# HGTConvο

class dgl.nn.pytorch.conv.HGTConv(in_size, head_size, num_heads, num_ntypes, num_etypes, dropout=0.2, use_norm=False)[source]ο

Bases: Module

Heterogeneous graph transformer convolution from Heterogeneous Graph Transformer

Given a graph $$G(V, E)$$ and input node features $$H^{(l-1)}$$, it computes the new node features as follows:

Compute a multi-head attention score for each edge $$(s, e, t)$$ in the graph:

$\begin{split}Attention(s, e, t) = \text{Softmax}\left(||_{i\in[1,h]}ATT-head^i(s, e, t)\right) \\ ATT-head^i(s, e, t) = \left(K^i(s)W^{ATT}_{\phi(e)}Q^i(t)^{\top}\right)\cdot \frac{\mu_{(\tau(s),\phi(e),\tau(t)}}{\sqrt{d}} \\ K^i(s) = \text{K-Linear}^i_{\tau(s)}(H^{(l-1)}[s]) \\ Q^i(t) = \text{Q-Linear}^i_{\tau(t)}(H^{(l-1)}[t]) \\\end{split}$

Compute the message to send on each edge $$(s, e, t)$$:

$\begin{split}Message(s, e, t) = ||_{i\in[1, h]} MSG-head^i(s, e, t) \\ MSG-head^i(s, e, t) = \text{M-Linear}^i_{\tau(s)}(H^{(l-1)}[s])W^{MSG}_{\phi(e)} \\\end{split}$

Send messages to target nodes $$t$$ and aggregate:

$\tilde{H}^{(l)}[t] = \sum_{\forall s\in \mathcal{N}(t)}\left( Attention(s,e,t) \cdot Message(s,e,t)\right)$

Compute new node features:

$H^{(l)}[t]=\text{A-Linear}_{\tau(t)}(\sigma(\tilde(H)^{(l)}[t])) + H^{(l-1)}[t]$
Parameters:
• in_size (int) β Input node feature size.

• head_size (int) β Output head size. The output node feature size is head_size * num_heads.

• num_heads (int) β Number of heads. The output node feature size is head_size * num_heads.

• num_ntypes (int) β Number of node types.

• num_etypes (int) β Number of edge types.

• dropout (optional, float) β Dropout rate.

• use_norm (optiona, bool) β If true, apply a layer norm on the output node feature.

Examples

forward(g, x, ntype, etype, *, presorted=False)[source]ο

Forward computation.

Parameters:
• g (DGLGraph) β The input graph.

• x (torch.Tensor) β A 2D tensor of node features. Shape: $$(|V|, D_{in})$$.

• ntype (torch.Tensor) β An 1D integer tensor of node types. Shape: $$(|V|,)$$.

• etype (torch.Tensor) β An 1D integer tensor of edge types. Shape: $$(|E|,)$$.

• presorted (bool, optional) β Whether both the nodes and the edges of the input graph have been sorted by their types. Forward on pre-sorted graph may be faster. Graphs created by to_homogeneous() automatically satisfy the condition. Also see reorder_graph() for manually reordering the nodes and edges.

Returns:

New node features. Shape: $$(|V|, D_{head} * N_{head})$$.

Return type:

torch.Tensor