/**
* Computes for each object the distance to one reference point. (one dimensional representation
* of the data set)
*
* @param refPoint Reference Point Feature Vector
* @param database database to work on
* @param distFunc Distance function to use
* @return array containing the distance to one reference point for each database object and the
* object id
*/
protected DoubleDBIDList computeDistanceVector(
NumberVector refPoint,
Relation<? extends NumberVector> database,
PrimitiveDistanceQuery<? super NumberVector> distFunc) {
ModifiableDoubleDBIDList referenceDists = DBIDUtil.newDistanceDBIDList(database.size());
for (DBIDIter iditer = database.iterDBIDs(); iditer.valid(); iditer.advance()) {
referenceDists.add(distFunc.distance(iditer, refPoint), iditer);
}
referenceDists.sort();
return referenceDists;
}
/**
* Refine a range query.
*
* @param neighc Original result
* @param adjustedEps New epsilon
* @return refined list
*/
private DoubleDBIDList refineRange(DoubleDBIDList neighc, double adjustedEps) {
ModifiableDoubleDBIDList n = DBIDUtil.newDistanceDBIDList(neighc.size());
// We don't have a guarantee for this list to be sorted
for (DoubleDBIDListIter neighbor = neighc.iter(); neighbor.valid(); neighbor.advance()) {
DoubleDBIDPair p = neighbor.getPair();
double dist = p.doubleValue();
if (dist <= adjustedEps) {
n.add(dist, p);
}
}
return n;
}
/**
* Refine neighbors within a subset.
*
* @param neighc Neighbor candidates
* @param dbid Query object
* @param df distance function
* @param adjustedEps Epsilon range
* @param kernel Kernel
* @return Neighbors of neighbor object
*/
private DoubleDBIDList subsetNeighborhoodQuery(
DoubleDBIDList neighc,
DBIDRef dbid,
PrimitiveDistanceFunction<? super V> df,
double adjustedEps,
KernelDensityEstimator kernel) {
ModifiableDoubleDBIDList n = DBIDUtil.newDistanceDBIDList(neighc.size());
V query = kernel.relation.get(dbid);
for (DoubleDBIDListIter neighbor = neighc.iter(); neighbor.valid(); neighbor.advance()) {
DoubleDBIDPair p = neighbor.getPair();
double dist = df.distance(query, kernel.relation.get(p));
if (dist <= adjustedEps) {
n.add(dist, p);
}
}
return n;
}