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stddev() function

content/flux/v0/stdlib/universe/stddev.md

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stddev() returns the standard deviation of non-null values in a specified column.

Function type signature
js
(<-tables: stream[A], ?column: string, ?mode: string) => stream[B] where A: Record, B: Record

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

Parameters

column

Column to operate on. Default is _value.

mode

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

Available modes:

  • sample: Calculate the sample standard deviation where the data is considered part of a larger population.
  • population: Calculate the population standard deviation where the data is considered a population of its own.

tables

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

Examples

Return the standard deviation of values in each table

js
import "sampledata"

sampledata.int()
    |> stddev()

{{< expand-wrapper >}} {{% expand "View example input and output" %}}

Input data

_time_value*tag
2021-01-01T00:00:00Z-2t1
2021-01-01T00:00:10Z10t1
2021-01-01T00:00:20Z7t1
2021-01-01T00:00:30Z17t1
2021-01-01T00:00:40Z15t1
2021-01-01T00:00:50Z4t1
_time_value*tag
2021-01-01T00:00:00Z19t2
2021-01-01T00:00:10Z4t2
2021-01-01T00:00:20Z-3t2
2021-01-01T00:00:30Z19t2
2021-01-01T00:00:40Z13t2
2021-01-01T00:00:50Z1t2

Output data

*tag_value
t17.063993204979744
*tag_value
t29.474527252938094

{{% /expand %}} {{< /expand-wrapper >}}