Using mesh partitioner with dolfinx(ParMETIS)

mesh
1

Hi,

I am new to dolfinx. How to use mesh partitioner other than “SCOTCH” in dolfinx.

i was able to use it using the below command using dolfin. But dolfinx is not taking this command.

import dolfin as dolf
parameters[“mesh_partitioner”] = “ParMETIS”

I am using both C++ and python for coding in fenicx. So an example in C++ or Python would be helpful

Best Regards,
Leo

Thanks in Advance,

2

See: dolfinx/test_mesh_partitioners.py at main · FEniCS/dolfinx · GitHub
or similarly: performance-test/mesh.cpp at main · FEniCS/performance-test · GitHub
For reading in from file, here is a C++ example:

    std::shared_ptr<mesh::Mesh> mesh;
    {
      if (dolfinx::MPI::rank(MPI_COMM_WORLD) == 0)
        std::cout << "Reading Mesh data ..." << std::endl;

      dolfinx::io::XDMFFile file(MPI_COMM_WORLD, mesh_file, "r");
      fem::CoordinateElement cmap
          = fem::CoordinateElement(mesh::CellType::tetrahedron, 1);

      xt::xtensor<double, 2> x;
      xt::xtensor<std::int64_t, 2> topology;
   
      x = file.read_geometry_data("Grid");
      topology = file.read_topology_data("Grid");

      auto [data, offset] = graph::create_adjacency_data(topology);
      graph::AdjacencyList<std::int64_t> cells(std::move(data),                           std::move(offset));

      if (dolfinx::MPI::rank(file.comm()) == 0)
        std::cout << "Creating Mesh ..." << std::endl;

        // Set graph partitioner (prefer ParMETIS)
#ifdef HAS_PARMETIS
      auto graph_part = dolfinx::graph::parmetis::partitioner(1.01);
#elif HAS_PTSCOTCH
      auto graph_part = dolfinx::graph::scotch::partitioner(
          dolfinx::graph::scotch::strategy::scalability);
#elif HAS_KAHIP
      auto graph_part = dolfinx::graph::kahip::partitioner();
#else
#error "No mesh partitioner has been selected"
#endif

      // Create distributed mesh
      auto cell_part = dolfinx::mesh::create_cell_partitioner(graph_part);
      mesh = std::make_shared<mesh::Mesh>(mesh::create_mesh(
          MPI_COMM_WORLD, cells, cmap, x, mesh::GhostMode::none, cell_part));
    }
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