Function GrowTree

tests/cpp/tree/test_tree_model.cc:108–144

}

void GrowTree(RegTree* p_tree) {
  SimpleLCG lcg;
  size_t n_expands = 10;
  constexpr size_t kCols = 256;
  SimpleRealUniformDistribution<double> coin(0.0, 1.0);
  SimpleRealUniformDistribution<double> feat(0.0, kCols);
  SimpleRealUniformDistribution<double> split_cat(0.0, 128.0);
  SimpleRealUniformDistribution<double> split_value(0.0, kCols);

  std::stack<bst_node_t> stack;
  stack.push(RegTree::kRoot);
  auto& tree = *p_tree;

  for (size_t i = 0; i < n_expands; ++i) {
    auto is_cat = coin(&lcg) <= 0.5;
    bst_node_t node = stack.top();
    stack.pop();

    bst_feature_t f = feat(&lcg);
    if (is_cat) {
      bst_cat_t cat = common::AsCat(split_cat(&lcg));
      std::vector<uint32_t> split_cats(
          LBitField32::ComputeStorageSize(cat + 1));
      LBitField32 bitset{split_cats};
      bitset.Set(cat);
      tree.ExpandCategorical(node, f, split_cats, true, 1.0, 2.0, 3.0, 11.0, 2.0,
                             /*left_sum=*/3.0, /*right_sum=*/4.0);
    } else {
      auto split = split_value(&lcg);
      tree.ExpandNode(node, f, split, true, 1.0, 2.0, 3.0, 11.0, 2.0,
                      /*left_sum=*/3.0, /*right_sum=*/4.0);
    }

    stack.push(tree[node].LeftChild());
    stack.push(tree[node].RightChild());
  }
}

void CheckReload(RegTree const &tree) {
  Json out{Object()};