Rulloffset

Rulloffset is a term used in data processing to describe the offset applied when performing rolling or sliding-window computations. It denotes how far the window is shifted relative to a reference position, such as the current element in a sequence. The concept is analogous to lag or lead in time series analysis, but is phrased in terms of a single offset value that governs the window’s starting point.

Formally, for a sequence x[0..n-1], a rolling computation with window size w and rulloffset r computes a statistic over the subset x[k+r .. k+r+w-1] for each valid position k. A nonzero rulloffset moves the window forward (positive) or backward (negative) from the default alignment. When rulloffset is zero, the window begins at the current index. Edge handling determines whether partial windows are allowed near the sequence ends.

In practice, rulloffset affects how rolling metrics align with input data, which is useful for creating lagged features in time-series modeling or aligning rolling statistics with events. It is not a universal standard term in all libraries; some frameworks describe similar behavior with lag, lead, or center options rather than a single rulloffset parameter.

Example: with a series [1, 2, 3, 4, 5], a window size of 3, and rulloffset of 1, the first computed window covers elements [2, 3, 4]. The resulting statistic is then associated with the position corresponding to the initial reference index, depending on implementation.

Related concepts include moving averages, rolling sums, lag, lead, and time-series alignment.