CODEWITHSUNDEEP
scalafunctional-programming
Andrea Iacono
Andrea Iacono

Reputation: 802

print scala array of tuples with a map

I have an Array of Tuple2 that contains a String and a map, and I'd like to print for each tuple2 as many rows as the number of keys of the map. This is what I wrote:

val a = Array(
           ("foo", HashMap(1->"f1", 2->"f2")),
           ("bar", HashMap(1->"b1", 2->"b2"))
        )

for (sourceNode <- a) {
   for (destNode <- sourceNode._2) {
     println("value [" + sourceNode._1 + "] for [" + destNode._1 + "] is '" + destNode._2 + "'")
   }
 }

and here is the result:

value [foo] for [1] is 'f1'
value [foo] for [2] is 'f2'
value [bar] for [1] is 'b1'
value [bar] for [2] is 'b2'

The result is correct, but is there a more concise (and functional) way to obtain this result?

Thanks, Andrea

Upvotes: 0

Views: 2461

Answers (3)

marios
marios

Reputation: 8996

I think the OP is looking for a solution using map and flatMap (instead of the syntactic sugar of for-comprehensions).

Here is one attempt to do that. First you decompose the (key,Map) pair into (key1,key2,value) tuple and then you just provide a print method. Here is the code: 

val a = Array(
           ("foo", Map(1->"f1", 2->"f2")),
           ("bar", Map(1->"b1", 2->"b2"))
        )

a.flatMap{
   case(k,theMap) => theMap.map(e => (k,e._1,e._2))
}.foreach{ case(k1,k2,v) => println(s"value [$k1] for [$k2] is '$v'") }

Upvotes: 1

Fatih Donmez
Fatih Donmez

Reputation: 4347

Similar to your solution with foreach 

a foreach { t => 
    t._2 foreach { m =>
      println("value [" + t._1 + "] for [" + m._1 + "] is '" + m._2 + "'")
    }
}

Upvotes: 1

Tesseract
Tesseract

Reputation: 8139

You could do this

for ((name, map) <- a) {
  for ((key, value) <- map) {
    println("value [" + name + "] for [" + key + "] is '" + value + "'")
  }
}

But you can make it even more concise

for {
  (name, map) <- a
  (key, value) <- map
} println(s"value [$name] for [$key] is '$value'")

Here is some more information on for comprehensions http://docs.scala-lang.org/tutorials/tour/sequence-comprehensions.html

Upvotes: 1

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