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.
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)
The right answer is takeRight(n)
:
"communism is sharing => resource saver".takeRight(3)
//> res0: String = ver
You can use scala's list method 'takeRight',This will not throw exception when List's length is not enough, Like this:
val t = List(1,2,3,4,5);
t.takeRight(3);
res1: List[Int] = List(3,4,5)
If list is not longer than you want take, this will not throw Exception:
val t = List(4,5);
t.takeRight(3);
res1: List[Int] = List(4,5)
get last 2 elements:
List(1,2,3,4,5).reverseIterator.take(2)