double DCGCalculator::CalDCGAtK(data_size_t k, const label_t* label,
const double* score, data_size_t num_data) {
// get sorted indices by score
std::vector<data_size_t> sorted_idx(num_data);
for (data_size_t i = 0; i < num_data; ++i) {
sorted_idx[i] = i;
}
std::sort(sorted_idx.begin(), sorted_idx.end(),
[score](data_size_t a, data_size_t b) {return score[a] > score[b]; });
if (k > num_data) { k = num_data; }
double dcg = 0.0f;
// calculate dcg
for (data_size_t i = 0; i < k; ++i) {
data_size_t idx = sorted_idx[i];
dcg += label_gain_[static_cast<int>(label[idx])] * discount_[i];
}
return dcg;
}
void DCGCalculator::CalDCG(const std::vector<data_size_t>& ks, const label_t* label,
const double * score, data_size_t num_data, std::vector<double>* out) {
// get sorted indices by score
std::vector<data_size_t> sorted_idx(num_data);
for (data_size_t i = 0; i < num_data; ++i) {
sorted_idx[i] = i;
}
std::sort(sorted_idx.begin(), sorted_idx.end(),
[score](data_size_t a, data_size_t b) {return score[a] > score[b]; });
double cur_result = 0.0f;
data_size_t cur_left = 0;
// calculate multi dcg by one pass
for (size_t i = 0; i < ks.size(); ++i) {
data_size_t cur_k = ks[i];
if (cur_k > num_data) { cur_k = num_data; }
for (data_size_t j = cur_left; j < cur_k; ++j) {
data_size_t idx = sorted_idx[j];
cur_result += label_gain_[static_cast<int>(label[idx])] * discount_[j];
}
(*out)[i] = cur_result;
cur_left = cur_k;
}
}
//
// Get ranks and index of scores
//
// [[Rcpp::export]]
Rcpp::List get_score_ranks(const Rcpp::NumericVector& scores,
const bool& na_last,
const std::string& ties_method) {
// Variables
Rcpp::List ret_val;
std::string errmsg = "";
std::vector<int> ranks(scores.size());
std::vector<int> rank_idx(scores.size());
// Update NAs
std::vector<double> svals(scores.size());
std::vector<int> sorted_idx(scores.size());
for (int i = 0; i < scores.size(); ++i) {
if (Rcpp::NumericVector::is_na(scores[i])) {
if (na_last) {
svals[i] = DBL_MIN;
} else {
svals[i] = DBL_MAX;
}
} else {
svals[i] = scores[i];
}
sorted_idx[i] = i;
}
// Sort scores
CompDVec fcomp(svals);
if (ties_method == "first") {
std::stable_sort(sorted_idx.begin(), sorted_idx.end(), fcomp);
} else {
std::sort(sorted_idx.begin(), sorted_idx.end(), fcomp);
}
// Set ranks
for (unsigned i = 0; i < sorted_idx.size(); ++i) {
ranks[sorted_idx[i]] = i + 1;
rank_idx[i] = sorted_idx[i];
}
// Update ties
if (ties_method == "equiv" || ties_method == "random") {
std::vector<int> tied_idx;
double prev_val = svals[rank_idx[0]];
bool tied = false;
for (unsigned i = 1; i < rank_idx.size(); ++i) {
if (tied) {
if (prev_val != svals[rank_idx[i]]) {
update_ties(ranks, rank_idx, tied_idx, ties_method);
tied_idx.clear();
tied = false;
} else {
tied_idx.push_back(rank_idx[i]);
}
} else if (prev_val == svals[rank_idx[i]]) {
tied_idx.push_back(rank_idx[i - 1]);
tied_idx.push_back(rank_idx[i]);
tied = true;
}
prev_val = svals[rank_idx[i]];
}
if (tied) {
update_ties(ranks, rank_idx, tied_idx, ties_method);
}
}
// Add 1 to rank_idx
for (unsigned i = 0; i < rank_idx.size(); ++i) {
rank_idx[i] = rank_idx[i] + 1;
}
// Return result
ret_val["ranks"] = ranks;
ret_val["rank_idx"] = rank_idx;
ret_val["errmsg"] = errmsg;
return ret_val;
}