Convert an array to a mutable set in Scala?

Question

How does one convert a Scala Array to a mutable.Set?

It's easy to convert to an immutable.Set:

Array(1, 2, 3).toSet

But I can't find an obvious way to convert to a mutable.Set.

timday · Accepted Answer · 2011-07-08 18:02:54Z

20

scala> val s=scala.collection.mutable.Set()++Array(1,2,3)
s: scala.collection.mutable.Set[Int] = Set(2, 1, 3)

answered Jul 8, 2011 at 18:02

timday

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Comments

paradigmatic · Accepted Answer · 2011-07-08 18:32:42Z

14

scala> scala.collection.mutable.Set( Array(1,2) :_* )
res2: scala.collection.mutable.Set[Int] = Set(2, 1)

The weird :_* type ascription, forces factory method to see the array as a list of arguments.

answered Jul 8, 2011 at 18:32

paradigmatic

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Xavier Guihot · Accepted Answer · 2019-06-30 09:52:36Z

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Starting Scala 2.10, via factory builders applied with .to(factory):

Array(1, 2, 3).to[collection.mutable.Set]
// collection.mutable.Set[Int] = Set(1, 2, 3)

And starting Scala 2.13:

Array(1, 2, 3).to(collection.mutable.Set)
// collection.mutable.Set[Int] = HashSet(1, 2, 3)

Xavier Guihot

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answered Nov 20, 2016 at 22:44

Teodorico Levoff

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