How to get the exact nearest neighbors?

[hexiaoyupku]

Hi,
The code commets said that we could get the exact nearest neighbors by tuning parameters. But I haven't figured out how to do it.
I tried to set tau to 0.0, but didn't get the exact result. I think the reason is that KNN.searchIndices of the topTree doesn't always return all the possible partition ids which contains nearest neighbors.
Of course, I could rewrite the KNN.searchIndices to make sure all possible partition ids are included. But I still want to know if there is a way to get exact nearest neighbors by just tuning parameters in the existing code.

Thanks!

[hexiaoyupku]

I figured out a way to produce exact top k neareast neighbors without changing any code:

val model = new KNN()
.setBalanceThreshold(0.0)
.setFeaturesCol(featuresCol)
.fit(trainData)

val predictData = model
.setBufferSize(Double.MaxValue)
.setDistanceCol(distanceCol)
.setNeighborsCol(neighborsCol)
.setK(k)
.transform(testData)