How to assign elements of an array from another array using indexes in Scala/Java?

Question

I want to assign a part of an array to a part of another array in Scala. For example, I want to do the Scala or Java equivalent of the following Python code.

x[i:j] = y[k:l]

How can I do that in Scala or even Java?

Answer 1

You can use a combination of .patch and .slice :

scala> val a = Array.range(1, 20)
a: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)

scala> val b = Array.range(30, 50)
b: Array[Int] = Array(30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)

scala> a.patch(5, b.slice(5, 10), 5)
res5: Array[Int] = Array(1, 2, 3, 4, 5, 35, 36, 37, 38, 39, 11, 12, 13, 14, 15, 16, 17, 18, 19)

The parameters of .slice are:

• the element to start from ( i in your python exemple)

• the array to insert ( y[k:l] , here using .slice to select from k to l )

• the number of element to replace in the array (unclear about what happens in your exemple when i:j is smaller than k:l , but I would guess it would be ji here)