void DataParallelTreeLearner<TREELEARNER_T>::FindBestSplitsFromHistograms(const std::vector<int8_t>&, bool) {
std::vector<SplitInfo> smaller_bests_per_thread(this->num_threads_, SplitInfo());
std::vector<SplitInfo> larger_bests_per_thread(this->num_threads_, SplitInfo());
OMP_INIT_EX();
#pragma omp parallel for schedule(static)
for (int feature_index = 0; feature_index < this->num_features_; ++feature_index) {
OMP_LOOP_EX_BEGIN();
if (!is_feature_aggregated_[feature_index]) continue;
const int tid = omp_get_thread_num();
const int real_feature_index = this->train_data_->RealFeatureIndex(feature_index);
// restore global histograms from buffer
this->smaller_leaf_histogram_array_[feature_index].FromMemory(
output_buffer_.data() + buffer_read_start_pos_[feature_index]);
this->train_data_->FixHistogram(feature_index,
this->smaller_leaf_splits_->sum_gradients(), this->smaller_leaf_splits_->sum_hessians(),
GetGlobalDataCountInLeaf(this->smaller_leaf_splits_->LeafIndex()),
this->smaller_leaf_histogram_array_[feature_index].RawData());
SplitInfo smaller_split;
// find best threshold for smaller child
this->smaller_leaf_histogram_array_[feature_index].FindBestThreshold(
this->smaller_leaf_splits_->sum_gradients(),
this->smaller_leaf_splits_->sum_hessians(),
GetGlobalDataCountInLeaf(this->smaller_leaf_splits_->LeafIndex()),
this->smaller_leaf_splits_->min_constraint(),
this->smaller_leaf_splits_->max_constraint(),
&smaller_split);
smaller_split.feature = real_feature_index;
if (smaller_split > smaller_bests_per_thread[tid]) {
smaller_bests_per_thread[tid] = smaller_split;
}
// only root leaf
if (this->larger_leaf_splits_ == nullptr || this->larger_leaf_splits_->LeafIndex() < 0) continue;
// construct histgroms for large leaf, we init larger leaf as the parent, so we can just subtract the smaller leaf's histograms
this->larger_leaf_histogram_array_[feature_index].Subtract(
this->smaller_leaf_histogram_array_[feature_index]);
SplitInfo larger_split;
// find best threshold for larger child
this->larger_leaf_histogram_array_[feature_index].FindBestThreshold(
this->larger_leaf_splits_->sum_gradients(),
this->larger_leaf_splits_->sum_hessians(),
GetGlobalDataCountInLeaf(this->larger_leaf_splits_->LeafIndex()),
this->larger_leaf_splits_->min_constraint(),
this->larger_leaf_splits_->max_constraint(),
&larger_split);
larger_split.feature = real_feature_index;
if (larger_split > larger_bests_per_thread[tid]) {
larger_bests_per_thread[tid] = larger_split;
}
OMP_LOOP_EX_END();
}
OMP_THROW_EX();
auto smaller_best_idx = ArrayArgs<SplitInfo>::ArgMax(smaller_bests_per_thread);
int leaf = this->smaller_leaf_splits_->LeafIndex();
this->best_split_per_leaf_[leaf] = smaller_bests_per_thread[smaller_best_idx];
if (this->larger_leaf_splits_ != nullptr && this->larger_leaf_splits_->LeafIndex() >= 0) {
leaf = this->larger_leaf_splits_->LeafIndex();
auto larger_best_idx = ArrayArgs<SplitInfo>::ArgMax(larger_bests_per_thread);
this->best_split_per_leaf_[leaf] = larger_bests_per_thread[larger_best_idx];
}
SplitInfo smaller_best_split, larger_best_split;
smaller_best_split = this->best_split_per_leaf_[this->smaller_leaf_splits_->LeafIndex()];
// find local best split for larger leaf
if (this->larger_leaf_splits_->LeafIndex() >= 0) {
larger_best_split = this->best_split_per_leaf_[this->larger_leaf_splits_->LeafIndex()];
}
// sync global best info
SyncUpGlobalBestSplit(input_buffer_.data(), input_buffer_.data(), &smaller_best_split, &larger_best_split, this->tree_config_->max_cat_threshold);
// set best split
this->best_split_per_leaf_[this->smaller_leaf_splits_->LeafIndex()] = smaller_best_split;
if (this->larger_leaf_splits_->LeafIndex() >= 0) {
this->best_split_per_leaf_[this->larger_leaf_splits_->LeafIndex()] = larger_best_split;
}
}
bool GBDT::LoadModelFromString(const char* buffer, size_t len) {
// use serialized string to restore this object
models_.clear();
auto c_str = buffer;
auto p = c_str;
auto end = p + len;
std::unordered_map<std::string, std::string> key_vals;
while (p < end) {
auto line_len = Common::GetLine(p);
std::string cur_line(p, line_len);
if (line_len > 0) {
if (!Common::StartsWith(cur_line, "Tree=")) {
auto strs = Common::Split(cur_line.c_str(), '=');
if (strs.size() == 1) {
key_vals[strs[0]] = "";
}
else if (strs.size() == 2) {
key_vals[strs[0]] = strs[1];
}
else if (strs.size() > 2) {
if (strs[0] == "feature_names") {
key_vals[strs[0]] = cur_line.substr(std::strlen("feature_names="));
} else {
// Use first 128 chars to avoid exceed the message buffer.
Log::Fatal("Wrong line at model file: %s", cur_line.substr(0, std::min<size_t>(128, cur_line.size())).c_str());
}
}
}
else {
break;
}
}
p += line_len;
p = Common::SkipNewLine(p);
}
// get number of classes
if (key_vals.count("num_class")) {
Common::Atoi(key_vals["num_class"].c_str(), &num_class_);
} else {
Log::Fatal("Model file doesn't specify the number of classes");
return false;
}
if (key_vals.count("num_tree_per_iteration")) {
Common::Atoi(key_vals["num_tree_per_iteration"].c_str(), &num_tree_per_iteration_);
} else {
num_tree_per_iteration_ = num_class_;
}
// get index of label
if (key_vals.count("label_index")) {
Common::Atoi(key_vals["label_index"].c_str(), &label_idx_);
} else {
Log::Fatal("Model file doesn't specify the label index");
return false;
}
// get max_feature_idx first
if (key_vals.count("max_feature_idx")) {
Common::Atoi(key_vals["max_feature_idx"].c_str(), &max_feature_idx_);
} else {
Log::Fatal("Model file doesn't specify max_feature_idx");
return false;
}
// get average_output
if (key_vals.count("average_output")) {
average_output_ = true;
}
// get feature names
if (key_vals.count("feature_names")) {
feature_names_ = Common::Split(key_vals["feature_names"].c_str(), ' ');
if (feature_names_.size() != static_cast<size_t>(max_feature_idx_ + 1)) {
Log::Fatal("Wrong size of feature_names");
return false;
}
} else {
Log::Fatal("Model file doesn't contain feature_names");
return false;
}
if (key_vals.count("feature_infos")) {
feature_infos_ = Common::Split(key_vals["feature_infos"].c_str(), ' ');
if (feature_infos_.size() != static_cast<size_t>(max_feature_idx_ + 1)) {
Log::Fatal("Wrong size of feature_infos");
return false;
}
} else {
Log::Fatal("Model file doesn't contain feature_infos");
return false;
}
if (key_vals.count("objective")) {
auto str = key_vals["objective"];
loaded_objective_.reset(ObjectiveFunction::CreateObjectiveFunction(str));
objective_function_ = loaded_objective_.get();
}
if (!key_vals.count("tree_sizes")) {
while (p < end) {
auto line_len = Common::GetLine(p);
std::string cur_line(p, line_len);
if (line_len > 0) {
if (Common::StartsWith(cur_line, "Tree=")) {
p += line_len;
p = Common::SkipNewLine(p);
size_t used_len = 0;
models_.emplace_back(new Tree(p, &used_len));
p += used_len;
}
else {
break;
}
}
p = Common::SkipNewLine(p);
}
} else {
std::vector<size_t> tree_sizes = Common::StringToArray<size_t>(key_vals["tree_sizes"].c_str(), ' ');
std::vector<size_t> tree_boundries(tree_sizes.size() + 1, 0);
int num_trees = static_cast<int>(tree_sizes.size());
for (int i = 0; i < num_trees; ++i) {
tree_boundries[i + 1] = tree_boundries[i] + tree_sizes[i];
models_.emplace_back(nullptr);
}
OMP_INIT_EX();
#pragma omp parallel for schedule(static)
for (int i = 0; i < num_trees; ++i) {
OMP_LOOP_EX_BEGIN();
auto cur_p = p + tree_boundries[i];
auto line_len = Common::GetLine(cur_p);
std::string cur_line(cur_p, line_len);
if (Common::StartsWith(cur_line, "Tree=")) {
cur_p += line_len;
cur_p = Common::SkipNewLine(cur_p);
size_t used_len = 0;
models_[i].reset(new Tree(cur_p, &used_len));
} else {
Log::Fatal("Model format error, expect a tree here. met %s", cur_line.c_str());
}
OMP_LOOP_EX_END();
}
OMP_THROW_EX();
}
num_iteration_for_pred_ = static_cast<int>(models_.size()) / num_tree_per_iteration_;
num_init_iteration_ = num_iteration_for_pred_;
iter_ = 0;
return true;
}