Column accessor
The
column_accessor
class provides a read-only access to the column values
of the dm table as contiguoushomogeneous array.Usage example
#include <CL/sycl.hpp>
#include <iostream>
#include "oneapi/dal/table/homogen.hpp"
#include "oneapi/dal/table/column_accessor.hpp"
using namespace oneapi;
int main() {
sycl::queue queue { sycl::default_selector() };
constexpr float host_data[] = {
1.0f, 1.5f, 2.0f,
2.1f, 3.2f, 3.7f,
4.0f, 4.9f, 5.0f,
5.2f, 6.1f, 6.2f
};
constexpr std::int64_t row_count = 4;
constexpr std::int64_t column_count = 3;
auto shared_data = sycl::malloc_shared<float>(row_count * column_count, queue);
auto event = queue.memcpy(shared_data, host_data, sizeof(float) * row_count * column_count);
auto t = dal::homogen_table::wrap(queue, data, row_count, column_count, { event });
// Accessing whole elements in a first column
dal::column_accessor<const float> acc { t };
auto block = acc.pull(queue, 0);
for(std::int64_t i = 0; i < block.get_count(); i++) {
std::cout << block[i] << ", ";
}
std::cout << std::endl;
sycl::free(shared_data, queue);
return 0;
}Programming interface
All types and functions in this section are declared in the
oneapi::dal
namespace and be available via inclusion of the
oneapi/dal/table/column_accessor.hpp
header file.- template<typenameT>classcolumn_accessor
- Template Parameters
- T– The type of data values in blocks returned by the accessor. Should be const-qualified for read-only access. An accessor supports at leastfloat,double, andstd::int32_ttypes of
.
Constructors- template <typename K, typename None = std::enable_if_t<is_readonly && (std::is_base_of_v<table, K> || std::is_base_of_v<detail::table_builder, K>> column_accessor(const K &obj)
- Creates a new read-only accessor object from the table. The check that the accessor supports the table kind of
is performed. The reference to the
table is stored within the accessor to obtain data from the table.
- column_accessor(constdetail::table_builder &b)
Public Methods