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lambda rank added

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This commit is contained in:
kalenhaha
2014-04-10 22:09:19 +08:00
parent a10f594644
commit c8b2f46b89
18 changed files with 1792 additions and 76 deletions
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184
dev/rank/xgboost_rank.h
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@@ -7,7 +7,7 @@
*/
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <vector>
#include "xgboost_sample.h"
#include "xgboost_rank_eval.h"
#include "../base/xgboost_data_instance.h"
@@ -71,11 +71,139 @@ namespace xgboost {
fprintf(fo, "\n");
}
inline void SetParam(const char *name, const char *val){
if (!strcmp(name, "eval_metric")) evaluator_.AddEval(val);
virtual inline void SetParam(const char *name, const char *val){
BoostLearner::SetParam(name,val);
if (!strcmp(name, "eval_metric")) evaluator_.AddEval(val);
if (!strcmp(name, "rank:sampler")) sampler.AssignSampler(atoi(val));
}
/*! \brief get the first order and second order gradient, given the transformed predictions and labels */
private:
inline std::vector< Triple<float,float,int> > GetSortedTuple(const std::vector<float> &preds,
const std::vector<float> &labels,
const std::vector<int> &group_index,
int group){
std::vector< Triple<float,float,int> > sorted_triple;
for(int j = group_index[group]; j < group_index[group+1]; j++){
sorted_triple.push_back(Triple<float,float,int>(preds[j],labels[j],j));
}
std::sort(sorted_triple.begin(),sorted_triple.end(),Triplef1Comparer);
return sorted_triple;
}
inline std::vector<int> GetIndexMap(std::vector< Triple<float,float,int> > sorted_triple,int start){
std::vector<int> index_remap;
index_remap.resize(sorted_triple.size());
for(int i = 0; i < sorted_triple.size(); i++){
index_remap[sorted_triple[i].f3_-start] = i;
}
return index_remap;
}
inline float GetLambdaMAP(const std::vector< Triple<float,float,int> > sorted_triple,
int index1,int index2,
std::vector< Quadruple<float,float,float,float> > map_acc){
if(index1 > index2) std::swap(index1,index2);
float original = map_acc[index2].f1_;
if(index1 != 0) original -= map_acc[index1 - 1].f1_;
float changed = 0;
if(sorted_triple[index1].f2_ < sorted_triple[index2].f2_){
changed += map_acc[index2 - 1].f3_ - map_acc[index1].f3_;
changed += (map_acc[index1].f4_ + 1.0f)/(index1 + 1);
}else{
changed += map_acc[index2 - 1].f2_ - map_acc[index1].f2_;
changed += map_acc[index2].f4_/(index2 + 1);
}
float ans = (changed - original)/(map_acc[map_acc.size() - 1].f4_);
if(ans < 0) ans = -ans;
return ans;
}
inline float GetLambdaNDCG(const std::vector< Triple<float,float,int> > sorted_triple,
int index1,
int index2,float IDCG){
float original = pow(2,sorted_triple[index1].f2_)/log(index1+2)
+ pow(2,sorted_triple[index2].f2_)/log(index2+2);
float changed = pow(2,sorted_triple[index2].f2_)/log(index1+2)
+ pow(2,sorted_triple[index1].f2_)/log(index2+2);
float ans = (original - changed)/IDCG;
if(ans < 0) ans = -ans;
return ans;
}
inline float GetIDCG(const std::vector< Triple<float,float,int> > sorted_triple){
std::vector<float> labels;
for(int i = 0; i < sorted_triple.size(); i++){
labels.push_back(sorted_triple[i].f2_);
}
std::sort(labels.begin(),labels.end(),std::greater<float>());
return EvalNDCG::DCG(labels);
}
inline std::vector< Quadruple<float,float,float,float> > GetMAPAcc(const std::vector< Triple<float,float,int> > sorted_triple){
std::vector< Quadruple<float,float,float,float> > map_acc;
float hit = 0,acc1 = 0,acc2 = 0,acc3 = 0;
for(int i = 0; i < sorted_triple.size(); i++){
if(sorted_triple[i].f2_ == 1) {
hit++;
acc1 += hit /( i + 1 );
acc2 += (hit - 1)/(i+1);
acc3 += (hit + 1)/(i+1);
}
map_acc.push_back(Quadruple<float,float,float,float>(acc1,acc2,acc3,hit));
}
return map_acc;
}
inline void GetGroupGradient(const std::vector<float> &preds,
const std::vector<float> &labels,
const std::vector<int> &group_index,
std::vector<float> &grad,
std::vector<float> &hess,
const std::vector< Triple<float,float,int> > sorted_triple,
const std::vector<int> index_remap,
const sample::Pairs& pairs,
int group){
bool j_better;
float IDCG, pred_diff, pred_diff_exp, delta;
float first_order_gradient, second_order_gradient;
std::vector< Quadruple<float,float,float,float> > map_acc;
if(mparam.loss_type == NDCG){
IDCG = GetIDCG(sorted_triple);
}else if(mparam.loss_type == MAP){
map_acc = GetMAPAcc(sorted_triple);
}
for (int j = group_index[group]; j < group_index[group + 1]; j++){
std::vector<int> pair_instance = pairs.GetPairs(j);
for (int k = 0; k < pair_instance.size(); k++){
j_better = labels[j] > labels[pair_instance[k]];
if (j_better){
switch(mparam.loss_type){
case PAIRWISE: delta = 1.0;break;
case MAP: delta = GetLambdaMAP(sorted_triple,index_remap[j - group_index[group]],index_remap[pair_instance[k]-group_index[group]],map_acc);break;
case NDCG: delta = GetLambdaNDCG(sorted_triple,index_remap[j - group_index[group]],index_remap[pair_instance[k]-group_index[group]],IDCG);break;
default: utils::Error("Cannot find the specified loss type");
}
pred_diff = preds[preds[j] - pair_instance[k]];
pred_diff_exp = j_better ? expf(-pred_diff) : expf(pred_diff);
first_order_gradient = delta * FirstOrderGradient(pred_diff_exp);
second_order_gradient = 2 * delta * SecondOrderGradient(pred_diff_exp);
hess[j] += second_order_gradient;
grad[j] += first_order_gradient;
hess[pair_instance[k]] += second_order_gradient;
grad[pair_instance[k]] += -first_order_gradient;
}
}
}
}
public:
/*! \brief get the first order and second order gradient, given the
* intransformed predictions and labels */
inline void GetGradient(const std::vector<float> &preds,
const std::vector<float> &labels,
const std::vector<int> &group_index,
@@ -83,32 +211,44 @@ namespace xgboost {
std::vector<float> &hess) {
grad.resize(preds.size());
hess.resize(preds.size());
bool j_better;
float pred_diff, pred_diff_exp, first_order_gradient, second_order_gradient;
for (int i = 0; i < group_index.size() - 1; i++){
sample::Pairs pairs = sampler.GenPairs(preds, labels, group_index[i], group_index[i + 1]);
for (int j = group_index[i]; j < group_index[i + 1]; j++){
std::vector<int> pair_instance = pairs.GetPairs(j);
for (int k = 0; k < pair_instance.size(); k++){
j_better = labels[j] > labels[pair_instance[k]];
if (j_better){
pred_diff = preds[preds[j] - pair_instance[k]];
pred_diff_exp = j_better ? expf(-pred_diff) : expf(pred_diff);
first_order_gradient = FirstOrderGradient(pred_diff_exp);
second_order_gradient = 2 * SecondOrderGradient(pred_diff_exp);
hess[j] += second_order_gradient;
grad[j] += first_order_gradient;
hess[pair_instance[k]] += second_order_gradient;
grad[pair_instance[k]] += -first_order_gradient;
}
}
}
//pairs.GetPairs()
std::vector< Triple<float,float,int> > sorted_triple = GetSortedTuple(preds,labels,group_index,i);
std::vector<int> index_remap = GetIndexMap(sorted_triple,group_index[i]);
GetGroupGradient(preds,labels,group_index,
grad,hess,sorted_triple,index_remap,pairs,i);
}
}
inline void UpdateInteract(std::string action) {
this->InteractPredict(preds_, *train_, 0);
int buffer_offset = static_cast<int>(train_->Size());
for (size_t i = 0; i < evals_.size(); ++i){
std::vector<float> &preds = this->eval_preds_[i];
this->InteractPredict(preds, *evals_[i], buffer_offset);
buffer_offset += static_cast<int>(evals_[i]->Size());
}
if (action == "remove"){
base_gbm.DelteBooster(); return;
}
this->GetGradient(preds_, train_->labels,train_->group_index, grad_, hess_);
std::vector<unsigned> root_index;
base_gbm.DoBoost(grad_, hess_, train_->data, root_index);
this->InteractRePredict(*train_, 0);
buffer_offset = static_cast<int>(train_->Size());
for (size_t i = 0; i < evals_.size(); ++i){
this->InteractRePredict(*evals_[i], buffer_offset);
buffer_offset += static_cast<int>(evals_[i]->Size());
}
}
private:
enum LossType {
PAIRWISE = 0,