Github user viirya commented on a diff in the pull request:
https://github.com/apache/spark/pull/3643#discussion_r21663352
--- Diff: mllib/src/main/scala/org/apache/spark/mllib/util/MLUtils.scala ---
@@ -264,6 +263,60 @@ object MLUtils {
}
Vectors.fromBreeze(vector1)
}
+
+ /**
+ * Returns the squared distance between two Vectors.
+ */
+ def vectorSquaredDistance(v1: Vector, v2: Vector): Double = {
+ var squaredDistance = 0.0
+ (v1, v2) match {
+ case (v1: SparseVector, v2: SparseVector) =>
+ v1.indices.intersect(v2.indices).foreach((idx) => {
--- End diff --
Hi, thanks, but I do not really understand your idea. The indices array in
`SparseVector` only keeps the dimensions that have values in that
`SparseVector`. BLAS.dot is used to calculate dot product between two vectors.
How we use it to compute the intersection between two indices arrays? For
example, vector1's indices is `[1, 5, 10]` and vector2's indices is `[5, 6,
7]`. The dot product between them is 1 * 5 + 5 * 6 + 10 * 7 = 105. But it is
useless for computing the intersection.
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