docs-v2/content/flux/v0/stdlib/universe/fill.md

title	description	menu	weight	flux/v0/tags	introduced
fill() function	`fill()` replaces all null values in input tables with a non-null value.	flux_v0_ref name parent identifier fill universe universe/fill	101	transformations	0.14.0

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

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

{{% caption %}} For more information, see Function type signatures. {{% /caption %}}

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 the previous non-null value

Fill null values with a specified non-null value

import "sampledata"

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

{{< 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		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

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

Fill null values with the previous non-null value

import "sampledata"

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

{{< 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		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

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