t2	smpl_eu4oxp
2021-01-01T00:00:20Z	t2	smpl_5g7tz4
2021-01-01T00:00:30Z	t2	smpl_sox1ut
2021-01-01T00:00:40Z	t2	smpl_wfm757
2021-01-01T00:00:50Z	t2	smpl_dtn2bv

Output data

_time	_value	*tag
2021-01-01T00:00:00Z	g9qczs	t1
2021-01-01T00:00:10Z	0mgv9n	t1
2021-01-01T00:00:20Z	phw664	t1
2021-01-01T00:00:30Z	guvzy4	t1
2021-01-01T00:00:40Z	5v3cce	t1
2021-01-01T00:00:50Z	s9fmgy	t1

_time	_value	*tag
2021-01-01T00:00:00Z	b5eida	t2
2021-01-01T00:00:10Z	eu4oxp	t2
2021-01-01T00:00:20Z	5g7tz4	t2
2021-01-01T00:00:30Z	sox1ut	t2
2021-01-01T00:00:40Z	wfm757	t2
2021-01-01T00:00:50Z	dtn2bv	t2

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