Mapping multiple arrays in scala

Question

I have two arrays in Scala both with the same numbers

val v = myGraph.vertices.collect.map(_._1)

which gives:

Array[org.apache.spark.graphx.VertexId] = Array(-7023794695707475841, -44591218498176864, 757355101589630892, 21619280952332745)

and another

val w = myGraph.vertices.collect.map(_._2._2)

which gives:

Array[String] = Array(2, 3, 1, 2)

and i want to create a string using

val z =  v.map("{id:" + _ + "," + "group:" + "1" + "}").mkString(",")

which gives:

String = {id:-7023794695707475841,group:1},{id:-44591218498176864,group:1},{id:757355101589630892,group:1},{id:21619280952332745,group:1}

But now instead of the hardcoded group of "1", i want to instead map in the numbers from the w array to give:

String = {id:-7023794695707475841,group:2},{id:-44591218498176864,group:3},{id:757355101589630892,group:1},{id:21619280952332745,group:2}

How do i do this?

slouc · Accepted Answer · 2016-05-15 11:15:12Z

3

There's a method in Scala collections called zip which pairs up two collections just the way you need.

val v = Array(-37581, -44864, 757102, 21625)
val w = Array(2, 3, 1, 2)

val z = v.zip(w).map { 
  case (v, w) => "{id:" + v + "," + "group:" + w + "}" 
}.mkString(",")

Value z becomes:

{id:-37581,group:2},{id:-44864,group:3},{id:757102,group:1},{id:21625,group:2}

answered May 15, 2016 at 11:15

slouc

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