double ThresholdCurve::getNPointPrecision(Instances &tcurve, const int n) {
if (RELATION_NAME != tcurve.getRelationName() || (tcurve.numInstances() == 0)) {
return std::numeric_limits<double>::quiet_NaN();
}
int recallInd = tcurve.attribute(RECALL_NAME).index();
int precisInd = tcurve.attribute(PRECISION_NAME).index();
double_array recallVals = tcurve.attributeToDoubleArray(recallInd);
int_array sorted = Utils::Sort(recallVals);
double isize = 1.0 / (n - 1);
double psum = 0;
for (int i = 0; i < n; i++) {
int pos = binarySearch(sorted, recallVals, i * isize);
double recall = recallVals[sorted[pos]];
double precis = tcurve.instance(sorted[pos]).value(precisInd);
// interpolate figures for non-endpoints
while ((pos != 0) && (pos < sorted.size() - 1)) {
pos++;
double recall2 = recallVals[sorted[pos]];
if (recall2 != recall) {
double precis2 = tcurve.instance(sorted[pos]).value(precisInd);
double slope = (precis2 - precis) / (recall2 - recall);
double offset = precis - recall * slope;
precis = isize * i * slope + offset;
break;
}
}
psum += precis;
}
return psum / n;
}
void Instances::copyInstances(const int from, const Instances &dest, const int num)
{
for (int i = 0; i < num; i++)
{
Instance *newInstance = new Instance(dest.instance(i).weight(), dest.instance(i).toDoubleArray());
newInstance->setDataset(const_cast<Instances*>(this));
mInstances.push_back(newInstance);
}
}
