Mark Silberbauer Mark Silberbauer - 2 months ago 12
Scala Question

In Scala, how to get a slice of a list from nth element to the end of the list without knowing the length?

I'm looking for an elegant way to get a slice of a list from element n onwards without having to specify the length of the list. Lets say we have a multiline string which I split into lines and then want to get a list of all lines from line 3 onwards:

string.split("\n").slice(3,X) // But I don't know what X is...


What I'm really interested in here is whether there's a way to get hold of a reference of the list returned by the
split
call so that its length can be substituted into
X
at the time of the
slice
call, kind of like a fancy
_
(in which case it would read as
slice(3,_.length)
) ? In python one doesn't need to specify the last element of the slice.

Of course I could solve this by using a temp variable after the split, or creating a helper function with a nice syntax, but I'm just curious.

Answer

Just drop first n elements you don't need:

List(1,2,3,4).drop(2)
res0: List[Int] = List(3, 4)

or in your case:

string.split("\n").drop(2)

There is also paired method .take(n) that do the opposite thing, you can think of it as .slice(0,n).

In case you need both parts, use .splitAt:

val (left, right) = List(1,2,3,4).splitAt(2)
left: List[Int] = List(1, 2)
right: List[Int] = List(3, 4)
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