events.duration() function
events.duration() is a user-contributed function maintained by
the package author.
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
For more information, see Function type signatures.
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
import "array"
import "contrib/tomhollingworth/events"
data
|> events.duration(unit: 1m, stop: 2020-01-02T00:00:00Z)
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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