in cpp/code/basic_arrow.cc [99:132]
arrow::Status VisitorSummationExample() {
StartRecipe("VisitorSummationExample");
std::shared_ptr<arrow::Schema> schema = arrow::schema({
arrow::field("a", arrow::int32()),
arrow::field("b", arrow::float64()),
});
int32_t num_rows = 3;
std::vector<std::shared_ptr<arrow::Array>> columns;
arrow::Int32Builder a_builder = arrow::Int32Builder();
std::vector<int32_t> a_vals = {1, 2, 3};
ARROW_RETURN_NOT_OK(a_builder.AppendValues(a_vals));
ARROW_ASSIGN_OR_RAISE(auto a_arr, a_builder.Finish());
columns.push_back(a_arr);
arrow::DoubleBuilder b_builder = arrow::DoubleBuilder();
std::vector<double> b_vals = {4.0, 5.0, 6.0};
ARROW_RETURN_NOT_OK(b_builder.AppendValues(b_vals));
ARROW_ASSIGN_OR_RAISE(auto b_arr, b_builder.Finish());
columns.push_back(b_arr);
auto batch = arrow::RecordBatch::Make(schema, num_rows, columns);
// Call
TableSummation summation;
ARROW_ASSIGN_OR_RAISE(auto total, summation.Compute(batch));
rout << "Total is " << total;
EndRecipe("VisitorSummationExample");
EXPECT_EQ(total, 21.0);
return arrow::Status::OK();
}