torch_geometric.nn.conv.SSGConv
- class SSGConv(in_channels: int, out_channels: int, alpha: float, K: int = 1, cached: bool = False, add_self_loops: bool = True, bias: bool = True, **kwargs)[source]
Bases:
MessagePassing
The simple spectral graph convolutional operator from the “Simple Spectral Graph Convolution” paper.
\[\mathbf{X}^{\prime} = \frac{1}{K} \sum_{k=1}^K\left((1-\alpha) {\left(\mathbf{\hat{D}}^{-1/2} \mathbf{\hat{A}} \mathbf{\hat{D}}^{-1/2} \right)}^k \mathbf{X}+\alpha \mathbf{X}\right) \mathbf{\Theta},\]where \(\mathbf{\hat{A}} = \mathbf{A} + \mathbf{I}\) denotes the adjacency matrix with inserted self-loops and \(\hat{D}_{ii} = \sum_{j=0} \hat{A}_{ij}\) its diagonal degree matrix. The adjacency matrix can include other values than
1
representing edge weights via the optionaledge_weight
tensor.SSGConv
is an improved operator ofSGConv
by introducing thealpha
parameter to address the oversmoothing issue.- Parameters:
in_channels (int) – Size of each input sample, or
-1
to derive the size from the first input(s) to the forward method.out_channels (int) – Size of each output sample.
alpha (float) – Teleport probability \(\alpha \in [0, 1]\).
K (int, optional) – Number of hops \(K\). (default:
1
)cached (bool, optional) – If set to
True
, the layer will cache the computation of \(\frac{1}{K} \sum_{k=1}^K\left((1-\alpha) {\left(\mathbf{\hat{D}}^{-1/2} \mathbf{\hat{A}} \mathbf{\hat{D}}^{-1/2} \right)}^k \mathbf{X}+ \alpha \mathbf{X}\right)\) on first execution, and will use the cached version for further executions. This parameter should only be set toTrue
in transductive learning scenarios. (default:False
)add_self_loops (bool, optional) – If set to
False
, will not add self-loops to the input graph. (default:True
)bias (bool, optional) – If set to
False
, the layer will not learn an additive bias. (default:True
)**kwargs (optional) – Additional arguments of
torch_geometric.nn.conv.MessagePassing
.
- Shapes:
input: node features \((|\mathcal{V}|, F_{in})\), edge indices \((2, |\mathcal{E}|)\), edge weights \((|\mathcal{E}|)\) (optional)
output: node features \((|\mathcal{V}|, F_{out})\)