docs-v2/content/flux/v0.x/stdlib/experimental/aligntime.md

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---
title: experimental.alignTime() function
description: >
`experimental.alignTime()` shifts time values in input tables to all start at a common start time.
menu:
flux_0_x_ref:
name: experimental.alignTime
parent: experimental
identifier: experimental/alignTime
weight: 101
flux/v0.x/tags: [transformations, data/time]
introduced: 0.66.0
---
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`experimental.alignTime()` shifts time values in input tables to all start at a common start time.
##### Function type signature
```js
(<-tables: stream[B], ?alignTo: A) => stream[C] where B: Record, C: Record
```
{{% caption %}}For more information, see [Function type signatures](/flux/v0.x/function-type-signatures/).{{% /caption %}}
## Parameters
### alignTo
Time to align tables to. Default is `1970-01-01T00:00:00Z`.
### tables
Input data. Default is piped-forward data (`<-`).
## Examples
### Compare month-over-month values
1. Window data by calendar month creating two separate tables (one for January and one for February).
2. Align tables to `2021-01-01T00:00:00Z`.
Each output table represents data from a calendar month.
When visualized, data is still grouped by month, but timestamps are aligned
to a common start time and values can be compared by time.
```js
import "experimental"
data
|> window(every: 1mo)
|> experimental.alignTime(alignTo: 2021-01-01T00:00:00Z)
```
{{< expand-wrapper >}}
{{% expand "View example input and ouput" %}}
#### 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 | 2021-01-04T00:00:00Z | 34 |
| 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 |
| 2021-01-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-02-04T00:00:00Z | 37.5 |
#### 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 |
| 2021-01-01T00:00:00Z | 2021-02-01T00:00:00Z | 2021-01-04T00:00:00Z | 34 |
| *_start | *_stop | _time | _value |
| -------------------- | -------------------- | -------------------- | ------- |
| 2021-02-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-01-01T00:00:00Z | 38.3 |
| 2021-02-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-01-02T00:00:00Z | 38.4 |
| 2021-02-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-01-03T00:00:00Z | 37.8 |
| 2021-02-01T00:00:00Z | 2021-03-01T00:00:00Z | 2021-01-04T00:00:00Z | 37.5 |
{{% /expand %}}
{{< /expand-wrapper >}}