---
title: experimental.window() function
description: >
  `experimental.window()` groups records based on time.
menu:
  flux_v0_ref:
    name: experimental.window
    parent: experimental
    identifier: experimental/window
weight: 101
flux/v0/tags: [transformations, date/time]
introduced: 0.106.0
---

<!------------------------------------------------------------------------------

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`experimental.window()` groups records based on time.

`_start` and `_stop` columns are updated to reflect the bounds of
the window the row's time value is in.
Input tables must have `_start`, `_stop`, and `_time` columns.

A single input record can be placed into zero or more output tables depending
on the specific windowing function.

By default the start boundary of a window will align with the Unix epoch
modified by the offset of the `location` option.

#### Calendar months and years
`every`, `period`, and `offset` support all valid duration units, including
calendar months (`1mo`) and years (`1y`).

##### Function type signature

```js
(
    <-tables: stream[{A with _time: time, _stop: time, _start: time}],
    ?createEmpty: bool,
    ?every: duration,
    ?location: {zone: string, offset: duration},
    ?offset: duration,
    ?period: duration,
) => stream[{A with _time: time, _stop: time, _start: time}]
```

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

## Parameters

### every

Duration of time between windows. Default is the `0s`.



### period

Duration of the window. Default is `0s`.

Period is the length of each interval.
It can be negative, indicating the start and stop boundaries are reversed.

### offset

Duration to shift the window boundaries by. Default is 0s.

`offset` can be negative, indicating that the offset goes backwards in time.

### location

Location used to determine timezone. Default is the `location` option.



### createEmpty

Create empty tables for empty windows. Default is `false`.



### tables

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




## Examples

- [Window data into thirty second intervals](#window-data-into-thirty-second-intervals)
- [Window by calendar month](#window-by-calendar-month)

### Window data into thirty second intervals

```js
import "experimental"

data
    |> experimental.window(every: 30s)

```

{{< expand-wrapper >}}
{{% 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               | _time                | _value  | *tag |
| -------------------- | -------------------- | -------------------- | ------- | ---- |
| 2021-01-01T00:00:00Z | 2021-01-01T00:00:30Z | 2021-01-01T00:00:00Z | -2      | t1   |
| 2021-01-01T00:00:00Z | 2021-01-01T00:00:30Z | 2021-01-01T00:00:10Z | 10      | t1   |
| 2021-01-01T00:00:00Z | 2021-01-01T00:00:30Z | 2021-01-01T00:00:20Z | 7       | t1   |

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

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

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

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

### Window by calendar month

```js
import "experimental"

data
    |> experimental.window(every: 1mo)

```

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

#### Input data

| *_start              | *_stop               | _time                | _value  |
| -------------------- | -------------------- | -------------------- | ------- |
| 2021-01-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-01-01T00:00:00Z | 32.1    |
| 2021-01-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-01-02T00:00:00Z | 32.9    |
| 2021-01-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-01-03T00:00:00Z | 33.2    |
| 2021-01-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-02-01T00:00:00Z | 38.3    |
| 2021-01-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-02-02T00:00:00Z | 38.4    |
| 2021-01-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-02-03T00:00:00Z | 37.8    |


#### Output data

| *_start              | *_stop               | _time                | _value  |
| -------------------- | -------------------- | -------------------- | ------- |
| 2021-01-01T00:00:00Z | 2021-02-01T00:00:00Z | 2021-01-01T00:00:00Z | 32.1    |
| 2021-01-01T00:00:00Z | 2021-02-01T00:00:00Z | 2021-01-02T00:00:00Z | 32.9    |
| 2021-01-01T00:00:00Z | 2021-02-01T00:00:00Z | 2021-01-03T00:00:00Z | 33.2    |

| *_start              | *_stop               | _time                | _value  |
| -------------------- | -------------------- | -------------------- | ------- |
| 2021-02-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-02-01T00:00:00Z | 38.3    |
| 2021-02-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-02-02T00:00:00Z | 38.4    |
| 2021-02-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-02-03T00:00:00Z | 37.8    |

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