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

---
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 >}}