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

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`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

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

{{% caption %}}
For more information, see [Function type signatures](/flux/v0/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)
- [Calculate a three point moving average with null values](#calculate-a-three-point-moving-average-with-null-values)

### Calculate a three point moving average

```js
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

```js
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 >}}