Example of using compute functions to compare arrays

common_functions_example.cc

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#include <arrow/array/builder_binary.h>
#include <arrow/array/builder_decimal.h>
#include <arrow/array/builder_primitive.h>
#include <arrow/compute/api.h>
#include <arrow/compute/exec.h>
#include <arrow/result.h>
#include <arrow/status.h>
#include <arrow/table.h>
#include <arrow/type_fwd.h>

#include <iostream>
#include <memory>
#include <stdexcept>

namespace {

// Utility functions for converting arrow::Result & arrow::Status into
// exceptions
template <typename T> T throw_or_assign(arrow::Result<T> value) {
  if (!value.ok()) {
    throw std::runtime_error(value.status().ToString());
  }
  return value.MoveValueUnsafe();
}

void throw_not_ok(const arrow::Status &status) {
  if (!status.ok()) {
    throw std::runtime_error(status.ToString());
  }
}

std::shared_ptr<arrow::Table>
CreateSampleTable(const std::vector<std::optional<int32_t>> values) {
  arrow::Int32Builder x_builder;
  for (std::optional<int32_t> value : values) {
    if (value.has_value()) {
      throw_not_ok(x_builder.Append(*value));
    } else {
      throw_not_ok(x_builder.AppendNull());
    }
  }

  std::shared_ptr<arrow::Array> x_arr = throw_or_assign(x_builder.Finish());

  std::shared_ptr<arrow::Schema> schema =
      arrow::schema({arrow::field("x", arrow::int32())});
  return arrow::Table::Make(schema, {x_arr}, x_arr->length());
}

void RunTest() {
  std::shared_ptr<arrow::Table> table_a = CreateSampleTable({1, 5, 7});
  std::shared_ptr<arrow::Table> table_b = CreateSampleTable({1, {}, 4});

  std::shared_ptr<arrow::Array> array_a = table_a->column(0)->chunk(0);
  std::shared_ptr<arrow::Array> array_b = table_b->column(0)->chunk(0);

  std::cout << "LHS" << array_a->ToString() << std::endl;
  std::cout << "RHS" << array_b->ToString() << std::endl;

  auto call_and_print = [&](std::string_view op) {
    arrow::Datum op_result = throw_or_assign(
        arrow::compute::CallFunction(std::string(op), {array_a, array_b}));
    std::cout << op << ": " << op_result.make_array()->ToString() << std::endl;
  };
  call_and_print("equal");
  call_and_print("less");
  call_and_print("less_equal");
  call_and_print("greater");
  call_and_print("greater_equal");
}

} // namespace

int main() {
  try {
    RunTest();
  } catch (std::runtime_error &err) {
    std::cerr << "An error occurred: " << err.what() << std::endl;
    return 1;
  }
  return 0;
}