windowed

Learn windowing with windowed.

windowed

windowed splits a collection into sliding windows. Each window has a given size; an optional step controls the shift.

Example: listOf(1, 2, 3, 4).windowed(2) returns [[1, 2], [2, 3], [3, 4]]. windowed(2, step = 2) gives [[1, 2], [3, 4]]; windows do not overlap. This pattern is useful for moving averages and time-series analysis.

step and partialWindows

The step parameter sets the window shift. With partialWindows = true, the trailing partial window is included.

Example: listOf(1, 2, 3, 4, 5).windowed(3, step = 2) returns [[1, 2, 3], [3, 4, 5]]. With partialWindows = true, listOf(1, 2, 3, 4, 5).windowed(3, step = 2, partialWindows = true) appends [5]. These parameters fine-tune window behavior.

Exercise Compute a moving average

In main assign the result of listOf(1, 2, 3, 4, 5).windowed(3) { it.average() } to a variable and print it with println.

Show example solution

fun main() {
    val avg = listOf(1, 2, 3, 4, 5).windowed(3) { it.average() }
    println(avg)
}

Test yourself

What does listOf(1, 2, 3, 4).windowed(2) return?
- [[1, 2], [3, 4]]
- [[1, 2], [2, 3], [3, 4]]
- [[1, 2, 3, 4]]
- [1, 2, 3, 4]
Show answer

[[1, 2], [2, 3], [3, 4]] — windowed(2) uses default step 1 to slide.

Complete the windowed call

val windows = listOf(1, 2, 3, 4).____(2)

Show answer

val windows = listOf(1, 2, 3, 4).windowed(2)

Match the windowed parts

windowed(2)

Window size
step = 2

Shift
partialWindows = true

Partial window
[[1, 2], [2, 3]]

Result

Next lesson: chunked

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