typed_array_low_level.cpp

Create a typed_array object from an array_data object.

Create a typed_array object from an array_data object.The array_data object is created with 5 float32 elements where the value at index 2 is missing. The typed_array is created from the array_data and the data is accessed.

 
// #include <sparrow/array/array_data.hpp>
 
int main()
{
    // create array_data with 5 float32 elements
    // where the value at index 2 is missing
    /*using value_type = float;
    static const float no_value = NAN;
    auto n = 5;
 
    // create the array_data object
    sparrow::array_data data;
    data.type = sparrow::data_descriptor(sparrow::arrow_traits<value_type>::type_id);
 
    // create a bitmap with all bits set to true except for
    // the missing value at index 2
    data.bitmap = sparrow::dynamic_bitset<uint8_t>(n, true);
    data.bitmap.set(2, false);
 
 
    //  the buffer holding the actual data
    const size_t buffer_size = (n * sizeof(value_type)) / sizeof(uint8_t);
    sparrow::buffer<uint8_t> buffer(buffer_size);
 
    buffer.data<value_type>()[0] = 1.0;
    buffer.data<value_type>()[1] = 2.0;
    buffer.data<value_type>()[2] = no_value;  // missing value, will lead to errors if used
    buffer.data<value_type>()[3] = 4.0;
    buffer.data<value_type>()[4] = 5.0;
 
    // add the buffer to the array_data
    data.buffers.push_back(buffer);
    data.length = static_cast<std::int64_t>(n);
    data.offset = static_cast<std::int64_t>(0);
    data.child_data.emplace_back();
 
    // create a typed_array object from the array_data
    auto array = sparrow::typed_array<value_type>(data);
 
    // access the data
    for (auto i = 0; i < n; ++i) {
        if (array.bitmap()[i]) {
            std::cout << array[i].value() << std::endl;
        } else {
            std::cout << "missing value" << std::endl;
        }
    }*/
 
    return 0;
}