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hgt_model.py
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hgt_model.py
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import dgl
import math
import torch
import torch.nn as nn
import torch.nn.functional as F
import dgl.function as fn
from dgl.nn.functional import edge_softmax
class HGTLayer(nn.Module):
def __init__(self,
in_dim,
out_dim,
node_dict,
edge_dict,
n_heads,
dropout = 0.2,
use_norm = False):
super(HGTLayer, self).__init__()
self.in_dim = in_dim
self.out_dim = out_dim
self.node_dict = node_dict
self.edge_dict = edge_dict
self.num_types = len(node_dict)
self.num_relations = len(edge_dict)
self.total_rel = self.num_types * self.num_relations * self.num_types
self.n_heads = n_heads
self.d_k = out_dim // n_heads
self.sqrt_dk = math.sqrt(self.d_k)
self.att = None
self.k_linears = nn.ModuleList()
self.q_linears = nn.ModuleList()
self.v_linears = nn.ModuleList()
self.a_linears = nn.ModuleList()
self.norms = nn.ModuleList()
self.use_norm = use_norm
for t in range(self.num_types):
self.k_linears.append(nn.Linear(in_dim, out_dim))
self.q_linears.append(nn.Linear(in_dim, out_dim))
self.v_linears.append(nn.Linear(in_dim, out_dim))
self.a_linears.append(nn.Linear(out_dim, out_dim))
if use_norm:
self.norms.append(nn.LayerNorm(out_dim))
self.relation_pri = nn.Parameter(torch.ones(self.num_relations, self.n_heads))
self.relation_att = nn.Parameter(torch.Tensor(self.num_relations, n_heads, self.d_k, self.d_k))
self.relation_msg = nn.Parameter(torch.Tensor(self.num_relations, n_heads, self.d_k, self.d_k))
self.skip = nn.Parameter(torch.ones(self.num_types))
self.drop = nn.Dropout(dropout)
nn.init.xavier_uniform_(self.relation_att)
nn.init.xavier_uniform_(self.relation_msg)
def forward(self, G, h):
with G.local_scope():
node_dict, edge_dict = self.node_dict, self.edge_dict
for srctype, etype, dsttype in G.canonical_etypes:
sub_graph = G[srctype, etype, dsttype]
k_linear = self.k_linears[node_dict[srctype]]
v_linear = self.v_linears[node_dict[srctype]]
q_linear = self.q_linears[node_dict[dsttype]]
k = k_linear(h[srctype]).view(-1, self.n_heads, self.d_k)
v = v_linear(h[srctype]).view(-1, self.n_heads, self.d_k)
q = q_linear(h[dsttype]).view(-1, self.n_heads, self.d_k)
e_id = self.edge_dict[etype]
relation_att = self.relation_att[e_id]
relation_pri = self.relation_pri[e_id]
relation_msg = self.relation_msg[e_id]
k = torch.einsum("bij,ijk->bik", k, relation_att)
v = torch.einsum("bij,ijk->bik", v, relation_msg)
sub_graph.srcdata['k'] = k
sub_graph.dstdata['q'] = q
sub_graph.srcdata['v_%d' % e_id] = v
sub_graph.apply_edges(fn.v_dot_u('q', 'k', 't'))
attn_score = sub_graph.edata.pop('t').sum(-1) * relation_pri / self.sqrt_dk
attn_score = edge_softmax(sub_graph, attn_score, norm_by='dst')
sub_graph.edata['t'] = attn_score.unsqueeze(-1)
G.multi_update_all({etype : (fn.u_mul_e('v_%d' % e_id, 't', 'm'), fn.sum('m', 't')) \
for etype, e_id in edge_dict.items()}, cross_reducer = 'mean')
new_h = {}
for ntype in G.ntypes:
'''
Step 3: Target-specific Aggregation
x = norm( W[node_type] * gelu( Agg(x) ) + x )
'''
n_id = node_dict[ntype]
alpha = torch.sigmoid(self.skip[n_id])
t = G.nodes[ntype].data['t'].view(-1, self.out_dim)
trans_out = self.drop(self.a_linears[n_id](t))
trans_out = trans_out * alpha + h[ntype] * (1-alpha)
if self.use_norm:
new_h[ntype] = self.norms[n_id](trans_out)
else:
new_h[ntype] = trans_out
return new_h
class HGT(nn.Module):
def __init__(self, G, node_dict, edge_dict, n_inp, n_hid, n_out, n_layers, n_heads, use_norm = True):
super(HGT, self).__init__()
self.node_dict = node_dict
self.edge_dict = edge_dict
self.gcs = nn.ModuleList()
self.n_inp = n_inp
self.n_hid = n_hid
self.n_out = n_out
self.n_layers = n_layers
self.adapt_ws = nn.ModuleList()
for t in range(len(node_dict)):
self.adapt_ws.append(nn.Linear(n_inp, n_hid))
for _ in range(n_layers):
self.gcs.append(HGTLayer(n_hid, n_hid, node_dict, edge_dict, n_heads, use_norm = use_norm))
self.out = nn.Linear(n_hid, n_out)
def forward(self, G, out_key):
h = {}
for ntype in G.ntypes:
n_id = self.node_dict[ntype]
h[ntype] = F.gelu(self.adapt_ws[n_id](G.nodes[ntype].data['inp']))
for i in range(self.n_layers):
h = self.gcs[i](G, h)
return self.out(h[out_key]), h
class HeteroRGCNLayer(nn.Module):
def __init__(self, in_size, out_size, etypes):
super(HeteroRGCNLayer, self).__init__()
# W_r for each relation
self.weight = nn.ModuleDict({
name : nn.Linear(in_size, out_size) for name in etypes
})
def forward(self, G, feat_dict):
# The input is a dictionary of node features for each type
funcs = {}
for srctype, etype, dsttype in G.canonical_etypes:
# Compute W_r * h
Wh = self.weight[etype](feat_dict[srctype])
# Save it in graph for message passing
G.nodes[srctype].data['Wh_%s' % etype] = Wh
# Specify per-relation message passing functions: (message_func, reduce_func).
# Note that the results are saved to the same destination feature 'h', which
# hints the type wise reducer for aggregation.
funcs[etype] = (fn.copy_u('Wh_%s' % etype, 'm'), fn.mean('m', 'h'))
# Trigger message passing of multiple types.
# The first argument is the message passing functions for each relation.
# The second one is the type wise reducer, could be "sum", "max",
# "min", "mean", "stack"
G.multi_update_all(funcs, 'sum')
# return the updated node feature dictionary
return {ntype : G.nodes[ntype].data['h'] for ntype in G.ntypes}
class HeteroRGCN(nn.Module):
def __init__(self, G, in_size, hidden_size, out_size):
super(HeteroRGCN, self).__init__()
# create layers
self.layer1 = HeteroRGCNLayer(in_size, hidden_size, G.etypes)
self.layer2 = HeteroRGCNLayer(hidden_size, out_size, G.etypes)
def forward(self, G, out_key):
input_dict = {ntype : G.nodes[ntype].data['inp'] for ntype in G.ntypes}
h_dict = self.layer1(G, input_dict)
h_dict = {k : F.leaky_relu(h) for k, h in h_dict.items()}
h_dict = self.layer2(G, h_dict)
# get paper logits
return h_dict[out_key]