Set[A] from List[A] based on a field of A

Question

I have a class:

class Product {

    val productID = ...
    val weight = ...
    val size = ....

     .....[more fields]....

}

I have a List[Product] which contains the same product multiple times. How can I convert the list into a Set[Product] using productID as the 'unique' value so that each Product is only included once?

thanks

Ashalynd · Accepted Answer · 2014-08-25T11:18:26.200

1

There is a standard way to do it:

val a = List(a1, a2...)

val as = a.toSet

If you mean that you have products with the same ID, but different, and you would be OK with picking whatever product, then you can do something like that:

val a = List(a1, a2...)
val a_ids = a map(_.productId) toSet

val products = a_ids.flatMap(id => a.find(_.productId == id))

edited Aug 25 '14 at 11:18

answered Aug 25 '14 at 11:11

Ashalynd

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thanks, but this does not produce a set of unique Products. I guess that beneath the hood each Product object is unique, however they actually have the same productID – Zuriar Aug 25 '14 at 11:14
I got it, see my update – Ashalynd Aug 25 '14 at 11:15

Set[A] from List[A] based on a field of A

1 Answers1