Method Init

cpp/src/arrow/compute/kernels/aggregate_pivot.cc:34–50

struct PivotImpl : public ScalarAggregator {
  Status Init(const PivotWiderOptions& options, const std::vector<TypeHolder>& in_types,
              ExecContext* ctx) {
    options_ = &options;
    key_type_ = in_types[0].GetSharedPtr();
    auto value_type = in_types[1].GetSharedPtr();
    FieldVector fields;
    fields.reserve(options_->key_names.size());
    values_.reserve(options_->key_names.size());
    for (const auto& key_name : options_->key_names) {
      fields.push_back(field(key_name, value_type));
      values_.push_back(MakeNullScalar(value_type));
    }
    out_type_ = struct_(std::move(fields));
    ARROW_ASSIGN_OR_RAISE(key_mapper_,
                          PivotWiderKeyMapper::Make(*key_type_, options_, ctx));
    return Status::OK();
  }

  Status Consume(KernelContext*, const ExecSpan& batch) override {
    DCHECK_EQ(batch.num_values(), 2);