docs-v2/content/flux/v0.x/stdlib/interpolate/linear.md

title	description	menu	weight	flux/v0.x/tags
interpolate.linear() function	`interpolate.linear()` inserts rows at regular intervals using linear interpolation to determine values for inserted rows.	flux_0_x_ref name parent identifier interpolate.linear interpolate interpolate/linear	101	transformations

interpolate.linear() inserts rows at regular intervals using linear interpolation to determine values for inserted rows.

Function requirements

• Input data must have _time and _value columns.
• All columns other than _time and _value must be part of the group key.

Function type signature

(<-tables: stream[{A with _value: float, _time: time}], every: duration) => stream[{A with _value: float, _time: time}]

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

Parameters

every

({{< req >}}) Duration of time between interpolated points.

tables

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

Examples

Interpolate missing data by day

import "interpolate"

data
    |> interpolate.linear(every: 1d)

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Input data

_time	_value
2021-01-01T00:00:00Z	10
2021-01-02T00:00:00Z	20
2021-01-04T00:00:00Z	40
2021-01-05T00:00:00Z	50
2021-01-08T00:00:00Z	80
2021-01-09T00:00:00Z	90

Output data

_time	_value
2021-01-01T00:00:00Z	10
2021-01-02T00:00:00Z	20
2021-01-03T00:00:00Z	30
2021-01-04T00:00:00Z	40
2021-01-05T00:00:00Z	50
2021-01-06T00:00:00Z	60
2021-01-07T00:00:00Z	70
2021-01-08T00:00:00Z	80
2021-01-09T00:00:00Z	90

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