How to generate array of tuples from a list in scala?

Question

I have a row as below (Int,List(String))

(22,List(B00000JCDS, B000004CSZ, B00016XN6Q, B00005LLY3, B00023B1UI))

I need to generate a tuple array or any other collection as below:

(22,B00000JCDS)
(22,B000004CSZ)
(22,B00016XN6Q)
(22,B00005LLY3)
(22,B00023B1UI)

How to generate this dataset in Scala?

mohit · Accepted Answer · 2014-12-19 12:01:29Z

4

scala> a._2.map((a._1,_))
res3: List[(Int, String)] = List((22,B00000JCDS), (22,B000004CSZ), (22,B00016XN6Q), (22,B00005LLY3), (22,B00023B1UI))

where a is (22,List(B00000JCDS, B000004CSZ, B00016XN6Q, B00005LLY3, B00023B1UI))

answered Dec 19, 2014 at 12:01

mohit

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Comments

Ende Neu · Accepted Answer · 2014-12-19 11:52:13Z

1

The most readable thing which comes to mind is to use for comprehension:

scala>   val g = (22,List("B00000JCDS", "B000004CSZ", "B00016XN6Q", "B00005LLY3", "B00023B1UI"))
g: (Int, List[String]) = (22,List(B00000JCDS, B000004CSZ, B00016XN6Q, B00005LLY3, B00023B1UI))

scala>   
   |   for {
   |     fromList <- g._2
   |   } yield (g._1, fromList)

res3: List[(Int, String)] = List((22,B00000JCDS), (22,B000004CSZ), (22,B00016XN6Q), (22,B00005LLY3), (22,B00023B1UI))

If you want an array just call toArray.

answered Dec 19, 2014 at 11:52

Ende Neu

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Comments

elm · Accepted Answer · 2014-12-19 13:09:56Z

0

Several approaches to this for a given row a, as follows,

Array.fill(a._2.size)(a._1) zip a._2

(Iterator.continually(a._1) zip a._2.iterator) toArray

Array.tabulate(a._2.size)(i => (a._1, a._2(i)) )

edited Dec 19, 2014 at 13:09

answered Dec 19, 2014 at 12:20

elm

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