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promql.changes() function

content/flux/v0/stdlib/internal/promql/changes.md

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promql.changes() implements functionality equivalent to PromQL's changes() function.

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

Function type signature
js
(<-tables: stream[{A with _value: float}]) => stream[{B with _value: float}]

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

Parameters

tables

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

Examples

Return the number of times that values in a series change

js
import "internal/promql"
import "sampledata"

sampledata.float()
    |> promql.changes()

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

Input data

_time*tag_value
2021-01-01T00:00:00Zt1-2.18
2021-01-01T00:00:10Zt110.92
2021-01-01T00:00:20Zt17.35
2021-01-01T00:00:30Zt117.53
2021-01-01T00:00:40Zt115.23
2021-01-01T00:00:50Zt14.43
_time*tag_value
2021-01-01T00:00:00Zt219.85
2021-01-01T00:00:10Zt24.97
2021-01-01T00:00:20Zt2-3.75
2021-01-01T00:00:30Zt219.77
2021-01-01T00:00:40Zt213.86
2021-01-01T00:00:50Zt21.86

Output data

*tag_value
t15
*tag_value
t25

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