Method LoadModel

src/learner.cc:898–948

  explicit LearnerIO(std::vector<std::shared_ptr<DMatrix>> cache) : LearnerConfiguration{cache} {}

  void LoadModel(Json const& in) override {
    CHECK(IsA<Object>(in));
    auto version = Version::Load(in);
    if (std::get<0>(version) == 1 && std::get<1>(version) < 6) {
      LOG(WARNING)
          << "Found JSON model saved before XGBoost 1.6, please save the model using current "
             "version again. The support for old JSON model will be discontinued in XGBoost 3.2";
    }

    auto const& learner = get<Object>(in["learner"]);
    mparam_.FromJson(learner.at("learner_model_param"));

    auto const& objective_fn = learner.at("objective");

    std::string name = get<String>(objective_fn["name"]);
    tparam_.UpdateAllowUnknown(Args{{"objective", name}});
    obj_.reset(ObjFunction::Create(name, &ctx_));
    obj_->LoadConfig(objective_fn);

    auto const& gradient_booster = learner.at("gradient_booster");
    name = get<String>(gradient_booster["name"]);
    tparam_.UpdateAllowUnknown(Args{{"booster", name}});
    tparam_.booster = CanonicalizeBoosterName(tparam_.booster);
    gbm_.reset(GradientBooster::Create(tparam_.booster, &ctx_, &learner_model_param_));
    gbm_->LoadModel(gradient_booster);

    auto const& j_attributes = get<Object const>(learner.at("attributes"));
    attributes_.clear();
    for (auto const& kv : j_attributes) {
      attributes_[kv.first] = get<String const>(kv.second);
    }

    // feature names and types are saved in xgboost 1.4
    auto it = learner.find("feature_names");
    if (it != learner.cend()) {
      auto const& feature_names = get<Array const>(it->second);
      feature_names_.resize(feature_names.size());
      std::transform(feature_names.cbegin(), feature_names.cend(), feature_names_.begin(),
                     [](Json const& fn) { return get<String const>(fn); });
    }
    it = learner.find("feature_types");
    if (it != learner.cend()) {
      auto const& feature_types = get<Array const>(it->second);
      feature_types_.resize(feature_types.size());
      std::transform(feature_types.cbegin(), feature_types.cend(), feature_types_.begin(),
                     [](Json const& fn) { return get<String const>(fn); });
    }

    this->need_configuration_ = true;
    this->ClearCaches();
  }

  void SaveModel(Json* p_out) const override {
    CHECK(!this->need_configuration_) << "Call Configure before saving model.";