[MAHOUT-1959] BallKMeans.iterativeAssignment can set wrong weights.

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Fix Version/s: classic-15.0
• Assignee: Shashanka Balakuntala Srinivasa
• Reporter: Hao Zhong
• Created: 21/Mar/17 09:59
• Updated: 31/Jan/24 22:07

Description

I notice that the BallKMeans.iterativeAssignment method uses the following code to calculate weights:

BallKMeans.java

for (WeightedVector datapoint : datapoints) {
        Centroid closestCentroid = (Centroid) centroids.searchFirst(datapoint, false).getValue();
        closestCentroid.setWeight(closestCentroid.getWeight() + datapoint.getWeight());
      }

In MAHOUT-1237, the buggy code is the same way to calculate the weight:

ClusteringUtils.java

for (Vector vector : datapoints) {
      Centroid closest = (Centroid) centroids.searchFirst(vector, false).getValue();
      totalCost += closest.getWeight();
    }

The fixed code is as follow:

ClusteringUtils.java

for (Vector vector : datapoints) {
      totalCost += centroids.searchFirst(vector, false).getWeight();
    }

I am not quite sure whether BallKMeans.iterativeAssignment sets the right weights. Please check it.