Sliding window for lists

[atifaziz]

Propose to add window function for lists that provides a sliding window of a given size over the input. The result is an array of windows where is window is an array of always the given size.

Signature is:

Number -> [a] -> [[a]]

Usage:

[1 to 5] |> window 3
# => [ [ 1, 2, 3 ], [ 2, 3, 4 ], [ 3, 4, 5 ] ]

[gkz]

I have reservations about the name, as window is a global variable in the browser environment.

Also, I was wondering what kind of use-cases you envision.

[atifaziz]

Could instead call it windowed as F# does.

One common use-case is of sliding window is calculating a moving average over, for example, time series, as in:

[Math.random! for i til 30] |> window 7 |> map mean

[atifaziz]

Another suggestion for name would be windows unless the longer sliding-window seems clear & concise enough.

[michaelficarra]

Related underscore.js proposals for _.sliding and _.groupsOf: jashkenas/underscore#714 jashkenas/underscore#696