[FEA] DGL Examples (#4583)

Adds updated examples for the new cuGraph-DGL API. 

Also fixes a minor performance issue by allowing access to tensors through an `EmbeddingView`.

Authors:
  - Alex Barghi (https://github.com/alexbarghi-nv)
  - Ralph Liu (https://github.com/nv-rliu)

Approvers:
  - Mike Sarahan (https://github.com/msarahan)
  - Tingyu Wang (https://github.com/tingyu66)
  - Rick Ratzel (https://github.com/rlratzel)

URL: #4583

conda/environments/all_cuda-118_arch-x86_64.yaml

@@ -42,6 +42,7 @@ dependencies:
 - numpy>=1.23,<2.0a0
 - numpydoc
 - nvcc_linux-64=11.8
+- ogb
 - openmpi
 - packaging>=21
 - pandas
@@ -74,6 +75,7 @@ dependencies:
 - sphinxcontrib-websupport
 - thriftpy2!=0.5.0,!=0.5.1
 - torchdata
+- torchmetrics
 - ucx-proc=*=gpu
 - ucx-py==0.40.*,>=0.0.0a0
 - wget

conda/environments/all_cuda-125_arch-x86_64.yaml

@@ -47,6 +47,7 @@ dependencies:
 - numba>=0.57
 - numpy>=1.23,<2.0a0
 - numpydoc
+- ogb
 - openmpi
 - packaging>=21
 - pandas
@@ -79,6 +80,7 @@ dependencies:
 - sphinxcontrib-websupport
 - thriftpy2!=0.5.0,!=0.5.1
 - torchdata
+- torchmetrics
 - ucx-proc=*=gpu
 - ucx-py==0.40.*,>=0.0.0a0
 - wget

dependencies.yaml

@@ -713,6 +713,8 @@ dependencies:
           - &pytorch_unsuffixed pytorch>=2.0,<2.2.0a0
           - torchdata
           - pydantic
+          - ogb
+          - torchmetrics
 
     specific:
       - output_types: [requirements]

python/cugraph-dgl/cugraph_dgl/dataloading/dataloader.py

@@ -140,6 +140,10 @@ def __init__(
         self.__graph = graph
         self.__device = device
 
+    @property
+    def _batch_size(self):
+        return self.__batch_size
+
     @property
     def dataset(
         self,

python/cugraph-dgl/cugraph_dgl/dataloading/neighbor_sampler.py

@@ -194,7 +194,7 @@ def sample(
 
         if g.is_homogeneous:
             indices = torch.concat(list(indices))
-            ds.sample_from_nodes(indices, batch_size=batch_size)
+            ds.sample_from_nodes(indices.long(), batch_size=batch_size)
             return HomogeneousSampleReader(
                 ds.get_reader(), self.output_format, self.edge_dir
             )

python/cugraph-dgl/cugraph_dgl/graph.py

@@ -29,6 +29,7 @@
     HeteroNodeDataView,
     HeteroEdgeView,
     HeteroEdgeDataView,
+    EmbeddingView,
 )
 
 
@@ -567,8 +568,8 @@ def _has_n_emb(self, ntype: str, emb_name: str) -> bool:
         return (ntype, emb_name) in self.__ndata_storage
 
     def _get_n_emb(
-        self, ntype: str, emb_name: str, u: Union[str, TensorType]
-    ) -> "torch.Tensor":
+        self, ntype: Union[str, None], emb_name: str, u: Union[str, TensorType]
+    ) -> Union["torch.Tensor", "EmbeddingView"]:
         """
         Gets the embedding of a single node type.
         Unlike DGL, this function takes the string node
@@ -583,11 +584,11 @@ def _get_n_emb(
         u: Union[str, TensorType]
             Nodes to get the representation of, or ALL
             to get the representation of all nodes of
-            the given type.
+            the given type (returns embedding view).
 
         Returns
         -------
-        torch.Tensor
+        Union[torch.Tensor, cugraph_dgl.view.EmbeddingView]
             The embedding of the given edge type with the given embedding name.
         """
 
@@ -598,9 +599,14 @@ def _get_n_emb(
                 raise ValueError("Must provide the node type for a heterogeneous graph")
 
         if dgl.base.is_all(u):
-            u = torch.arange(self.num_nodes(ntype), dtype=self.idtype, device="cpu")
+            return EmbeddingView(
+                self.__ndata_storage[ntype, emb_name], self.num_nodes(ntype)
+            )
 
         try:
+            print(
+                u,
+            )
             return self.__ndata_storage[ntype, emb_name].fetch(
                 _cast_to_torch_tensor(u), "cuda"
             )
@@ -644,7 +650,9 @@ def _get_e_emb(
         etype = self.to_canonical_etype(etype)
 
         if dgl.base.is_all(u):
-            u = torch.arange(self.num_edges(etype), dtype=self.idtype, device="cpu")
+            return EmbeddingView(
+                self.__edata_storage[etype, emb_name], self.num_edges(etype)
+            )
 
         try:
             return self.__edata_storage[etype, emb_name].fetch(

python/cugraph-dgl/cugraph_dgl/view.py

@@ -12,6 +12,8 @@
 # limitations under the License.
 
 
+import warnings
+
 from collections import defaultdict
 from collections.abc import MutableMapping
 from typing import Union, Dict, List, Tuple
@@ -20,11 +22,45 @@
 
 import cugraph_dgl
 from cugraph_dgl.typing import TensorType
+from cugraph_dgl.utils.cugraph_conversion_utils import _cast_to_torch_tensor
 
 torch = import_optional("torch")
 dgl = import_optional("dgl")
 
 
+class EmbeddingView:
+    def __init__(self, storage: "dgl.storages.base.FeatureStorage", ld: int):
+        self.__ld = ld
+        self.__storage = storage
+
+    def __getitem__(self, u: TensorType) -> "torch.Tensor":
+        u = _cast_to_torch_tensor(u)
+        try:
+            return self.__storage.fetch(
+                u,
+                "cuda",
+            )
+        except RuntimeError as ex:
+            warnings.warn(
+                "Got error accessing data, trying again with index on device: "
+                + str(ex)
+            )
+            return self.__storage.fetch(
+                u.cuda(),
+                "cuda",
+            )
+
+    @property
+    def shape(self) -> "torch.Size":
+        try:
+            f = self.__storage.fetch(torch.tensor([0]), "cpu")
+        except RuntimeError:
+            f = self.__storage.fetch(torch.tensor([0], device="cuda"), "cuda")
+        sz = [s for s in f.shape]
+        sz[0] = self.__ld
+        return torch.Size(tuple(sz))
+
+
 class HeteroEdgeDataView(MutableMapping):
     """
     Duck-typed version of DGL's HeteroEdgeDataView.