文章说明:
1)参考资料:PYG的文档。文档超链。
2)博主水平不高,如有错误,还望批评指正。
3)我在百度网盘上传这篇文章的jupyter notebook以及有关文献。提取码8488。
代码实操1:GCN的复杂实现
导入绘图的库,定义绘图函数。
from sklearn.manifold import TSNE
import matplotlib.pyplot as plt
def visualize(h,color):
z=TSNE(n_components=2).fit_transform(h.detach().cpu().numpy())
plt.figure(figsize=(10,10))
plt.xticks([])
plt.yticks([])
plt.scatter(z[:,0],z[:,1],s=70,c=color,cmap="Set2")
plt.show()
目前,我并不知道TSNE降维理论。所以,暂时把它当作一种降维技术应该够了。
导入依赖,导入数据,导入依赖。
from torch_geometric.transforms import NormalizeFeatures
from torch_geometric.datasets import Planetoid
dataset=Planetoid(root='C:/Users/19216/Desktop/project/Project1/Node_Classification2/Planetoid',name='Cora',transform=NormalizeFeatures())
data=dataset[0]
#确定具体的图
Cora数据集简单说明:特征矩阵的 s h a p e shape shape为 N × M N \times M N×M, N N N表示为论文数量, M M M表示为特征维度,对于每维,如果单词在论文中,就是1反之就是0。邻接矩阵的 s h a p e shape shape为 N × N N \times N N×N, N N N表示为论文数量,论文之间存在引用,那么就会有一条边。
import torch.nn.functional as F
from torch.nn import Linear
import torch
搭建一个多层的感知机,训练模型并且得到结果。
class MLP(torch.nn.Module):
def __init__(self,hidden_channels):
super().__init__()
self.lin1=Linear(dataset.num_features,hidden_channels)
self.lin2=Linear(hidden_channels,dataset.num_classes)
def forward(self,x):
x=self.lin1(x)
x=x.relu()
x=F.dropout(x,p=0.5,training=self.training)
x=self.lin2(x)
x=x.relu()
x=F.dropout(x,p=0.5,training=self.training)
return x
model=MLP(hidden_channels=16)
print(model)
#输出:
#MLP(
# (lin1): Linear(in_features=1433, out_features=16, bias=True)
# (lin2): Linear(in_features=16, out_features=7, bias=True)
#)
model=MLP(hidden_channels=16)
criterion=torch.nn.CrossEntropyLoss()
optimizer=torch.optim.Adam(model.parameters(),lr=0.01,weight_decay=5e-4)
def train():
model.train()
optimizer.zero_grad()
out=model(data.x)
loss=criterion(out[data.train_mask],data.y[data.train_mask])
loss.backward()
optimizer.step()
return loss
def test():
model.eval()
out=model(data.x)
pred=out.argmax(dim=1)
test_correct=pred[data.test_mask]==data.y[data.test_mask]
test_acc=int(test_correct.sum())/int(data.test_mask.sum())
return test_acc
for epoch in range(1,201):
loss=train()
print(f'Epoch: {epoch:03d}, Loss: {loss:.4f}')
#这里就不展示输出
test_acc=test()
print(f'Test Accuracy: {test_acc:.4f}')
#Test Accuracy: 0.5130
导入依赖,搭建模型
from torch_geometric.nn import GCNConv
class GCN(torch.nn.Module):
def __init__(self,hidden_channels):
super().__init__()
self.conv1=GCNConv(dataset.num_features,hidden_channels)
self.conv2=GCNConv(hidden_channels,dataset.num_classes)
def forward(self,x,edge_index):
x=self.conv1(x,edge_index)
x=x.relu()
x=F.dropout(x,p=0.5,training=self.training)
x=self.conv2(x,edge_index)
return x
model=GCN(hidden_channels=16)
print(model)
#输出:
#GCN(
# (conv1): GCNConv(1433, 16)
# (conv2): GCNConv(16, 7)
#)
可视化图嵌入(只有正向传播)
我是记着写这篇文章在4月。7月重新跑了一下,代码抛出一些错误,但是不会影响运行。第一次跑的时候没错误,真实奇怪,应该是安装了杂七杂八的库破环运行环境。
model=GCN(hidden_channels=16)
model.eval()
out=model(data.x,data.edge_index)
visualize(out,color=data.y)
进行训练得出结果
model=GCN(hidden_channels=16)
optimizer=torch.optim.Adam(model.parameters(),lr=0.01,weight_decay=5e-4)
criterion=torch.nn.CrossEntropyLoss()
def train():
model.train()
optimizer.zero_grad()
out=model(data.x, data.edge_index)
loss=criterion(out[data.train_mask],data.y[data.train_mask])
loss.backward()
optimizer.step()
return loss
def test():
model.eval()
out=model(data.x,data.edge_index)
pred=out.argmax(dim=1)
test_correct=pred[data.test_mask]==data.y[data.test_mask]
test_acc=int(test_correct.sum())/int(data.test_mask.sum())
return test_acc
for epoch in range(1,101):
loss=train()
print(f'Epoch: {epoch:03d}, Loss: {loss:.4f}')
#这里就不展示输出
test_acc=test()
print(f'Test Accuracy: {test_acc:.4f}')
#输出:Test Accuracy: 0.8170
可视化图嵌入(训练过后)
代码实操2:GCN的简单实现
这是PYG官方文档的代码,就以难度而言其实就是少了可视化的东西。构建GCN的框架不同,使用损失函数不同。文章来源:https://www.toymoban.com/news/detail-453885.html
from torch_geometric.datasets import Planetoid
from torch_geometric.nn import GCNConv
import torch.nn.functional as F
import torch
class GCN(torch.nn.Module):
def __init__(self):
super().__init__()
self.conv1=GCNConv(dataset.num_node_features,16)
self.conv2=GCNConv(16,dataset.num_classes)
def forward(self,data):
x,edge_index=data.x,data.edge_index
x=self.conv1(x,edge_index)
x=F.relu(x)
x=F.dropout(x,training=self.training)
x=self.conv2(x,edge_index)
return F.log_softmax(x,dim=1)
dataset=Planetoid(root='C:/Users/19216/Desktop/project/Project1/Node_Classification2/Planetoid',name='Cora')
device=torch.device('cuda' if torch.cuda.is_available() else 'cpu')
model=GCN().to(device)
data=dataset[0].to(device)
optimizer=torch.optim.Adam(model.parameters(),lr=0.01,weight_decay=5e-4)
model.train()
for epoch in range(200):
optimizer.zero_grad()
out=model(data)
loss=F.nll_loss(out[data.train_mask],data.y[data.train_mask])
loss.backward()
optimizer.step()
model.eval()
pred=model(data).argmax(dim=1)
correct=(pred[data.test_mask]==data.y[data.test_mask]).sum()
acc=int(correct)/int(data.test_mask.sum())
print(f'Accuracy: {acc:.4f}')
#输出:Accuracy: 0.8090
代码实操3:GAT的简单实现
这里操作同上,代码略有不同。文章来源地址https://www.toymoban.com/news/detail-453885.html
from torch_geometric.datasets import Planetoid
from torch_geometric.nn import GATConv
import torch.nn.functional as F
import torch
class GCN(torch.nn.Module):
def __init__(self):
super().__init__()
self.conv1=GATConv(dataset.num_node_features,16)
self.conv2=GATConv(16,dataset.num_classes)
def forward(self,data):
x,edge_index=data.x,data.edge_index
x=F.dropout(x,p=0.6,training=self.training)
x=self.conv1(x,edge_index)
x=F.relu(x)
x=F.dropout(x,p=0.6,training=self.training)
x=self.conv2(x,edge_index)
return x
dataset=Planetoid(root='C:/Users/19216/Desktop/project/Project1/Node_Classification2/Planetoid',name='Cora')
device=torch.device('cuda' if torch.cuda.is_available() else 'cpu');model=GCN().to(device);data=dataset[0].to(device)
optimizer=torch.optim.Adam(model.parameters(),lr=0.05,weight_decay=5e-4);criterion=torch.nn.CrossEntropyLoss()
model.train()
for epoch in range(200):
optimizer.zero_grad()
out=model(data)
loss=criterion(out[data.train_mask],data.y[data.train_mask])
loss.backward()
optimizer.step()
model.eval()
pred=model(data).argmax(dim=1);correct=(pred[data.test_mask]==data.y[data.test_mask]).sum();acc=int(correct)/int(data.test_mask.sum())
print(f'Accuracy: {acc:.4f}')
#输出:Accuracy: 0.7980
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