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Fix pairwise objective with NDCG metric along with custom gain. (#10100)

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* Fix pairwise objective with NDCG metric.

- Allow setting `ndcg_exp_gain` for `rank:pairwise`.

This is useful when using pairwise for objective but ndcg for metric.
This commit is contained in:
Jiaming Yuan
2024-03-11 14:54:10 +08:00
committed by GitHub
parent 06c9702028
commit 1450aebb74
3 changed files with 26 additions and 2 deletions
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9
src/objective/lambdarank_obj.cc
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@@ -474,7 +474,6 @@ class LambdaRankMAP : public LambdaRankObj<LambdaRankMAP, ltr::MAPCache> {
public:
void GetGradientImpl(std::int32_t iter, const HostDeviceVector<float>& predt,
const MetaInfo& info, linalg::Matrix<GradientPair>* out_gpair) {
CHECK(param_.ndcg_exp_gain) << "NDCG gain can not be set for the MAP objective.";
if (ctx_->IsCUDA()) {
return cuda_impl::LambdaRankGetGradientMAP(
ctx_, iter, predt, info, GetCache(), ti_plus_.View(ctx_->Device()),
@@ -564,7 +563,6 @@ class LambdaRankPairwise : public LambdaRankObj<LambdaRankPairwise, ltr::Ranking
public:
void GetGradientImpl(std::int32_t iter, const HostDeviceVector<float>& predt,
const MetaInfo& info, linalg::Matrix<GradientPair>* out_gpair) {
CHECK(param_.ndcg_exp_gain) << "NDCG gain can not be set for the pairwise objective.";
if (ctx_->IsCUDA()) {
return cuda_impl::LambdaRankGetGradientPairwise(
ctx_, iter, predt, info, GetCache(), ti_plus_.View(ctx_->Device()),
@@ -610,6 +608,13 @@ class LambdaRankPairwise : public LambdaRankObj<LambdaRankPairwise, ltr::Ranking
[[nodiscard]] const char* DefaultEvalMetric() const override {
return this->RankEvalMetric("ndcg");
}
[[nodiscard]] Json DefaultMetricConfig() const override {
Json config{Object{}};
config["name"] = String{DefaultEvalMetric()};
config["lambdarank_param"] = ToJson(param_);
return config;
}
};
#if !defined(XGBOOST_USE_CUDA)