Is there a range data structure in Scala?

Question

I'm looking for a way to handle ranges in Scala. What I need to do is:

given a set of ranges and a range(A) return the range(B) where range(A) intersect range (B) is not empty

given a set of ranges and a range(A) remove/add range(A) from/to the set of ranges.

given range(A) and range(B) create a range(C) = [min(A,B), max(A,B)]

I saw something similar in java - http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/collect/RangeSet.html Though subRangeSet returns only the intersect values and not the range in the set (or list of ranges) that it intersects with.

 RangeSet rangeSet = TreeRangeSet.create();
 rangeSet.add(Range.closed(0, 10));
 rangeSet.add(Range.closed(30, 40));
 Range range = Range.closed(12, 32);
 System.out.println(rangeSet.subRangeSet(range)); //[30,32] (I need [30,40])
 System.out.println(range.span(Range.closed(30, 40))); //[12,40]

Answer 1

There is an Interval[A] type in the spire math library . This allows working with ranges of arbitrary types that define an Order . Boundaries can be inclusive, exclusive or omitted. So eg (-∞, 0.0] or [0.0, 1.0) would be possible intervals of doubles.

Here is a library intervalset for working with sets of non-overlapping intervals ( IntervalSeq or IntervalTrie ) as well as maps of intervals to arbitrary values ( IntervalMap ).

Here is a related question that describes how to use IntervalSeq with DateTime.

Note that if the type you want to use is 64bit or less (basically any primitive), IntervalTrie is extremely fast . See the Benchmarks .

Answer 2

As Tzach Zohar has mentioned in the comment, if all you need is range of Int - go for scala.collection.immutable.Range:

val rangeSet = Set(0 to 10, 30 to 40)
val r = 12 to 32
rangeSet.filter(range => range.contains(r.start) ||  range.contains(r.end))

If you need it for another underlying type - implement it by yourself, it's easy for your usecase.