---
title: fill() function
description: fill() replaces all null values in input tables with a non-null value.
url: https://docs.influxdata.com/flux/v0/stdlib/universe/fill/
estimated_tokens: 2294
product: Flux
version: v0
---

# fill() function

-   Flux 0.14.0+
-   View InfluxDB support

`fill()` replaces all null values in input tables with a non-null value.

Output tables are the same as the input tables with all null values replaced in the specified column.

##### Function type signature

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

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

## Parameters

### column

Column to replace null values in. Default is `_value`.

### value

Constant value to replace null values with.

Value type must match the type of the specified column.

### usePrevious

Replace null values with the previous non-null value. Default is `false`.

### tables

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

## Examples

-   [Fill null values with a specified non-null value](#fill-null-values-with-a-specified-non-null-value)
-   [Fill null values with the previous non-null value](#fill-null-values-with-the-previous-non-null-value)

### Fill null values with a specified non-null value

```js
import "sampledata"

sampledata.int(includeNull: true)
    |> fill(value: 0)
```

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

View example input and output

#### Input data

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

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z |  | 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 |  | t2 |
| 2021-01-01T00:00:50Z | 1 | t2 |

#### Output data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | -2 | t1 |
| 2021-01-01T00:00:10Z | 0 | t1 |
| 2021-01-01T00:00:20Z | 7 | t1 |
| 2021-01-01T00:00:30Z | 0 | t1 |
| 2021-01-01T00:00:40Z | 0 | t1 |
| 2021-01-01T00:00:50Z | 4 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 0 | 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 | 0 | t2 |
| 2021-01-01T00:00:50Z | 1 | t2 |

### Fill null values with the previous non-null value

```js
import "sampledata"

sampledata.int(includeNull: true)
    |> fill(usePrevious: true)
```

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

View example input and output

#### Input data

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

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z |  | 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 |  | t2 |
| 2021-01-01T00:00:50Z | 1 | t2 |

#### Output data

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

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z |  | 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 | 19 | t2 |
| 2021-01-01T00:00:50Z | 1 | t2 |

#### Related

-   [Fill null values in data](/influxdb/v2/query-data/flux/fill/)
-   [InfluxQL – FILL](/influxdb/v1/query_language/explore-data/#group-by-time-intervals-and-fill)

[transformations](/flux/v0/tags/transformations/)