CODEWITHSUNDEEP
scalasetsortedset
user3370773
user3370773

Reputation: 455

scala sort a set of a certain class

I have a set of a certain dto i created.

The dto is named "NumericValue", and has the following class members: 1) time: Long 2) value: Double

I have a set named "points", and i want to sort it according to increasing time, i.e. 0, 1, 2, 4, 100,...

Attached is code:

val points: set(NumericValue) = numericValueSet

val setSorted = collection.immutable.SortedSet[Long]() ++ points

I did the following:

However the result isn't sorted according to time.

Thanks

Upvotes: 0

Views: 1004

Answers (1)

Sergii Lagutin
Sergii Lagutin

Reputation: 10671

Result isn't unsorted because there is not Ordering for your class.

You can explicit implement Ordered:

case class NumericValue(time: Long, value: Double) extends Ordered[NumericValue] {
  override def compare(that: NumericValue): Int =
    Ordering[Long].compare(this.time, that.time)
}

or create Ordering for your set:

val set = SortedSet[NumericValue]()(new Ordering[NumericValue]() {
  override def compare(x: NumericValue, y: NumericValue): Int =
    Ordering[Long].compare(x.time, y.time)
})

Result should be ordered:

set + NumericValue(345, 45) + NumericValue(453, 123) + NumericValue(5, 5)

res0: scala.collection.SortedSet[NumericValue] = TreeSet(NumericValue(5,5.0), NumericValue(345,45.0), NumericValue(453,123.0))

Upvotes: 9

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