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

title	description	menu	weight	flux/v0/tags	introduced
movingAverage() function	`movingAverage()` calculates the mean of non-null values using the current value and `n - 1` previous values in the `_values` column.	flux_v0_ref name parent identifier movingAverage universe universe/movingAverage	101	transformations	0.35.0

movingAverage() calculates the mean of non-null values using the current value and n - 1 previous values in the _values column.

Moving average rules

• The average over a period populated by n values is equal to their algebraic mean.
• The average over a period populated by only null values is null.
• Moving averages skip null values.
• If n is less than the number of records in a table, movingAverage() returns the average of the available values.

Function type signature

(<-tables: stream[{A with _value: B}], n: int) => stream[{A with _value: float}] where B: Numeric

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

Parameters

n

({{< req >}}) Number of values to average.

tables

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

Examples

• Calculate a three point moving average
• Calculate a three point moving average with null values

Calculate a three point moving average

import "sampledata"

sampledata.int()
    |> movingAverage(n: 3)

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

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
2021-01-01T00:00:20Z	5	t1
2021-01-01T00:00:30Z	11.333333333333334	t1
2021-01-01T00:00:40Z	13	t1
2021-01-01T00:00:50Z	12	t1

_time	_value	*tag
2021-01-01T00:00:20Z	6.666666666666667	t2
2021-01-01T00:00:30Z	6.666666666666667	t2
2021-01-01T00:00:40Z	9.666666666666666	t2
2021-01-01T00:00:50Z	11	t2

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

Calculate a three point moving average with null values

import "sampledata"

sampledata.int(includeNull: true)
    |> movingAverage(n: 3)

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

Input data

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

_time	_value	*tag
2021-01-01T00:00:00Z		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		t2
2021-01-01T00:00:50Z	1	t2

Output data

_time	_value	*tag
2021-01-01T00:00:20Z	2.5	t1
2021-01-01T00:00:30Z	7	t1
2021-01-01T00:00:40Z	7	t1
2021-01-01T00:00:50Z	4	t1

_time	_value	*tag
2021-01-01T00:00:20Z	0.5	t2
2021-01-01T00:00:30Z	6.666666666666667	t2
2021-01-01T00:00:40Z	8	t2
2021-01-01T00:00:50Z	10	t2

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