docs-v2/content/flux/v0/stdlib/universe/statecount.md

title	description	menu	weight	flux/v0/tags	introduced
stateCount() function	`stateCount()` returns the number of consecutive rows in a given state.	flux_v0_ref name parent identifier stateCount universe universe/stateCount	101	transformations	0.7.0

stateCount() returns the number of consecutive rows in a given state.

The state is defined by the fn predicate function. For each consecutive record that evaluates to true, the state count is incremented. When a record evaluates to false, the value is set to -1 and the state count is reset. If the record generates an error during evaluation, the point is discarded, and does not affect the state count. The state count is added as an additional column to each record.

Function type signature

(<-tables: stream[A], fn: (r: A) => bool, ?column: string) => stream[B] where A: Record, B: Record

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Parameters

fn

({{< req >}}) Predicate function that identifies the state of a record.

column

Column to store the state count in. Default is stateCount.

tables

Input data. Default is piped-forward data (<-).

Examples

Count the number rows in a specific state

import "sampledata"

sampledata.int()
    |> stateCount(fn: (r) => r._value < 10)

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Input data

_time	_value	*tag
2021-01-01T00:00:00Z	-2	t1
2021-01-01T00:00:10Z	10	t1
2021-01-01T00:00:20Z	7	t1
2021-01-01T00:00:30Z	17	t1
2021-01-01T00:00:40Z	15	t1
2021-01-01T00:00:50Z	4	t1

_time	_value	*tag
2021-01-01T00:00:00Z	19	t2
2021-01-01T00:00:10Z	4	t2
2021-01-01T00:00:20Z	-3	t2
2021-01-01T00:00:30Z	19	t2
2021-01-01T00:00:40Z	13	t2
2021-01-01T00:00:50Z	1	t2

Output data

_time	_value	*tag	stateCount
2021-01-01T00:00:00Z	-2	t1	1
2021-01-01T00:00:10Z	10	t1	-1
2021-01-01T00:00:20Z	7	t1	1
2021-01-01T00:00:30Z	17	t1	-1
2021-01-01T00:00:40Z	15	t1	-1
2021-01-01T00:00:50Z	4	t1	1

_time	_value	*tag	stateCount
2021-01-01T00:00:00Z	19	t2	-1
2021-01-01T00:00:10Z	4	t2	1
2021-01-01T00:00:20Z	-3	t2	2
2021-01-01T00:00:30Z	19	t2	-1
2021-01-01T00:00:40Z	13	t2	-1
2021-01-01T00:00:50Z	1	t2	1

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