---
title: aggregate.rate() function
description: >
  `aggregate.rate()` calculates the average rate of increase per window of time for each
  input table.
menu:
  flux_v0_ref:
    name: aggregate.rate
    parent: experimental/aggregate
    identifier: experimental/aggregate/rate
weight: 201
flux/v0/tags: [transformations, aggregates]
---

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`aggregate.rate()` calculates the average rate of increase per window of time for each
input table.

`aggregate.rate()` requires that input data have `_start` and `_stop` columns
to calculate windows of time to operate on.
Use `range()` to assign `_start` and `_stop` values.

This function is designed to replicate the
[Prometheus `rate()` function](https://prometheus.io/docs/prometheus/latest/querying/functions/#rate)
and should only be used with [counters](/flux/v0/prometheus/metric-types/counter/).

##### Function type signature

```js
(<-tables: stream[A], every: duration, ?groupColumns: [string], ?unit: duration) => stream[B] where A: Record, B: Record
```

{{% caption %}}
For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
{{% /caption %}}

## Parameters

### every
({{< req >}})
Duration of time windows.



### groupColumns

List of columns to group by. Default is `[]`.



### unit

Time duration to use when calculating the rate. Default is `1s`.



### tables

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




## Examples

### Calculate the average rate of change in data

```js
import "experimental/aggregate"
import "sampledata"

data =
    sampledata.int()
        |> range(start: sampledata.start, stop: sampledata.stop)

data
    |> aggregate.rate(every: 30s, unit: 1s, groupColumns: ["tag"])

```

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{{% expand "View example input and output" %}}

#### Input data

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

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


#### Output data

| *_start              | *_stop               | *tag | _value  | _time                |
| -------------------- | -------------------- | ---- | ------- | -------------------- |
| 2021-01-01T00:00:00Z | 2021-01-01T00:01:00Z | t1   | 1.2     | 2021-01-01T00:00:30Z |
| 2021-01-01T00:00:00Z | 2021-01-01T00:01:00Z | t1   | 1       | 2021-01-01T00:01:00Z |

| *_start              | *_stop               | *tag | _value  | _time                |
| -------------------- | -------------------- | ---- | ------- | -------------------- |
| 2021-01-01T00:00:00Z | 2021-01-01T00:01:00Z | t2   |         | 2021-01-01T00:00:30Z |
| 2021-01-01T00:00:00Z | 2021-01-01T00:01:00Z | t2   | 2.2     | 2021-01-01T00:01:00Z |

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