---
title: promql.labelReplace() function
description: >
  `promql.labelReplace()` implements functionality equivalent to
  [PromQL's `label_replace()` function](https://prometheus.io/docs/prometheus/latest/querying/functions/#label_replace).
menu:
  flux_v0_ref:
    name: promql.labelReplace
    parent: internal/promql
    identifier: internal/promql/labelReplace
weight: 201
---

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

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------------------------------------------------------------------------------->

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

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

##### Function type signature

```js
(
    <-tables: stream[{A with _value: float}],
    destination: string,
    regex: string,
    replacement: string,
    source: string,
) => stream[{B with _value: float}]
```

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

## Parameters

### tables

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



### source
({{< req >}})
Input label.



### destination
({{< req >}})
Output label.



### regex
({{< req >}})
Pattern as a regex string.



### replacement
({{< req >}})
Replacement value.