[Graphbolt] Convert a data block to dgl graphs (dmlc#6228)

python/dgl/graphbolt/minibatch.py

@@ -5,6 +5,9 @@
 
 import torch
 
+import dgl
+
+from .base import etype_str_to_tuple
 from .sampled_subgraph import SampledSubgraph
 
 __all__ = ["MiniBatch"]
@@ -122,3 +125,90 @@ class MiniBatch:
     Representation of compacted nodes corresponding to 'negative_tail', where
     all node ids inside are compacted.
     """
+
+    def to_dgl_graphs(self):
+        """Transforming a data graph into DGL graphs necessitates constructing a
+        graphical structure and assigning features to the nodes and edges within
+        the graphs.
+        """
+        if not self.sampled_subgraphs:
+            return None
+
+        is_heterogeneous = isinstance(
+            self.sampled_subgraphs[0].node_pairs, Dict
+        )
+
+        if is_heterogeneous:
+            graphs = []
+            for subgraph in self.sampled_subgraphs:
+                graphs.append(
+                    dgl.heterograph(
+                        {
+                            etype_str_to_tuple(etype): v
+                            for etype, v in subgraph.node_pairs.items()
+                        }
+                    )
+                )
+        else:
+            graphs = [
+                dgl.graph(subgraph.node_pairs)
+                for subgraph in self.sampled_subgraphs
+            ]
+
+        if is_heterogeneous:
+            # Assign node features to the outermost layer's nodes.
+            if self.node_features:
+                for (
+                    node_type,
+                    feature_name,
+                ), feature in self.node_features.items():
+                    graphs[0].nodes[node_type].data[feature_name] = feature
+            # Assign edge features.
+            if self.edge_features:
+                for graph, edge_feature in zip(graphs, self.edge_features):
+                    for (
+                        edge_type,
+                        feature_name,
+                    ), feature in edge_feature.items():
+                        graph.edges[etype_str_to_tuple(edge_type)].data[
+                            feature_name
+                        ] = feature
+            # Assign reverse node ids to the outermost layer's nodes.
+            reverse_row_node_ids = self.sampled_subgraphs[
+                0
+            ].reverse_row_node_ids
+            if reverse_row_node_ids:
+                for node_type, reverse_ids in reverse_row_node_ids.items():
+                    graphs[0].nodes[node_type].data[dgl.NID] = reverse_ids
+            # Assign reverse edges ids.
+            for graph, subgraph in zip(graphs, self.sampled_subgraphs):
+                if subgraph.reverse_edge_ids:
+                    for (
+                        edge_type,
+                        reverse_ids,
+                    ) in subgraph.reverse_edge_ids.items():
+                        graph.edges[etype_str_to_tuple(edge_type)].data[
+                            dgl.EID
+                        ] = reverse_ids
+        else:
+            # Assign node features to the outermost layer's nodes.
+            if self.node_features:
+                for feature_name, feature in self.node_features.items():
+                    graphs[0].ndata[feature_name] = feature
+            # Assign edge features.
+            if self.edge_features:
+                for graph, edge_feature in zip(graphs, self.edge_features):
+                    for feature_name, feature in edge_feature.items():
+                        graph.edata[feature_name] = feature
+            # Assign reverse node ids.
+            reverse_row_node_ids = self.sampled_subgraphs[
+                0
+            ].reverse_row_node_ids
+            if reverse_row_node_ids is not None:
+                graphs[0].ndata[dgl.NID] = reverse_row_node_ids
+            # Assign reverse edges ids.
+            for graph, subgraph in zip(graphs, self.sampled_subgraphs):
+                if subgraph.reverse_edge_ids is not None:
+                    graph.edata[dgl.EID] = subgraph.reverse_edge_ids
+
+        return graphs

tests/python/pytorch/graphbolt/impl/test_to_dgl_graphs.py

@@ -0,0 +1,69 @@
+import dgl
+import dgl.graphbolt as gb
+import torch
+
+
+def test_to_dgl_graphs_hetero():
+    relation = "A:relation:B"
+    node_pairs = {relation: (torch.tensor([0, 1, 2]), torch.tensor([0, 4, 5]))}
+    reverse_column_node_ids = {"B": torch.tensor([10, 11, 12, 13, 14, 16])}
+    reverse_row_node_ids = {
+        "A": torch.tensor([5, 9, 7]),
+        "B": torch.tensor([10, 11, 12, 13, 14, 16]),
+    }
+    reverse_edge_ids = {relation: torch.tensor([19, 20, 21])}
+    node_features = {
+        ("A", "x"): torch.randint(0, 10, (3,)),
+        ("B", "y"): torch.randint(0, 10, (6,)),
+    }
+    edge_features = {(relation, "x"): torch.randint(0, 10, (3,))}
+    subgraph = gb.SampledSubgraphImpl(
+        node_pairs=node_pairs,
+        reverse_column_node_ids=reverse_column_node_ids,
+        reverse_row_node_ids=reverse_row_node_ids,
+        reverse_edge_ids=reverse_edge_ids,
+    )
+    g = gb.MiniBatch(
+        sampled_subgraphs=[subgraph],
+        node_features=node_features,
+        edge_features=[edge_features],
+    ).to_dgl_graphs()[0]
+
+    assert torch.equal(g.edges()[0], node_pairs[relation][0])
+    assert torch.equal(g.edges()[1], node_pairs[relation][1])
+    assert torch.equal(g.ndata[dgl.NID]["A"], reverse_row_node_ids["A"])
+    assert torch.equal(g.ndata[dgl.NID]["B"], reverse_row_node_ids["B"])
+    assert torch.equal(g.edata[dgl.EID], reverse_edge_ids[relation])
+    assert torch.equal(g.nodes["A"].data["x"], node_features[("A", "x")])
+    assert torch.equal(g.nodes["B"].data["y"], node_features[("B", "y")])
+    assert torch.equal(
+        g.edges[gb.etype_str_to_tuple(relation)].data["x"],
+        edge_features[(relation, "x")],
+    )
+
+
+def test_to_dgl_graphs_homo():
+    node_pairs = (torch.tensor([0, 1, 2]), torch.tensor([0, 4, 5]))
+    reverse_column_node_ids = torch.tensor([10, 11, 12])
+    reverse_row_node_ids = torch.tensor([10, 11, 12, 13, 14, 16])
+    reverse_edge_ids = torch.tensor([19, 20, 21])
+    node_features = {"x": torch.randint(0, 10, (6,))}
+    edge_features = {"x": torch.randint(0, 10, (3,))}
+    subgraph = gb.SampledSubgraphImpl(
+        node_pairs=node_pairs,
+        reverse_column_node_ids=reverse_column_node_ids,
+        reverse_row_node_ids=reverse_row_node_ids,
+        reverse_edge_ids=reverse_edge_ids,
+    )
+    g = gb.MiniBatch(
+        sampled_subgraphs=[subgraph],
+        node_features=node_features,
+        edge_features=[edge_features],
+    ).to_dgl_graphs()[0]
+
+    assert torch.equal(g.edges()[0], node_pairs[0])
+    assert torch.equal(g.edges()[1], node_pairs[1])
+    assert torch.equal(g.ndata[dgl.NID], reverse_row_node_ids)
+    assert torch.equal(g.edata[dgl.EID], reverse_edge_ids)
+    assert torch.equal(g.ndata["x"], node_features["x"])
+    assert torch.equal(g.edata["x"], edge_features["x"])