print scala array of tuples with a map

Question

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

What you have is functional ... I am not sure you can get something "more functional" that that. — marios
– marios, Commented Nov 7, 2015 at 17:16
@marios what I meant with functional is using map() or flatMap() or something similar.. — Andrea Iacono
– Andrea Iacono, Commented Nov 7, 2015 at 18:15

marios · Accepted Answer · 2015-11-07 18:34:00Z

1

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'") }

answered Nov 7, 2015 at 18:34

marios

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Tesseract · Accepted Answer · 2015-11-07 17:11:47Z

1

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

answered Nov 7, 2015 at 17:11

Tesseract

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Fatih Donmez · Accepted Answer · 2015-11-07 17:18:39Z

1

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