first aten try

aten/cpu/cluster.cpp

+#include <torch/torch.h>
+
+
+at::Tensor graclus(at::Tensor row, at::Tensor col, at::Tensor weight) {
+  return row;
+}
+
+
+at::Tensor grid(at::Tensor pos, at::Tensor size, at::Tensor start, at::Tensor end) {
+  if (!start.defined()) start = std::get<0>(pos.min(1));
+  if (!end.defined()) end = std::get<0>(pos.max(1));
+
+  size = size.toType(pos.type());
+  start = start.toType(pos.type());
+  end = end.toType(pos.type());
+
+  pos = pos - start.view({ 1, -1 });
+  auto num_voxels = ((end - start) / size).toType(at::kLong);
+  num_voxels = (num_voxels + 1).cumsum(0);
+  num_voxels = num_voxels - num_voxels[0];
+  num_voxels[0] = 1;
+
+  auto cluster = pos / size.view({ 1, -1 });
+  cluster = cluster.toType(at::kLong);
+  cluster *= num_voxels.view({ 1, -1 });
+  cluster = cluster.sum(1);
+
+  return cluster;
+}
+
+
+PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
+  m.def("graclus", &graclus, "Graclus (CPU)", py::arg("row"), py::arg("col"), py::arg("weight"));
+  m.def("grid", &grid, "Grid (CPU)", py::arg("pos"), py::arg("size"), py::arg("start"),
+        py::arg("end"));
+}

aten/cpu/cluster.py

+import torch
+
+import cluster_cpu
+
+
+def grid_cluster(pos, size, start, end):
+    return cluster_cpu.grid(pos, size, start, end)
+
+
+pos = torch.tensor([[1, 1], [3, 3], [5, 5], [7, 7]], dtype=torch.uint8)
+size = torch.tensor([2, 2])
+start = torch.tensor([0, 0])
+end = torch.tensor([7, 7])
+print('pos', pos.tolist())
+print('size', size.tolist())
+cluster = grid_cluster(pos, size, start, end)
+print('result', cluster.tolist(), cluster.dtype)

aten/cpu/setup.py

+from setuptools import setup
+from torch.utils.cpp_extension import BuildExtension, CppExtension
+
+setup(
+    name='cluster',
+    ext_modules=[CppExtension('cluster_cpu', ['cluster.cpp'])],
+    cmdclass={'build_ext': BuildExtension},
+)