/* compute the information needed to update the current context stats. */
void SkipCTS::getContextInfo(zobhash_t &hash, const indices_t &idxs) const {
// compute the hash
for (int k=0; k < idxs.size(); k++) {
size_t x = idxs[k];
hash ^= s_zobtbl[x][m_context[x]];
}
}
void tuner_t::map(const indices_t& indices, strings_t& values) const
{
assert(indices.size() == m_params.size());
assert(values.size() == m_params.size());
for (size_t i = 0; i < m_params.size(); ++ i)
{
const auto& param = m_params[i];
assert(indices[i] < param.m_values.size());
values[i] = param.m_values[indices[i]];
}
}
int WeakDiscreteTreeLearner::findThreshold(
const weights_t &weights,
const indices_t & sortedIndices,
const size_t featureIndex,
double &errorMin, int &thresholdMin, int &alphaMin, int &splitIndex) const
{
const FeaturesResponses &featuresResponses = _trainingData->getFeatureResponses();
const FeaturesResponses::const_reference featureResponses = featuresResponses[featureIndex];
//getSum of data
double sumPos = 0;
double sumNeg = 0;
errorMin = std::numeric_limits<int>::max();
for (size_t i = 0; i < sortedIndices.size(); ++i)
{
const int index = sortedIndices[i];
if (_classes[index] == _negativeClass)
{
sumNeg += weights[index];
}
else
{
sumPos += weights[index];
}
}
if (_verbose > 3)
{
std::cout << "sumneg: " << sumNeg << " sumpos: " << sumPos << " both: " << sumPos + sumNeg << "\n";
}
if (sumNeg == 0)
{
thresholdMin = featureResponses[sortedIndices[0]] - 1;
alphaMin = -1;
errorMin = 0;
return -1;
}
if (sumPos == 0)
{
thresholdMin = featureResponses[sortedIndices[0]] - 1;
alphaMin = 1;
errorMin = 0;
return -1;
}
//positives left
double positiveLeftError = sumPos;
double negativeLeftError = 0;
//positives right
double negativeRightError = sumNeg;
double positiveRightError = 0;
int minIndex = -1;
// go over all sorted data elements
for (size_t i = 0; i < sortedIndices.size(); ++i)
{
const int index = sortedIndices[i];
const int threshold = featureResponses[index];
if (_classes[index] == _negativeClass)
{
negativeLeftError += weights[index];
negativeRightError -= weights[index];
}
else
{
positiveLeftError -= weights[index];
positiveRightError += weights[index];
}
double error = 0;
int alpha = 0;
if (positiveLeftError + negativeLeftError < positiveRightError + negativeRightError)
{
alpha = 1;
error = positiveLeftError + negativeLeftError;
}
else
{
alpha = -1;
error = positiveRightError + negativeRightError;
}
bool cond = false;
if (i < sortedIndices.size() - 1)
{
cond = (error < errorMin && threshold != featureResponses[sortedIndices[i+1]]);
}
else
{
cond = (error < errorMin) ;
}
if (cond)
{
errorMin = error;
thresholdMin = threshold;
alphaMin = alpha;
minIndex = i;
splitIndex = i + 1;
}
}// end of "for each sorted data element"
//set the threshold between suceeding values, except the last one(+1)
if (minIndex == int(sortedIndices.size() - 1))
{
thresholdMin = thresholdMin + 1;
}
else if (thresholdMin + 1 == featureResponses[sortedIndices[minIndex+1]])
{
thresholdMin = thresholdMin + 1;
}
else
{
thresholdMin = int((featureResponses[sortedIndices[minIndex]] + featureResponses[sortedIndices[minIndex+1]]) / 2.0);
}
if (_verbose > 3)
{
std::cout << "sorted data:\n";
for (size_t i = 0; i < sortedIndices.size(); ++i)
{
const int index = sortedIndices[i];
const int threshold = featureResponses[index];
std::cout << std::setw(6) << threshold << " ";
}
std::cout << "sorted classes:\n";
for (size_t i = 0; i < sortedIndices.size(); ++i)
{
int ind = sortedIndices[i];
std::cout << std::setprecision(2) << std::setw(6) << _classes[ind]*weights[ind] << " ";
}
std::cout << "threshold: " << thresholdMin << " alpha: " << alphaMin << " error: " << errorMin;
}
return 0;
}
inline
int WeakDiscreteTreeLearner::getErrorEstimate(
const weights_t &weights,
const indices_t& indices, const size_t featureIndex,
int num_bins , const int minv, const int maxv, double &error) const
{
if ((maxv - minv) < num_bins)
{
num_bins = maxv - minv;
}
//std::cout << "binsize: " << binsize << std::endl;
std::vector<double> bin_pos(num_bins + 1, 0), bin_neg(num_bins + 1, 0);
double cumNeg = 0;
double cumPos = 0;
error = std::numeric_limits<double>::max();
const FeaturesResponses &featuresResponses = _trainingData->getFeatureResponses();
for (size_t i = 0; i < indices.size(); ++i)
{
const size_t trainingSampleIndex = indices[i];
//FIXME CHECK this
//if (weights[trainingSampleIndex]< 1E-12)
// continue;
const int featureResponse = featuresResponses[featureIndex][trainingSampleIndex];
const int bin = int(num_bins / double(maxv - minv) * (featureResponse - minv));
//int splitpos = minv + (bin/(double)binsize) *(maxv-minv);
//int bin2= binsize/maxv*((*_featureResp)[pos+ind[i]] - minv);
//assert(bin==bin2);
const int the_class = _classes[indices[i]];
if (the_class == _negativeClass)
{
bin_neg[bin] += weights[indices[i]];
cumNeg += weights[indices[i]];
}
else
{
bin_pos[bin] += weights[indices[i]];
cumPos += weights[indices[i]];
}
}
//run test by setting this to return 0 with error 0
if (cumPos == 0 || cumNeg == 0)
{
return -1;
}
double
//positives left
positivesLeftError = cumPos,
negativesLeftError = 0,
//positives right
negativesRightError = cumNeg,
positivesRightError = 0;
//int minbin = -1;
for (int i = 0; i < num_bins; ++i)
{
positivesLeftError -= bin_pos[i];
negativesLeftError += bin_neg[i];
positivesRightError += bin_pos[i];
negativesRightError -= bin_neg[i];
double binError = 0;
if (positivesLeftError + negativesLeftError < positivesRightError + negativesRightError)
{
binError = positivesLeftError + negativesLeftError;
}
else
{
binError = positivesRightError + negativesRightError;
}
// we keep the min error
if (binError < error)
{
//minbin = i;
error = binError;
}
}
return 0;
}
