toCollection

Appends all array elements to a mutable collection and returns it. Convenience functions toSet, toHashSet, and toMutableSet create new set instances containing only the unique elements.

Signatures

fun <T, D : Dimension, C : MutableCollection<in T>> MultiArray<T, D>.toCollection(
    destination: C
): C

fun <T, D : Dimension> MultiArray<T, D>.toSet(): Set<T>
fun <T, D : Dimension> MultiArray<T, D>.toHashSet(): HashSet<T>
fun <T, D : Dimension> MultiArray<T, D>.toMutableSet(): MutableSet<T>

Parameters

Parameter	Type	Description
`destination`	`C : MutableCollection<in T>`	Target collection to append elements to.

Returns:

toCollection: the destination with all elements added.
toSet/toHashSet/toMutableSet: a new set containing all unique elements.

Example

val a = mk.ndarray(mk[1, 2, 2, 3, 3, 3])

a.toSet()                            // {1, 2, 3}
a.toHashSet()                        // HashSet {1, 2, 3}

val list = mutableListOf(0)
a.toCollection(list)                 // [0, 1, 2, 2, 3, 3, 3]

28 February 2026