CODEWITHSUNDEEP
scala
jbx
jbx

Reputation: 22128

Efficiently mapping members to their owning structure

Lets say I have the class Family which has a structure of members of the family inside it, not really relevant for this problem as long as there is a function provided by Family called def member(m : Member) : Boolean which returns true if the member m is 'part' of the family.

Most importantly however, a member can be part of multiple families.

I have a separate list of all the Members and wish to create a mapping between member and family for fast lookup.

So I have something like this:

val allMembers : Set[Member] = getAllMembers()
val allFamilies : Set[Family] = getAllFamilies()

val memberFamilyMap : Map[Member, Set[Family]] = ???

What is the most efficient way to create the above memberFamilyMap given the Family.member function, and that a member can be a member of multiple families? I am trying to use a for-comprehension with generators of the two, but things got a bit hairy (I am a bit new to Scala)

Upvotes: 2

Views: 49

Answers (1)

Kigyo
Kigyo

Reputation: 5768

I would do it like this:

 allMembers.map(m => m -> allFamilies.filter(_.member(m))).toMap

There might be something more efficient though.

Upvotes: 5

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