CODEWITHSUNDEEP
scalascala-collections
Adam Davies
Adam Davies

Reputation: 2812

Partitioning a List into more than two partitions

I have a list:

val list1 = List("male:Adam", "male:Peter", "female:Jane", "female:Sue", "female:Jo", "other:John")

I want to create two lists, one of female names and one of male names. i.e.:

List("Adam", "Peter")
List("Jane", "Sue", "Jo")

I've done this with 

val result = list1.groupBy(_.startsWith("male"))

So that result has the two lists mapped against true and false but with each element being "male:Adam" etc. But then I'd have to cycle through each list removing the male: and female: strings. This smells of non-functional.

Can anyone show how the above problem would be solved in a functional way?

Upvotes: 0

Views: 600

Answers (3)

dcastro
dcastro

Reputation: 68750

val groups = list.map(_.split(":")).groupBy(_(0)).mapValues(_.map(_(1)))

val males = groups("male")
val females = groups("female")

Upvotes: 2

Peter Neyens
Peter Neyens

Reputation: 9820

val map = list1.map(s => s.split(":") match { 
  case Array(sex, name) => (sex, name) 
})
.groupBy { case (sex, name) => sex }
.mapValues(_.map{ case (sex, name) => name })

val male = map("male")
// List(Adam, Peter)
val female = map("female")
// List(Jane, Sue, Jo)

Upvotes: 4

alatom
alatom

Reputation: 41

Use map function like 

result(true).map(_.split(":")(1))

Upvotes: 0

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