Removed: 1.73
The holtwinters() function has been removed from
the product.
Used to generate a trendline for a periodic dataset. The key parameter
period specifies the length of the period to be applied. This is used
after a Time Chart, as in:
timechart(...)
| holtwinters(1week)The function implements triple exponential smoothing, and adds an extra graph for every series in the graph. The computation assumes periodic data set (the period parameter specifies the length of the period), such as daily or weekly traffic measurements. The function works best when the timecharts span (width of each bucket) is a multiple of the period, as the smoothing is done in units of the buckets.
For example, a 30 day chart with a 7 day period would have 4 periods from day 2 to 30 (the first 2 days being ignored). Based on this, the first 3 periods (in this case period 1, 2 and 3) are fed into the smoothing/forecast computation, producing a "forecast" for the fourth period. Smoothing data for period 2, 3 and 4 are emitted, the last period being entirely computed.
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
alpha | number | false | Data smoothing factor in the interval [0..1]. | |
beta | number | false | Trend smoothing factor in the interval [0..1]. | |
gamma | number | false | Seasonal change smoothing in the interval [0..1]. | |
period | string | true | Defines the trend's period, such as 1week or 1day |---| see the full list of the allowed time periods at Relative Time Syntax. [a] | |
holtwinters() Examples
Show event count graph with daily aggregates and compute the weekly trend.
timechart(function=count(), span=1d)
| holtwinters(period=7d)