dgl.readout_edges¶
-
dgl.
readout_edges
(graph, feat, weight=None, *, op='sum', etype=None)[source]¶ Sum the edge feature
feat
ingraph
, optionally multiplies it by a edgeweight
.The function is commonly used as a readout function on a batch of graphs to generate graph-level representation. Thus, the result tensor shape depends on the batch size of the input graph. Given a graph of batch size \(B\), and a feature size of \(D\), the result shape will be \((B, D)\), with each row being the aggregated edge features of each graph.
- Parameters
graph (DGLGraph.) – The input graph.
feat (str) – The edge feature name.
weight (str, optional) – The edge weight feature name. If None, no weighting will be performed, otherwise, weight each edge feature with field
feat
. for summation. The weight feature shape must be compatible with an element-wise multiplication with the feature tensor.op (str, optional) – Readout operator. Can be ‘sum’, ‘max’, ‘min’, ‘mean’.
etype (str or (str, str, str), optional) –
The type names of the edges. The allowed type name formats are:
(str, str, str)
for source node type, edge type and destination node type.or one
str
edge type name if the name can uniquely identify a triplet format in the graph.
Can be omitted if the graph has only one type of edges.
- Returns
Result tensor.
- Return type
Tensor
Examples
>>> import dgl >>> import torch as th
Create two
DGLGraph
objects and initialize their edge features.>>> g1 = dgl.graph(([0, 1], [1, 0])) # Graph 1 >>> g1.edata['h'] = th.tensor([1., 2.]) >>> g2 = dgl.graph(([0, 1], [1, 2])) # Graph 2 >>> g2.edata['h'] = th.tensor([2., 3.])
Sum over one graph:
>>> dgl.readout_edges(g1, 'h') tensor([3.]) # 1 + 2
Sum over a batched graph:
>>> bg = dgl.batch([g1, g2]) >>> dgl.readout_edges(bg, 'h') tensor([3., 5.]) # [1 + 2, 2 + 3]
Weighted sum:
>>> bg.edata['w'] = th.tensor([.1, .2, .1, .5]) >>> dgl.readout_edges(bg, 'h', 'w') tensor([.5, 1.7])
Readout by max:
>>> dgl.readout_edges(bg, 'w', op='max') tensor([2., 3.])
See also