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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "gbdt.h"
#include "vm_forest.h"
#include "node_traverser.h"
#include <vespa/eval/eval/basic_nodes.h>
#include <vespa/eval/eval/call_nodes.h>
#include <vespa/eval/eval/operator_nodes.h>
namespace vespalib {
namespace eval {
namespace gbdt {
//-----------------------------------------------------------------------------
std::vector<const nodes::Node *> extract_trees(const nodes::Node &node) {
std::vector<const nodes::Node *> trees;
std::vector<const nodes::Node *> todo;
if (node.is_tree()) {
trees.push_back(&node);
} else if (node.is_forest()) {
todo.push_back(&node);
}
while (!todo.empty()) {
const nodes::Node &forest = *todo.back(); todo.pop_back();
for (size_t i = 0; i < forest.num_children(); ++i) {
const nodes::Node &child = forest.get_child(i);
if (child.is_tree()) {
trees.push_back(&child);
} else if (child.is_forest()) {
todo.push_back(&child);
}
}
}
return trees;
}
//-----------------------------------------------------------------------------
TreeStats::TreeStats(const nodes::Node &tree)
: size(0),
num_less_checks(0),
num_in_checks(0),
num_inverted_checks(0),
num_tuned_checks(0),
max_set_size(0),
expected_path_length(0.0),
average_path_length(0.0),
num_params(0)
{
size_t sum_path = 0.0;
expected_path_length = traverse(tree, 0, sum_path);
average_path_length = double(sum_path) / double(size);
}
double
TreeStats::traverse(const nodes::Node &node, size_t depth, size_t &sum_path) {
if (auto if_node = nodes::as<nodes::If>(node)) {
double p_true = if_node->p_true();
if (p_true != 0.5) {
++num_tuned_checks;
}
double true_path = traverse(if_node->true_expr(), depth + 1, sum_path);
double false_path = traverse(if_node->false_expr(), depth + 1, sum_path);
auto less = nodes::as<nodes::Less>(if_node->cond());
auto in = nodes::as<nodes::In>(if_node->cond());
auto inverted = nodes::as<nodes::Not>(if_node->cond());
if (less) {
auto symbol = nodes::as<nodes::Symbol>(less->lhs());
assert(symbol);
num_params = std::max(num_params, size_t(symbol->id() + 1));
++num_less_checks;
} else if (in) {
auto symbol = nodes::as<nodes::Symbol>(in->child());
assert(symbol);
num_params = std::max(num_params, size_t(symbol->id() + 1));
++num_in_checks;
max_set_size = std::max(max_set_size, in->num_entries());
} else {
assert(inverted);
auto ge = nodes::as<nodes::GreaterEqual>(inverted->child());
assert(ge);
auto symbol = nodes::as<nodes::Symbol>(ge->lhs());
assert(symbol);
num_params = std::max(num_params, size_t(symbol->id() + 1));
++num_inverted_checks;
}
return 1.0 + (p_true * true_path) + ((1.0 - p_true) * false_path);
} else {
++size;
sum_path += depth;
return 0.0;
}
}
ForestStats::ForestStats(const std::vector<const nodes::Node *> &trees)
: num_trees(trees.size()),
total_size(0),
tree_sizes(),
total_less_checks(0),
total_in_checks(0),
total_inverted_checks(0),
total_tuned_checks(0),
max_set_size(0),
total_expected_path_length(0.0),
total_average_path_length(0.0),
num_params(0)
{
std::map<size_t,size_t> size_map;
for (const nodes::Node *tree: trees) {
TreeStats stats(*tree);
num_params = std::max(num_params, stats.num_params);
total_size += stats.size;
++size_map[stats.size];
total_less_checks += stats.num_less_checks;
total_in_checks += stats.num_in_checks;
total_inverted_checks += stats.num_inverted_checks;
total_tuned_checks += stats.num_tuned_checks;
max_set_size = std::max(max_set_size, stats.max_set_size);
total_expected_path_length += stats.expected_path_length;
total_average_path_length += stats.average_path_length;
}
for (auto const &size: size_map) {
tree_sizes.push_back(TreeSize{size.first, size.second});
}
}
//-----------------------------------------------------------------------------
bool contains_gbdt(const nodes::Node &node, size_t limit) {
struct FindGBDT : NodeTraverser {
size_t seen;
size_t limit;
explicit FindGBDT(size_t limit_in) : seen(0), limit(limit_in) {}
bool found() const { return (seen >= limit); }
bool open(const nodes::Node &) override { return !found(); }
void close(const nodes::Node &node) override {
if (node.is_tree() || node.is_forest()) {
++seen;
}
}
} findGBDT(limit);
node.traverse(findGBDT);
return findGBDT.found();
}
//-----------------------------------------------------------------------------
Optimize::Result
Optimize::select_best(const ForestStats &stats,
const std::vector<const nodes::Node *> &trees)
{
double path_len = stats.total_average_path_length;
if ((stats.tree_sizes.back().size > 12) && (path_len > 2500.0)) {
return apply_chain(VMForest::optimize_chain, stats, trees);
}
return Optimize::Result();
}
Optimize::Chain Optimize::best({select_best});
Optimize::Chain Optimize::none;
//-----------------------------------------------------------------------------
} // namespace vespalib::eval::gbdt
} // namespace vespalib::eval
} // namespace vespalib
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