How can I get a list of a? ```data class Item(val a: Int, val b: Int) val items = listOf(Item(1,2),...

# android

[Ahmed Sellami]

How can I get a list of a?

data class Item(val a: Int, val b: Int)

val items = listOf(Item(1,2), Item(3,4))

val aList = // [1,3]

[Jakub Syty]

val aList = items.map { it.a }

[Ahmed Sellami]

How can I do the inverse? Construct items from aList and bList in a neat way?

[Jakub Syty]

aList zip bList will give you list of pairs, you can also provide a transform function

[Jakub Syty]

aList.zip(bList) { (a, b) ->
    Item(a, b)
}

[Ahmed Sellami]

zip works, but couldn't provide a transform function:
ERROR:
Iterable<TypeVariable(T)>.zip(Array<out TypeVariable(R)>, (a: TypeVariable(T), b: TypeVariable(R)) → TypeVariable(V)) where T = TypeVariable(T), R = TypeVariable(R), V = TypeVariable(V) for inline fun <T, R, V> Iterable<T>.zip(other: Array<out R>, transform: (a: T, b: R) → V): List<V> defined in kotlin.collections
Iterable<TypeVariable(T)>.zip(Iterable<TypeVariable(R)>, (a: TypeVariable(T), b: TypeVariable(R)) → TypeVariable(V)) where T = TypeVariable(T), R = TypeVariable(R), V = TypeVariable(V) for inline fun <T, R, V> Iterable<T>.zip(other: Iterable<R>, transform: (a: T, b: R) → V): List<V> defined in kotlin.collections

[Ahmed Sellami]

So, I guess I will do this:

aList.zip(bList).map { Item(it.first, it.second) }

[Jakub Syty]

https://play.kotlinlang.org/#eyJ2ZXJzaW9uIjoiMS43LjIxIiwicGxhdGZvcm0iOiJqYXZhIiwiYXJncy[…]wiIH1cbnByaW50bG4ocmVzdWx0KSAvLyBbYTEsIGIyLCBjM11cblxufSJ9

[Jakub Syty]

just remove the parenthisis over (a, b) and it will be fine