I have a list of tuples called item, each index in the list contains 2 x Doubles e.g.
item = ((1.0, 2.0), (3.0, 4.0), (10.0, 100.0))
I want to perform a calculation on each index within the list item and I'm trying to do it with foldLeft. This is my code:
item.foldLeft(0.0)(_ + myMethod(_._2, _._1, item.size)))
_._2 accesses the current item Tuple at index 1 and _._1 accesses the current item Tuple at index 0. e.g. for the first fold it should effectively be:
item.foldLeft(0.0)(_ + myMethod(2.0, 1.0, item.size)))
The Second Fold:
item.foldLeft(0.0)(_ + myMethod(4.0, 3.0, item.size)))
The Third Fold:
item.foldLeft(0.0)(_ + myMethod(100.0, 10.0, item.size)))
where myMethod:
def myMethod(i: Double, j:Double, size: Integer) : Double = {
(j - i) / size
}
It is giving me an error which says that there are too many parameters for foldLeft as it requires 2 parameters.
myMethod returns a Double, and _ is a Double. So, where is this extra parameter the compiler is seeing?
If I do this:
item.foldLeft(0.0)(_ + _._1))
It sums up all the first Doubles in each index of item - replacing _._1 with _._2 sums up all the second Doubles in each index of item.
Any help is greatly appreciated!
Each _ is equivalent to a new argument, so (_ + myMethod(_._2, _._1, item.size)) is an anonymous function with 3 arguments: (x, y, z) => x + myMethod(y._2, z._1, item.size).
What you want is (acc, x) => acc + myMethod(x._2, x._1, item.size).