---
title: monitor.stateChangesOnly() function
description: >
  `monitor.stateChangesOnly()` takes a stream of tables that contains a _level column
  and returns a stream of tables grouped by `_level` where each record
  represents a state change.
menu:
  flux_v0_ref:
    name: monitor.stateChangesOnly
    parent: influxdata/influxdb/monitor
    identifier: influxdata/influxdb/monitor/stateChangesOnly
weight: 301
flux/v0/tags: [transformations]
introduced: 0.65.0
---

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

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`monitor.stateChangesOnly()` takes a stream of tables that contains a _level column
and returns a stream of tables grouped by `_level` where each record
represents a state change.



##### Function type signature

```js
(<-tables: stream[{A with _level: B}]) => stream[C] where B: Equatable, C: Record
```

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

## Parameters

### tables

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




## Examples

### Return records representing state changes

```js
import "array"
import "influxdata/influxdb/monitor"

data =
    array.from(
        rows: [
            {_time: 2021-01-01T00:00:00Z, _level: "ok"},
            {_time: 2021-01-01T00:01:00Z, _level: "ok"},
            {_time: 2021-01-01T00:02:00Z, _level: "warn"},
            {_time: 2021-01-01T00:03:00Z, _level: "crit"},
        ],
    )

data
    |> monitor.stateChangesOnly()

```

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{{% expand "View example input and output" %}}

#### Input data

| _time                | _level  |
| -------------------- | ------- |
| 2021-01-01T00:00:00Z | ok      |
| 2021-01-01T00:01:00Z | ok      |
| 2021-01-01T00:02:00Z | warn    |
| 2021-01-01T00:03:00Z | crit    |


#### Output data

| _time                | *_level |
| -------------------- | ------- |
| 2021-01-01T00:03:00Z | crit    |

| _time                | *_level |
| -------------------- | ------- |
| 2021-01-01T00:02:00Z | warn    |

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