The operation about Merge two tuples

Question

Now there are two thus tuples.

1st tuple:((A,1),(B,3),(D,5)......)
2nd tuple:((A,3),(B,1),(E,6)......)

And the function is to merge those two tuples to this.

((A,1,3),(B,3,1),(D,5,0),(E,0,6)......)

If the first tuple contains a key that is not in the second tuple, set the value to 0, and vice versa. How could I code this function in scala?

Possible duplicate of https://stackoverflow.com/questions/13074031/how-to-merge-two-lists-of-tuples — ben, Jun 28 '18 at 08:05

score 0 · Answer 1 · answered Jun 28 '18 at 08:15

Lets say you get the input in the format

val tuple1: List[(String, Int)] = List(("A",1),("B",3),("D",5),("E",0))
val tuple2: List[(String, Int)] = List(("A",3),("B",1),("D",6))

You can write a merge function as

def merge(tuple1: List[(String, Int)],tuple2: List[(String, Int)]) =
{
  val map1 = tuple1.toMap
  val map2 = tuple2.toMap

  map1.map{ case (k,v) =>
    (k,v,map2.get(k).getOrElse(0))
  }
}

On calling the function

merge(tuple1,tuple2)

You will get the output as

res0: scala.collection.immutable.Iterable[(String, Int, Int)] = List((A,1,3), (B,3,1), (D,5,6), (E,0,0))

Please let me know if that answers your question.

score 0 · Answer 2 · answered Jun 28 '18 at 08:41

val t1= List(("A",1),("B",3),("D",5),("E",0))
val t2= List(("A",3),("B",1),("D",6),("H",5))
val t3 = t2.filter{ case (k,v) => !t1.exists(case (k1,_) => k1==k)) }.map{case (k,_) => (k,0)}
val t4 = t1.filter{ case (k,v) => !t2.exists{case (k1,_) => k1==k} }.map{case (k,_) => (k,0)}
val t5=(t1 ++ t3).sortBy{case (k,v) => k}
val t6=(t2 ++ t4).sortBy{case (k,v) => k}
t5.zip(t6).map{case ((k,v1),(_,v2)) => (k,v1,v2) }
res: List[(String, Int, Int)] = List(("A", 1, 3), ("B", 3, 1), ("D", 5, 6), ("E", 0, 0), ("H", 0, 5))

In terms of what's happening here t3 and t4 - find the missing value in t1 and t2 respectively and add them with a zero value t5 and t6 sort the unified list (t1 with t3 and t2 with t4). Lastly they are zipped together and transformed to the desired output

The operation about Merge two tuples

2 Answers2