events.duration() function

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

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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

Output data

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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

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