Scala Spark中两个数组之间的交叉产品

Question

考虑scala-spark中的两个数组

val mole_1 = Array(2.0,1.0,0.0,0.0,0.0,0.0)
val mole_2 = Array(2.0,2.0,0.0,0.0,0.0,0.0)

现在，两个数组的元素乘法的有效方法是

val dot_Mole = (mole_1, mole_2).zipped.map(_ * _).sum

Which yields  >> 6.0

如何使用zipped和map来实现这些数组之间的交叉产品，以提供＆gt;＆gt; 12.0？

仅使用zipped, map and reduce。

Answer 1

你可以这样做：

val dot_mole = Mole_1.map{ x => Mole_2.map(b => b * x)}.flatten.sum
dot_mole: Double = 12.0