CODEWITHSUNDEEP
scala
cool breeze
cool breeze

Reputation: 4811

How to find the largest value that is found within a Maps key

I have a map of type Map[String, String] with keys like:

"dealership_id_1"
"dealership_id_3"
"dealership_id_7"
"dealership_id_39"

How can I get the largest value of the ID from the keys? i.e. in this case it is 39

Would it be difficult to extract the id values into a list?
List(1, 3, 7, 39)

My map has maybe 100 keys so it should be a performance issue I would imagine.

Upvotes: 0

Views: 281

Answers (3)

tkachuko
tkachuko

Reputation: 1986

I do agree with the @Alvaro Carrasco solution but map.keys.map() actually creates new collection. I would rather stick to Iterator which does not do that:

def maxKeySuffix[T](map: Map[String, T]): Int = 
      map.keys.iterator.map(_.stripPrefix("dealership_id_").toInt).max

Upvotes: 0

Dima
Dima

Reputation: 40500

Use the regex:

val id = """_(\d+)""".r
val ids = map.keys.collect { case id(x) => x }

Upvotes: 0

Alvaro Carrasco
Alvaro Carrasco

Reputation: 6172

map.keys.map(_.stripPrefix("dealership_id_").toInt).max // 39

100 entries is not very many

Upvotes: 4

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