[GraphBolt] Modify docstring of `SampledSubgraph`. (#6821)

Co-authored-by: Ubuntu <ubuntu@ip-172-31-0-133.us-west-2.compute.internal>

python/dgl/graphbolt/sampled_subgraph.py

@@ -22,13 +22,11 @@ class SampledSubgraph:
     @property
     def node_pairs(
         self,
-    ) -> Union[
-        Tuple[torch.Tensor, torch.Tensor],
-        Dict[str, Tuple[torch.Tensor, torch.Tensor]],
-    ]:
-        """Returns the node pairs representing source-destination edges.
-        - If `node_pairs` is a tuple: It should be in the format ('u', 'v')
-            representing source and destination pairs.
+    ) -> Union[CSCFormatBase, Dict[str, CSCFormatBase],]:
+        """Returns the node pairs representing edges in csc format.
+        - If `node_pairs` is a CSCFormatBase: It should be in the csc format.
+            `indptr` stores the index in the data array where each column
+            starts. `indices` stores the row indices of the non-zero elements.
         - If `node_pairs` is a dictionary: The keys should be edge type and
             the values should be corresponding node pairs. The ids inside
             is heterogeneous ids."""
@@ -119,27 +117,33 @@ class SampledSubgraph:
 
         Examples
         --------
-        >>> node_pairs = {"A:relation:B": (torch.tensor([0, 1, 2]),
-        ...     torch.tensor([0, 1, 2]))}
-        >>> original_column_node_ids = {'B': torch.tensor([10, 11, 12])}
-        >>> original_row_node_ids = {'A': torch.tensor([13, 14, 15])}
+        >>> import dgl.graphbolt as gb
+        >>> import torch
+        >>> node_pairs = {"A:relation:B": gb.CSCFormatBase(
+        ...     indptr=torch.tensor([0, 1, 2, 3]),
+        ...     indices=torch.tensor([0, 1, 2]))}
+        >>> original_column_node_ids = {"B": torch.tensor([10, 11, 12])}
+        >>> original_row_node_ids = {"A": torch.tensor([13, 14, 15])}
         >>> original_edge_ids = {"A:relation:B": torch.tensor([19, 20, 21])}
-        >>> subgraph = gb.FusedSampledSubgraphImpl(
+        >>> subgraph = gb.SampledSubgraphImpl(
         ...     node_pairs=node_pairs,
         ...     original_column_node_ids=original_column_node_ids,
         ...     original_row_node_ids=original_row_node_ids,
         ...     original_edge_ids=original_edge_ids
         ... )
-        >>> edges_to_exclude = (torch.tensor([14, 15]), torch.tensor([11, 12]))
+        >>> edges_to_exclude = {"A:relation:B": (torch.tensor([14, 15]),
+        ...     torch.tensor([11, 12]))}
         >>> result = subgraph.exclude_edges(edges_to_exclude)
         >>> print(result.node_pairs)
-        {"A:relation:B": (tensor([0]), tensor([0]))}
+        {'A:relation:B': CSCFormatBase(indptr=tensor([0, 1, 1, 1]),
+                    indices=tensor([0]),
+        )}
         >>> print(result.original_column_node_ids)
         {'B': tensor([10, 11, 12])}
         >>> print(result.original_row_node_ids)
         {'A': tensor([13, 14, 15])}
         >>> print(result.original_edge_ids)
-        {"A:relation:B": tensor([19])}
+        {'A:relation:B': tensor([19])}
         """
         # TODO: Add support for value > in32, then remove this line.
         assert (