variable_shape.cpp

#include <adios2.h>

void write(adios2::ADIOS &adios)
{
    adios2::IO outIO = adios.DeclareIO("Output");
    adios2::Engine writer = outIO.Open("test.bp", adios2::Mode::Write);

    auto var = outIO.DefineVariable<double>("v", {1, 3}, {0, 0}, {1, 3});

    std::vector<double> buf(10 * 3, 0.0);

    for (int i = 0; i < buf.size(); i++) {
        buf[i] = i;
    }

    std::cout << "Writing:" << std::endl;
    for (size_t i = 1; i <= 10; i++) {
        writer.BeginStep();

        var.SetShape({i, 3});
        var.SetSelection({{0, 0}, {i, 3}});

        std::cout << "Step " << i << " shape (" << var.Shape()[0] << ", "
                  << var.Shape()[1] << ")" << std::endl;

        writer.Put(var, buf.data());

        writer.EndStep();
    }

    writer.Close();
}

void read(adios2::ADIOS &adios)
{
    adios2::IO inIO = adios.DeclareIO("Input");
    adios2::Engine reader = inIO.Open("test.bp", adios2::Mode::Read);

    std::cout << "Reading:" << std::endl;

    int i = 0;
    while (true) {
        adios2::StepStatus status =
            reader.BeginStep(adios2::StepMode::NextAvailable);

        if (status != adios2::StepStatus::OK) {
            break;
        }

        auto var = inIO.InquireVariable<double>("v");

        std::cout << "Step " << i << " shape (" << var.Shape()[0] << ", "
                  << var.Shape()[1] << ")" << std::endl;

        i++;
    }

    reader.Close();
}

int main(int argc, char *argv[])
{
    MPI_Init(&argc, &argv);

    adios2::ADIOS adios(MPI_COMM_WORLD);

    write(adios);
    read(adios);

    MPI_Finalize();
}