---
title: rename() function
description: >
  `rename()` renames columns in a table.
menu:
  flux_v0_ref:
    name: rename
    parent: universe
    identifier: universe/rename
weight: 101
flux/v0/tags: [transformations]
introduced: 0.7.0
---

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`rename()` renames columns in a table.

If a column in the group key is renamed, the column name in the group key is updated.

##### Function type signature

```js
(<-tables: stream[B], ?columns: A, ?fn: (column: string) => string) => stream[C] where A: Record, B: Record, C: Record
```

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

## Parameters

### columns

Record that maps old column names to new column names.



### fn

Function that takes the current column name (`column`) and returns a
new column name.



### tables

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




## Examples

- [Explicitly map column names to new column names](#explicitly-map-column-names-to-new-column-names)
- [Rename columns using a function](#rename-columns-using-a-function)
- [Conditionally rename columns using a function](#conditionally-rename-columns-using-a-function)

### Explicitly map column names to new column names

```js
import "sampledata"

sampledata.int()
    |> rename(columns: {tag: "uid", _value: "val"})

```

{{< expand-wrapper >}}
{{% expand "View example input and output" %}}

#### Input data

| _time                | _value  | *tag |
| -------------------- | ------- | ---- |
| 2021-01-01T00:00:00Z | -2      | t1   |
| 2021-01-01T00:00:10Z | 10      | t1   |
| 2021-01-01T00:00:20Z | 7       | t1   |
| 2021-01-01T00:00:30Z | 17      | t1   |
| 2021-01-01T00:00:40Z | 15      | t1   |
| 2021-01-01T00:00:50Z | 4       | t1   |

| _time                | _value  | *tag |
| -------------------- | ------- | ---- |
| 2021-01-01T00:00:00Z | 19      | t2   |
| 2021-01-01T00:00:10Z | 4       | t2   |
| 2021-01-01T00:00:20Z | -3      | t2   |
| 2021-01-01T00:00:30Z | 19      | t2   |
| 2021-01-01T00:00:40Z | 13      | t2   |
| 2021-01-01T00:00:50Z | 1       | t2   |


#### Output data

| _time                | val  | *uid |
| -------------------- | ---- | ---- |
| 2021-01-01T00:00:00Z | -2   | t1   |
| 2021-01-01T00:00:10Z | 10   | t1   |
| 2021-01-01T00:00:20Z | 7    | t1   |
| 2021-01-01T00:00:30Z | 17   | t1   |
| 2021-01-01T00:00:40Z | 15   | t1   |
| 2021-01-01T00:00:50Z | 4    | t1   |

| _time                | val  | *uid |
| -------------------- | ---- | ---- |
| 2021-01-01T00:00:00Z | 19   | t2   |
| 2021-01-01T00:00:10Z | 4    | t2   |
| 2021-01-01T00:00:20Z | -3   | t2   |
| 2021-01-01T00:00:30Z | 19   | t2   |
| 2021-01-01T00:00:40Z | 13   | t2   |
| 2021-01-01T00:00:50Z | 1    | t2   |

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

### Rename columns using a function

```js
import "sampledata"

sampledata.int()
    |> rename(fn: (column) => "${column}_new")

```

{{< expand-wrapper >}}
{{% expand "View example input and output" %}}

#### Input data

| _time                | _value  | *tag |
| -------------------- | ------- | ---- |
| 2021-01-01T00:00:00Z | -2      | t1   |
| 2021-01-01T00:00:10Z | 10      | t1   |
| 2021-01-01T00:00:20Z | 7       | t1   |
| 2021-01-01T00:00:30Z | 17      | t1   |
| 2021-01-01T00:00:40Z | 15      | t1   |
| 2021-01-01T00:00:50Z | 4       | t1   |

| _time                | _value  | *tag |
| -------------------- | ------- | ---- |
| 2021-01-01T00:00:00Z | 19      | t2   |
| 2021-01-01T00:00:10Z | 4       | t2   |
| 2021-01-01T00:00:20Z | -3      | t2   |
| 2021-01-01T00:00:30Z | 19      | t2   |
| 2021-01-01T00:00:40Z | 13      | t2   |
| 2021-01-01T00:00:50Z | 1       | t2   |


#### Output data

| _time_new            | _value_new  | *tag_new |
| -------------------- | ----------- | -------- |
| 2021-01-01T00:00:00Z | -2          | t1       |
| 2021-01-01T00:00:10Z | 10          | t1       |
| 2021-01-01T00:00:20Z | 7           | t1       |
| 2021-01-01T00:00:30Z | 17          | t1       |
| 2021-01-01T00:00:40Z | 15          | t1       |
| 2021-01-01T00:00:50Z | 4           | t1       |

| _time_new            | _value_new  | *tag_new |
| -------------------- | ----------- | -------- |
| 2021-01-01T00:00:00Z | 19          | t2       |
| 2021-01-01T00:00:10Z | 4           | t2       |
| 2021-01-01T00:00:20Z | -3          | t2       |
| 2021-01-01T00:00:30Z | 19          | t2       |
| 2021-01-01T00:00:40Z | 13          | t2       |
| 2021-01-01T00:00:50Z | 1           | t2       |

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

### Conditionally rename columns using a function

```js
import "sampledata"

sampledata.int()
    |> rename(
        fn: (column) => {
            _newColumnName = if column =~ /^_/ then "${column} (Reserved)" else column

            return _newColumnName
        },
    )

```

{{< expand-wrapper >}}
{{% expand "View example input and output" %}}

#### Input data

| _time                | _value  | *tag |
| -------------------- | ------- | ---- |
| 2021-01-01T00:00:00Z | -2      | t1   |
| 2021-01-01T00:00:10Z | 10      | t1   |
| 2021-01-01T00:00:20Z | 7       | t1   |
| 2021-01-01T00:00:30Z | 17      | t1   |
| 2021-01-01T00:00:40Z | 15      | t1   |
| 2021-01-01T00:00:50Z | 4       | t1   |

| _time                | _value  | *tag |
| -------------------- | ------- | ---- |
| 2021-01-01T00:00:00Z | 19      | t2   |
| 2021-01-01T00:00:10Z | 4       | t2   |
| 2021-01-01T00:00:20Z | -3      | t2   |
| 2021-01-01T00:00:30Z | 19      | t2   |
| 2021-01-01T00:00:40Z | 13      | t2   |
| 2021-01-01T00:00:50Z | 1       | t2   |


#### Output data

| _time (Reserved)     | _value (Reserved)  | *tag |
| -------------------- | ------------------ | ---- |
| 2021-01-01T00:00:00Z | -2                 | t1   |
| 2021-01-01T00:00:10Z | 10                 | t1   |
| 2021-01-01T00:00:20Z | 7                  | t1   |
| 2021-01-01T00:00:30Z | 17                 | t1   |
| 2021-01-01T00:00:40Z | 15                 | t1   |
| 2021-01-01T00:00:50Z | 4                  | t1   |

| _time (Reserved)     | _value (Reserved)  | *tag |
| -------------------- | ------------------ | ---- |
| 2021-01-01T00:00:00Z | 19                 | t2   |
| 2021-01-01T00:00:10Z | 4                  | t2   |
| 2021-01-01T00:00:20Z | -3                 | t2   |
| 2021-01-01T00:00:30Z | 19                 | t2   |
| 2021-01-01T00:00:40Z | 13                 | t2   |
| 2021-01-01T00:00:50Z | 1                  | t2   |

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