'Multidimensional Array zip array in scala

I have two array like:

val one = Array(1, 2, 3, 4)
val two = Array(4, 5, 6, 7)
var three = one zip two map{case(a, b) => a * b}

It's ok.

But I have a multidimensional Array and a one-dimensional array now, like this:

val mulOne = Array(Array(1, 2, 3, 4),Array(5, 6, 7, 8),Array(9, 10, 11, 12))
val one_arr = Array(1, 2, 3, 4)

I would like to multiplication them, how can I do this in scala?

arraysscala


Solution 1:[1]

You could use:

val tmpArr = mulOne.map(_ zip one_arr).map(_.map{case(a,b) => a*b})

This would give you Array(Array(1*1, 2*2, 3*3, 4*4), Array(5*1, 6*2, 7*3, 8*4), Array(9*1, 10*2, 11*3, 12*4)).

Here mulOne.map(_ zip one_arr) maps each internal array of mulOne with corresponding element of one_arr to create pairs like: Array(Array((1,1), (2,2), (3,3), (4,4)), ..) (Note: I have used placeholder syntax). In the next step .map(_.map{case(a,b) => a*b}) multiplies each elements of pair to give output like: Array(Array(1, 4, 9, 16),..)

Then you could use:

tmpArr.map(_.reduce(_ + _))

to get sum of all internal Arrays to get Array(30, 70, 110)

Solution 2:[2]

Try this 

mulOne.map{x => (x, one_arr)}.map { case(one, two) => one zip two map{case(a, b) => a * b} }

mulOne.map{x => (x, one_arr)} => for every array inside mulOne, create a tuple with content of one_arr.

.map { case(one, two) => one zip two map{case(a, b) => a * b} } is basically the operation that you performed in your first example on every tuple that were created in the first step.

Solution 3:[3]

Using a for comprehension like this,

val prods = 
  for { xs <- mulOne
       zx = one_arr zip xs
       (a,b) <- zx
      } yield a*b

and so

prods.sum

delivers the final result.

Sources

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Source: Stack Overflow

Solution Source
Solution 1
Solution 2 mohit
Solution 3 elm

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