docs-v2/content/flux/v0/stdlib/contrib/tomhollingworth/events/duration.md

title	description	menu	weight	flux/v0/tags
events.duration() function	`events.duration()` calculates the duration of events.	flux_v0_ref name parent identifier events.duration contrib/tomhollingworth/events contrib/tomhollingworth/events/duration	301	transformations events

events.duration() calculates the duration of events.

The function determines the time between a record and the subsequent record and associates the duration with the first record (start of the event). To calculate the duration of the last event, the function compares the timestamp of the final record to the timestamp in the stopColumn or the specified stop time.

Similar functions

events.duration() is similar to elapsed() and stateDuration(), but differs in important ways:

• elapsed() drops the first record. events.duration() does not.
• stateDuration() calculates the total time spent in a state (determined by a predicate function). events.duration() returns the duration between all records and their subsequent records.

See the example below.

Function type signature

(
    <-tables: stream[A],
    ?columnName: string,
    ?stop: time,
    ?stopColumn: string,
    ?timeColumn: string,
    ?unit: duration,
) => stream[B] where A: Record, B: Record

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

Parameters

unit

Duration unit of the calculated state duration. Default is 1ns.

columnName

Name of the result column. Default is "duration".

timeColumn

Name of the time column. Default is "_time".

stopColumn

Name of the stop column. Default is "_stop".

stop

The latest time to use when calculating results.

If provided, stop overrides the time value in the stopColumn.

tables

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

Examples

• Calculate the duration of states
• Compared to similar functions

Calculate the duration of states

import "array"
import "contrib/tomhollingworth/events"

data
    |> events.duration(unit: 1m, stop: 2020-01-02T00:00:00Z)

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Input data

_time	state
2020-01-01T00:00:00Z	ok
2020-01-01T00:12:34Z	warn
2020-01-01T00:25:01Z	ok
2020-01-01T16:07:55Z	crit
2020-01-01T16:54:21Z	warn
2020-01-01T18:20:45Z	ok

Output data

_time	state	duration
2020-01-01T00:00:00Z	ok	12
2020-01-01T00:12:34Z	warn	12
2020-01-01T00:25:01Z	ok	942
2020-01-01T16:07:55Z	crit	46
2020-01-01T16:54:21Z	warn	86
2020-01-01T18:20:45Z	ok	339

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Compared to similar functions

The example below includes output values of events.duration(), elapsed(), and stateDuration() related to the _time and state values of input data.

import "array"
import "contrib/tomhollingworth/events"

union(
    tables: [
        data
            |> events.duration(unit: 1m, stop: 2020-01-02T00:00:00Z)
            |> map(
                fn: (r) =>
                    ({
                        _time: r._time,
                        state: r.state,
                        function: "events.Duration()",
                        value: r.duration,
                    }),
            ),
        data
            |> elapsed(unit: 1m)
            |> map(
                fn: (r) =>
                    ({_time: r._time, state: r.state, function: "elapsed()", value: r.elapsed}),
            ),
        data
            |> stateDuration(unit: 1m, fn: (r) => true)
            |> map(
                fn: (r) =>
                    ({
                        _time: r._time,
                        state: r.state,
                        function: "stateDuration()",
                        value: r.stateDuration,
                    }),
            ),
    ],
)
    |> pivot(rowKey: ["_time", "state"], columnKey: ["function"], valueColumn: "value")

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Output data

_time	state	events.Duration()	elapsed()	stateDuration()
2020-01-01T00:00:00Z	ok	12		0
2020-01-01T00:12:34Z	warn	12	12	12
2020-01-01T00:25:01Z	ok	942	12	25
2020-01-01T16:07:55Z	crit	46	942	967
2020-01-01T16:54:21Z	warn	86	46	1014
2020-01-01T18:20:45Z	ok	339	86	1100

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