Scala pattern matching - subset on list containing strings

Question

I want to subset on people's names whose surnames are in names.

The following isn't working

val names = List("Smith","Adams","Crawford")
val people =List("Billy Jean","Will Morten","Lenhardt Peterson","Lauryn Crawford","George Smith","Priscilla Adams")

people.filter(p=> names.exists(p.name.contains))

What you're doing here is not pattern matching. Read more at docs.scala-lang.org/tutorials/tour/pattern-matching.html, and what is p.name anyway? That's a compilation error. — The_Tourist
– The_Tourist, Commented Dec 11, 2016 at 16:28

jwvh · Accepted Answer · 2016-12-12 00:20:27Z

1

Surnames come in all sorts of confusing configurations.

val names = List("Smith","von Braun","Jones","de Kooning")
val people =List("Billy Jean","Will Morten","Lenhardt Peterson",
  "Lauryn Crawford","George Smith","Priscilla Adams",
  "Wernher von Braun", "Diederik Arnoldus De Beer", "Willem de Kooning")

names.flatMap(n => people.find(_.matches(s".* $n")))
// res0: List[String] = List(George Smith, Wernher von Braun, Willem de Kooning)

answered Dec 12, 2016 at 0:20

jwvh

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Yuval Itzchakov · Accepted Answer · 2016-12-12 12:21:57Z

1

The naive and not most effecient solution:

val names = Set("Smith","Adams","Crawford")
val people = List("Billy Jean","Will Morten",
                  "Lenhardt Peterson","Lauryn Crawford", 
                  "George Smith","Priscilla Adams")

people.filter(x => names.contains(x.split(" ").lastOption.getOrElse("")))
      .foreach(println)

Results in:

Lauryn Crawford
George Smith
Priscilla Adams

edited Dec 12, 2016 at 12:21

answered Dec 11, 2016 at 14:49

Yuval Itzchakov

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