Question: This might be pretty simple questions. I have a list named **"List1"** that contain list of integer pairs as below. 

> 
> List1 = List((1,2), (3,4), (9,8), (9,10)) 
> 
> 
> 

Output should be: 

> 
> r1 = (1,3,9,9) //List((**1**,2), (**3**,4), (**9**,8), (**9**,10))  
> 
>  r2 = (2,4,8,10) //List((1,**2**), (3,**4**), (9,**8**), (9,**10**))
> 
> 
> 

```
array r1(Array[int]) should contains set of all first integers of each pair in the list.
array r2(Array[int]) should contains set of all second integers of each pair  

```

Answer: 
Just use `unzip`:

```
scala> List((1,2), (3,4), (9,8), (9,10)).unzip
res0: (List[Int], List[Int]) = (List(1, 3, 9, 9),List(2, 4, 8, 10))

```
Use foldLeft 

```
val (alist, blist) = list1.foldLeft((List.empty[Int], List.empty[Int])) { (r, c) => (r._1 ++ List(c._1), r._2 ++ List(c._2))}

```

**Scala REPL**

```
scala> val list1 = List((1, 2), (3, 4), (5, 6))
list1: List[(Int, Int)] = List((1,2), (3,4), (5,6))

scala> val (alist, blist) = list1.foldLeft((List.empty[Int], List.empty[Int])) { (r, c) => (r._1 ++ List(c._1), r._2 ++ List(c._2))}
alist: List[Int] = List(1, 3, 5)
blist: List[Int] = List(2, 4, 6)

```