Dataset Strucute:时间有向图;节点有特性;边缘没有特征;节点被标记。使用椭圆数据集
任务:对节点进行分类/预测节点标签。
数据结构:2个
.csv
节点和边文件。
#Rows = #Nodes
和 #Columns = #Features
#Rows = #Edges
我想在数据上训练各种图神经网络并从网络中提取节点嵌入。我知道这是可能的,因为 Elliptic 数据集的作者从 GCN 中提取了节点嵌入。
下面是我正在使用的 GAT 的代码。
class GAT(torch.nn.Module):
"""Graph Attention Network"""
def __init__(self, dim_in, dim_h, dim_out, heads=24):
super().__init__()
self.gat1 = GATv2Conv(dim_in, dim_h, heads=heads)
self.gat2 = GATv2Conv(dim_h*heads, dim_out, heads=1)
self.optimizer = torch.optim.Adam(self.parameters(),
lr=0.25,
weight_decay=5e-4)
def forward(self, x, edge_index):
h = F.dropout(x, p=0.5, training=self.training)
h = self.gat1(x, edge_index)
h = F.elu(h)
h = F.dropout(h, p=0.5, training=self.training)
h = self.gat2(h, edge_index)
return h, F.log_softmax(h, dim=1)
此函数返回经过训练的模型
def train(model, data , epochs = 200):
"""Train a GNN model and return the trained model."""
criterion = torch.nn.CrossEntropyLoss()
optimizer = model.optimizer
model = model.to(device)
model.train()
for epoch in range(epochs+1):
# Training
optimizer.zero_grad()
_, out = model(data.x.to(device), data.edge_index.to(device))
loss = criterion(out[data.train_mask].to(device), data.y[data.train_mask].to(device))
loss.backward()
optimizer.step()
# Print metrics every 10 epochs
if(epoch % 10 == 0):
print(f'Epoch {epoch:>3} | Train Loss: {loss:.3f}')
return model
我需要对代码进行哪些修改才能提取节点嵌入?
您好,您可以编写一个方法,类似于使用子图加载器来处理大图:
def representation(self,x_all): for i, conv in enumerate(self.convs): xs = [] for batch in subgraph_loader: x = x_all[batch.n_id.to(x_all.device)].to(device) x = conv(x, batch.edge_index.to(device)) if i < len(self.convs) - 1: x = F.elu_(x) xs.append(x[:batch.batch_size].cpu()) pbar.update(batch.batch_size) x_all = torch.cat(xs, dim=0) pbar.close() return x_all
来自 https://github.com/pyg-team/pytorch_geometric/blob/master/examples/cluster_gcn_reddit.py
如果图形不是很大,您还可以使用 pytorch 几何实用程序中的 get_embeddings :
https://pytorch-geometric.readthedocs.io/en/latest/_modules/torch_geometric/utils/embedding.html