---
title: promql.changes() function
description: promql.changes() implements functionality equivalent to PromQL’s changes() function.
url: https://docs.influxdata.com/flux/v0/stdlib/internal/promql/changes/
estimated_tokens: 1033
product: Flux
version: v0
---

# promql.changes() function

-   Flux 0.47.0+
-   View InfluxDB support

`promql.changes()` implements functionality equivalent to [PromQL’s `changes()` function](https://prometheus.io/docs/prometheus/latest/querying/functions/#changes).

**Important**: The `internal/promql` package is not meant for external use.

##### Function type signature

```js
(<-tables: stream[{A with _value: float}]) => stream[{B with _value: float}]
```

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

## Parameters

### tables

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

## Examples

### Return the number of times that values in a series change

```js
import "internal/promql"
import "sampledata"

sampledata.float()
    |> promql.changes()
```

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t1 | -2.18 |
| 2021-01-01T00:00:10Z | t1 | 10.92 |
| 2021-01-01T00:00:20Z | t1 | 7.35 |
| 2021-01-01T00:00:30Z | t1 | 17.53 |
| 2021-01-01T00:00:40Z | t1 | 15.23 |
| 2021-01-01T00:00:50Z | t1 | 4.43 |

| _time | *tag | _value |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | t2 | 19.85 |
| 2021-01-01T00:00:10Z | t2 | 4.97 |
| 2021-01-01T00:00:20Z | t2 | -3.75 |
| 2021-01-01T00:00:30Z | t2 | 19.77 |
| 2021-01-01T00:00:40Z | t2 | 13.86 |
| 2021-01-01T00:00:50Z | t2 | 1.86 |

#### Output data

| *tag | _value |
| --- | --- |
| t1 | 5 |

| *tag | _value |
| --- | --- |
| t2 | 5 |