---
title: tickscript.selectWindow() function
description: >
  `tickscript.selectWindow()` changes a column’s name, windows rows by time, and then applies an
  aggregate or selector function the specified column for each window of time.
menu:
  flux_v0_ref:
    name: tickscript.selectWindow
    parent: contrib/bonitoo-io/tickscript
    identifier: contrib/bonitoo-io/tickscript/selectWindow
weight: 301
flux/v0/tags: [transformations]
---

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`tickscript.selectWindow()` changes a column’s name, windows rows by time, and then applies an
aggregate or selector function the specified column for each window of time.

## TICKscript helper function
`tickscript.selectWindow` is a helper function meant to replicate TICKscript operations like the following:

```
// Rename, window, and aggregate
query("SELECT f(x) AS y")
  .groupBy(time(t), ...)
```

##### Function type signature

```js
(
    <-tables: stream[D],
    as: string,
    defaultValue: A,
    every: duration,
    fn: (<-: stream[B], column: string) => stream[C],
    ?column: string,
) => stream[E] where B: Record, C: Record, D: Record, E: Record
```

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

## Parameters

### column

Column to operate on. Default is _value.



### fn
({{< req >}})
Aggregate or selector function to apply.



### as
({{< req >}})
New column name.



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



### defaultValue
({{< req >}})
Default fill value for null values in column.
Must be the same data type as column.



### tables

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




## Examples

### Change the name of, window, and then aggregate the value column

```js
import "contrib/bonitoo-io/tickscript"

data
    |> tickscript.selectWindow(fn: sum, as: "example-name", every: 1h, defaultValue: 0)

```

{{< 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

| _time                | *_start              | *_stop               | *tag | example-name  |
| -------------------- | -------------------- | -------------------- | ---- | ------------- |
| 2021-01-01T00:01:00Z | 2021-01-01T00:00:00Z | 2021-01-01T00:01:00Z | t1   | 51            |

| _time                | *_start              | *_stop               | *tag | example-name  |
| -------------------- | -------------------- | -------------------- | ---- | ------------- |
| 2021-01-01T00:01:00Z | 2021-01-01T00:00:00Z | 2021-01-01T00:01:00Z | t2   | 53            |

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