CODEWITHSUNDEEP
scala
zella
zella

Reputation: 4685

How to efficient search elements

I have a collection of

case class User(id: Int, parentId: Int)

val users = Seq(User(3, 23), User(4, 17), User(22, 23),User(29, 90))

I need do efficient (less than O(n)) search by "parentId":

val testUser = User(23, 999)

val found = users.filter(u => u.parentId == testUser.id)

res: List(User(3,23), User(22,23))

How I can achive this and which data structure to use?

Upvotes: 1

Views: 117

Answers (1)

sheunis
sheunis

Reputation: 1544

Use groupBy to convert your Seq to a Map, which will give you O(1) lookup:

case class User(id: Int, parentId: Int)

val users = Seq(User(3, 23), User(4, 17), User(22, 23),User(29, 90))

val usersMap = users.groupBy(_.parentId)

val testUser = User(23, 999)

val found = usersMap.get(testUser.id)

Upvotes: 3

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