- ndcg ltr implementation on gpu (#5004)

* - ndcg ltr implementation on gpu - this is a follow-up to the pairwise ltr implementation
dmlc · Nov 12, 2019 · 2abe69d · 2abe69d
1 parent f4e7b70
commit 2abe69d
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Showing 5 changed files with 778 additions and 200 deletions.
diff --git a/src/metric/rank_metric.cc b/src/metric/rank_metric.cc
@@ -98,7 +98,7 @@ struct EvalAMS : public Metric {
     for (bst_omp_uint i = 0; i < ndata; ++i) {
       rec[i] = std::make_pair(h_preds[i], i);
     }
-    std::sort(rec.begin(), rec.end(), common::CmpFirst);
+    std::stable_sort(rec.begin(), rec.end(), common::CmpFirst);
     auto ntop = static_cast<unsigned>(ratio_ * ndata);
     if (ntop == 0) ntop = ndata;
     const double br = 10.0;
@@ -168,7 +168,7 @@ struct EvalAuc : public Metric {
       for (unsigned j = gptr[group_id]; j < gptr[group_id + 1]; ++j) {
         rec.emplace_back(h_preds[j], j);
       }
-      XGBOOST_PARALLEL_SORT(rec.begin(), rec.end(), common::CmpFirst);
+      XGBOOST_PARALLEL_STABLE_SORT(rec.begin(), rec.end(), common::CmpFirst);
       // calculate AUC
       double sum_pospair = 0.0;
       double sum_npos = 0.0, sum_nneg = 0.0, buf_pos = 0.0, buf_neg = 0.0;
@@ -321,7 +321,7 @@ struct EvalPrecision : public EvalRankList{
  protected:
   bst_float EvalMetric(std::vector< std::pair<bst_float, unsigned> > &rec) const override {
     // calculate Precision
-    std::sort(rec.begin(), rec.end(), common::CmpFirst);
+    std::stable_sort(rec.begin(), rec.end(), common::CmpFirst);
     unsigned nhit = 0;
     for (size_t j = 0; j < rec.size() && j < this->topn_; ++j) {
       nhit += (rec[j].second != 0);
@@ -369,7 +369,7 @@ struct EvalMAP : public EvalRankList {
 
  protected:
   bst_float EvalMetric(std::vector< std::pair<bst_float, unsigned> > &rec) const override {
-    std::sort(rec.begin(), rec.end(), common::CmpFirst);
+    std::stable_sort(rec.begin(), rec.end(), common::CmpFirst);
     unsigned nhits = 0;
     double sumap = 0.0;
     for (size_t i = 0; i < rec.size(); ++i) {
@@ -481,7 +481,7 @@ struct EvalAucPR : public Metric {
         total_neg += wt * (1.0f - h_labels[j]);
         rec.emplace_back(h_preds[j], j);
       }
-      XGBOOST_PARALLEL_SORT(rec.begin(), rec.end(), common::CmpFirst);
+      XGBOOST_PARALLEL_STABLE_SORT(rec.begin(), rec.end(), common::CmpFirst);
       // we need pos > 0 && neg > 0
       if (0.0 == total_pos || 0.0 == total_neg) {
         auc_error += 1;