docs-v2/content/flux/v0/stdlib/experimental/stddev.md

title	description	menu	weight	flux/v0/tags	introduced
experimental.stddev() function	`experimental.stddev()` returns the standard deviation of non-null values in the `_value` column for each input table.	flux_v0_ref name parent identifier experimental.stddev experimental experimental/stddev	101	transformations aggregates	0.107.0

experimental.stddev() returns the standard deviation of non-null values in the _value column for each input table.

Standard deviation modes

The following modes are available when calculating the standard deviation of data.

sample

Calculate the sample standard deviation where the data is considered to be part of a larger population.

population

Calculate the population standard deviation where the data is considered a population of its own.

Function type signature

(<-tables: stream[{A with _value: float}], ?mode: string) => stream[{A with _value: float}]

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Parameters

mode

Standard deviation mode or type of standard deviation to calculate. Default is sample.

Available options:

• sample
• population

tables

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

Examples

Return the standard deviation in input tables

import "experimental"
import "sampledata"

sampledata.float()
    |> experimental.stddev()

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Input data

_time	*tag	_value
2021-01-01T00:00:00Z	t1	-2.18
2021-01-01T00:00:10Z	t1	10.92
2021-01-01T00:00:20Z	t1	7.35
2021-01-01T00:00:30Z	t1	17.53
2021-01-01T00:00:40Z	t1	15.23
2021-01-01T00:00:50Z	t1	4.43

_time	*tag	_value
2021-01-01T00:00:00Z	t2	19.85
2021-01-01T00:00:10Z	t2	4.97
2021-01-01T00:00:20Z	t2	-3.75
2021-01-01T00:00:30Z	t2	19.77
2021-01-01T00:00:40Z	t2	13.86
2021-01-01T00:00:50Z	t2	1.86

Output data

*tag	_value
t1	7.263244454099008

*tag	_value
t2	9.85926704510364

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