What is the correct way to get a subarray in Scala?
An example of extracting specific columns from a 2D Scala Array (original_array):
import scala.collection.mutable.ArrayBuffer
val sub_array = ArrayBuffer[Array[String]]()
val columns_subset: Seq[String] = Seq("ColumnA", "ColumnB", "ColumnC")
val columns_original = original_array(0)
for (column_now <- columns_subset) {
sub_array += original_array.map{_(columns_original.indexOf(column_now))}
}
sub_array
Imagine you have an array with elements from a
to f
scala> val array = ('a' to 'f').toArray // Array('a','b','c','d','e','f')
Then you can extract a sub-array from it in different ways:
Dropping the first n first elements with
drop(n: Int)
array.drop(2) // Array('c','d','e','f')
Take the first n elements with
take(n: Int)
array.take(4) // Array('a','b','c','d')
Select any interval of elements with
slice(from: Int, until: Int)
. Note thatuntil
is excluded.array.slice(2,4) // Array('c','d')
The slice method is stricly equivalent to:
array.take(4).drop(2) // Array('c','d')
Exclude the last n elements with
dropRight(n: Int)
:array.dropRight(4) // Array('a','b')
Select the last n elements with
takeRight(n: Int)
:array.takeRight(4) // Array('c','d','e','f')
Reference: Official documentation
You can call the slice method:
scala> Array("foo", "hoo", "goo", "ioo", "joo").slice(1, 4)
res6: Array[java.lang.String] = Array(hoo, goo, ioo)
It works like in python.