In Kotlin, how can I take the first n elements of an array
The problem with your code that you create pairs with color constants which are Int
s (allColours
has type Array<Pair<Int, Int>>)
, but you expect Array<Pair<Color, Color>>
. What you have to do is change type pegColours
type and use take
:
var pegColours: Array<Pair<Int, Int>> = allColours.take(3).toTypedArray()
Also you have to call toTypedArray()
cause Array.take
returns List
rather than Array
. Or you can change pegColours
type as following:
var pegColours: List<Pair<Int, Int>> = allColours.take(3)
You are very close :)
val allColours = arrayOf("red", "blue", "green")
kotlin.io.println(allColours.take(2))
Will give you first two elements ["red", "blue"]
You have to specify the number of elements you want to take from the array
You need to specify the number of items you want to take.
allColours.take(3)
For a random number of random indices, you can use the following:
val indexes = arrayOf(2, 4, 6)
allColours.filterIndexed { index, s -> indexes.contains(index) }
Note that you can write an extension method for this:
fun <T> Array<T>.filterByIndices(vararg indices: Int) = filterIndexed { index, _ -> indices.contains(index) }
Alternatively, if the indices are consecutive, you can use slice:
allColours.slice(1..3)
I know you already proposed the usage of take
, but alternatively ranges and a simple map
also help to write idiomatic code as shown next:
var pegColours = (0 until 3)
.map { allColours[it] }
.toTypedArray()