CODEWITHSUNDEEP
scala
Masterbuilder
Masterbuilder

Reputation: 509

Add list values after comparison and condition check - Scala

I have three lists inside a list. 

val l = List(List(1, 0, 0), List(1, 1, 0), List(1, 0, 1))

Now the problem is to add the values inside list with condition check, basically I need to check each element wise values and if they are equal do some calculation if not do another calculation. I tired to group same element positions using transpose, then map the result and make comparison of current element with previous element in the list, I think the last part is where I am not clear.

EDIT:

Some more explanation, let say we have list like this

    List(List(i1, j1, k1), List(i2, j2, k2), List(in, jn, kn))

if i1 is equal to i2 then 1+i1+ i2*0.5 and j1 equal to j2 then 1+j1+j2*.0.5 and it goes upto kn and the second condition is if they are not equal i1 is not equal to i2 then it is a decrease, it will be i1+i2*0.5

hope this is explanation helps

Output I looking for 

List[Double] = List(2.5, 0.5, 0.5)

Upvotes: 0

Views: 744

Answers (3)

RAGHHURAAMM
RAGHHURAAMM

Reputation: 1099

lst.transpose.map(v=>if(v.forall(_==v.head)) v.sum*0.5+1 else v.sum*0.5))

or

lst.transpose.map(v=>if(v.exists(_!=v.head)) v.sum*0.5 else v.sum*0.5+1)

or

lst.transpose.map(v=>if(v.find(_!=v.head)!=None) v.sum*0.5 else v.sum*0.5+1)

These are in general, can be used for two different expressions to be evaluated for the two different cases ie., all elements equal or not equal in the lists after calling transpose function.ie.,

lst.transpose.map(v=>if(v.exists(_!=v.head)) 
                     (Expression1 in terms of elements in v) 
                     else (Expression2 in terms of elements in v) )

In Scala REPL: for,
val lst = List(List(1, 0, 0), List(1, 1, 0), List(1, 0, 1))

scala> lst.transpose.map(v=>if(v.forall(_==v.head)) v.sum*0.5+1 else v.sum*0.5)
res23: List[Double] = List(2.5, 0.5, 0.5)

scala> lst.transpose.map(v=>if(v.exists(_!=v.head)) v.sum*0.5 else v.sum*0.5+1)
res24: List[Double] = List(2.5, 0.5, 0.5)

scala> lst.transpose.map(v=>if(v.find(_!=v.head)!=None) v.sum*0.5 else v.sum*0.5+1)
res25: List[Double] = List(2.5, 0.5, 0.5)

Upvotes: 1

Sebastian Celestino
Sebastian Celestino

Reputation: 1428

You can use map and pattern matching

val list = List(List(1, 0, 0), List(1, 1, 0), List(1, 0, 1))

val result = list.transpose.map {
  case sublist if sublist.forall(sublist.head == _) => 1+0.5*sublist.sum
  case sublist => 0.5*sublist.sum
}

Upvotes: 0

jwvh
jwvh

Reputation: 51271

Your description is still very confusing but I think maybe something like this is what you're after.

val lst = List(List(1, 0, 0), List(1, 1, 0), List(1, 0, 1))

lst.transpose
   .map(sublst => sublst.sum*0.5 + (if (sublst.forall(_==sublst.head)) 1 else 0))
//res0: List[Double] = List(2.5, 0.5, 0.5)

If all the elements of the sub-list are the same, add 1 to the calculation, else add 0.

Upvotes: 1

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