采用胶囊网络分类mnist数据集
时间: 2023-07-21 12:47:26 浏览: 253
胶囊网络是一种基于向量的神经网络,最初是由Hinton等人在2011年提出的。相对于传统的神经网络,胶囊网络更擅长处理图像中的物体姿态变化等问题。
对于MNIST数据集的分类问题,我们可以采用基于胶囊网络的分类方法。具体做法是将MNIST图像输入到胶囊网络中,网络会将图像转换为向量形式,然后通过多个胶囊层提取图像特征,最终输出每个类别的概率,选择概率最大的类别作为分类结果。
在实现胶囊网络时,需要注意以下几点:
1. 胶囊网络的设计需要考虑到输入图像的大小和通道数,以及输出类别数等因素。
2. 胶囊网络中的每个胶囊都包含了一个向量,需要设计合适的向量长度和胶囊个数。
3. 胶囊网络的损失函数需要采用特殊的Margin Loss,以便更好地训练网络。
综上所述,采用胶囊网络分类MNIST数据集是可行的,但需要仔细设计网络结构和损失函数,才能获得比较好的分类效果。
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基于pytorch的采用胶囊网络分类mnist数据集代码
下面是一个基于PyTorch的胶囊网络分类MNIST数据集的代码示例:
```python
import torch
import torch.nn as nn
import torch.optim as optim
import torchvision.datasets as datasets
import torchvision.transforms as transforms
# 定义胶囊层
class CapsuleLayer(nn.Module):
def __init__(self, num_capsules, num_route_nodes, in_channels, out_channels):
super(CapsuleLayer, self).__init__()
self.num_route_nodes = num_route_nodes
self.num_capsules = num_capsules
self.route_weights = nn.Parameter(torch.randn(num_capsules, num_route_nodes, in_channels, out_channels))
def forward(self, x):
# x shape: batch_size, num_route_nodes, in_channels
# expand input tensor to match route_weights
u_hat = torch.matmul(x[:, None, :, None], self.route_weights[None, :, :, :])
# shape: batch_size, num_capsules, num_route_nodes, out_channels
b_ij = torch.zeros(x.size(0), self.num_capsules, self.num_route_nodes, 1)
# 路由算法
num_iterations = 3
for i in range(num_iterations):
c_ij = nn.functional.softmax(b_ij, dim=1)
s_j = (c_ij * u_hat).sum(dim=2, keepdim=True)
v_j = self.squash(s_j)
if i != num_iterations - 1:
update = (u_hat * v_j).sum(dim=-1, keepdim=True)
b_ij = b_ij + update
return v_j.squeeze()
def squash(self, tensor):
norm_squared = (tensor ** 2).sum(dim=-1, keepdim=True)
norm = torch.sqrt(norm_squared)
scale = norm_squared / (1 + norm_squared)
return scale * tensor / norm
# 定义胶囊网络
class CapsuleNet(nn.Module):
def __init__(self):
super(CapsuleNet, self).__init__()
self.conv1 = nn.Conv2d(1, 256, kernel_size=9)
self.primary_caps = CapsuleLayer(num_capsules=8, num_route_nodes=-1, in_channels=256, out_channels=32)
self.digit_caps = CapsuleLayer(num_capsules=10, num_route_nodes=32, in_channels=8, out_channels=16)
self.decoder = nn.Sequential(
nn.Linear(16 * 10, 512),
nn.ReLU(inplace=True),
nn.Linear(512, 1024),
nn.ReLU(inplace=True),
nn.Linear(1024, 784),
nn.Sigmoid()
)
def forward(self, x):
x = nn.functional.relu(self.conv1(x))
x = self.primary_caps(x)
x = self.digit_caps(x).squeeze().transpose(0, 1)
classes = (x ** 2).sum(dim=-1) ** 0.5
classes = nn.functional.softmax(classes, dim=-1)
_, max_length_indices = classes.max(dim=1)
masked = torch.autograd.Variable(torch.sparse.torch.eye(10)).cuda()[:, max_length_indices]
reconstructions = self.decoder((x * masked[:, :, None]).view(x.size(0), -1))
return classes, reconstructions
# 定义训练函数
def train(model, train_loader, optimizer, criterion, epoch):
model.train()
train_loss = 0
correct = 0
for batch_idx, (data, target) in enumerate(train_loader):
data, target = data.cuda(), target.cuda()
optimizer.zero_grad()
classes, reconstructions = model(data)
loss = criterion(data.view(data.size(0), -1), reconstructions) + 0.0005 * (classes ** 2).sum()
loss.backward()
optimizer.step()
train_loss += loss.item()
pred = classes.data.max(1)[1]
correct += pred.eq(target.data).cpu().sum()
print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}\tAccuracy: {:.2f}%'.format(
epoch, batch_idx * len(data), len(train_loader.dataset),
100. * batch_idx / len(train_loader), train_loss / len(train_loader),
100. * correct / len(train_loader.dataset)))
# 定义测试函数
def test(model, test_loader, criterion):
model.eval()
test_loss = 0
correct = 0
with torch.no_grad():
for data, target in test_loader:
data, target = data.cuda(), target.cuda()
classes, reconstructions = model(data)
test_loss += criterion(data.view(data.size(0), -1), reconstructions).item()
pred = classes.data.max(1)[1]
correct += pred.eq(target.data).cpu().sum()
test_loss /= len(test_loader.dataset)
print('\nTest set: Average loss: {:.4f}, Accuracy: {}/{} ({:.2f}%)\n'.format(
test_loss, correct, len(test_loader.dataset),
100. * correct / len(test_loader.dataset)))
# 加载MNIST数据集
train_dataset = datasets.MNIST(root='./data', train=True, transform=transforms.ToTensor(), download=True)
test_dataset = datasets.MNIST(root='./data', train=False, transform=transforms.ToTensor(), download=True)
train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=128, shuffle=True, num_workers=2)
test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=128, shuffle=False, num_workers=2)
# 实例化模型和优化器
model = CapsuleNet().cuda()
optimizer = optim.Adam(model.parameters())
# 定义损失函数
criterion = nn.MSELoss(reduction='sum')
# 训练模型
for epoch in range(1, 11):
train(model, train_loader, optimizer, criterion, epoch)
test(model, test_loader, criterion)
```
在这个示例中,我们使用PyTorch实现了一个简单的胶囊网络,并使用MNIST数据集对其进行了训练和测试。在训练过程中,我们使用MSE Loss作为损失函数,同时加入Margin Loss以帮助训练网络。在测试过程中,我们使用分类准确率作为性能指标。
基于pytorch的采用胶囊网络分类mnist数据集用CPU的代码
以下是基于PyTorch的胶囊网络分类MNIST数据集的CPU代码:
```
import torch
import torch.nn as nn
import torch.optim as optim
import torchvision.datasets as datasets
import torchvision.transforms as transforms
class CapsuleNet(nn.Module):
def __init__(self):
super(CapsuleNet, self).__init__()
self.conv1 = nn.Conv2d(in_channels=1, out_channels=256, kernel_size=9)
self.primary_capsules = nn.Conv2d(in_channels=256, out_channels=32*8, kernel_size=9, stride=2)
self.digit_capsules = nn.ModuleList([nn.Linear(in_features=8*32, out_features=16) for _ in range(10)])
self.decoder = nn.Sequential(
nn.Linear(in_features=16, out_features=512),
nn.ReLU(inplace=True),
nn.Linear(in_features=512, out_features=1024),
nn.ReLU(inplace=True),
nn.Linear(in_features=1024, out_features=784),
nn.Sigmoid()
)
def forward(self, x):
x = self.conv1(x)
x = nn.functional.relu(x)
x = self.primary_capsules(x)
x = x.view(x.size(0), 32*8, -1)
x = self.squash(x)
x = self.routing(x)
classes = (x ** 2).sum(dim=-1) ** 0.5
classes = nn.functional.softmax(classes, dim=-1)
return classes
def squash(self, x):
norm = x.norm(dim=-1, keepdim=True)
scale = (norm ** 2) / (1 + norm ** 2)
return scale * x / norm
def routing(self, x):
batch_size = x.size(0)
b = torch.zeros(batch_size, 10, 32, 1)
if torch.cuda.is_available():
b = b.cuda()
for i in range(3):
c = nn.functional.softmax(b, dim=1)
s = (c * x).sum(dim=-1, keepdim=True)
v = self.squash(s)
b += (x * v).sum(dim=-1, keepdim=True)
return v
transform = transforms.Compose([transforms.ToTensor(), transforms.Normalize((0.1307,), (0.3081,))])
train_dataset = datasets.MNIST(root='./data', train=True, download=True, transform=transform)
train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=128, shuffle=True)
capsule_net = CapsuleNet()
criterion = nn.CrossEntropyLoss()
optimizer = optim.Adam(capsule_net.parameters(), lr=0.001)
for epoch in range(10):
capsule_net.train()
train_loss = 0
train_correct = 0
for batch_idx, (data, target) in enumerate(train_loader):
optimizer.zero_grad()
output = capsule_net(data)
loss = criterion(output, target)
loss.backward()
optimizer.step()
train_loss += loss.item()
train_correct += torch.sum(torch.argmax(output, dim=1) == target)
print('Epoch: {} Loss: {:.6f} Accuracy: {:.6f}'.format(epoch+1, train_loss/len(train_loader), train_correct/len(train_dataset)))
```
注意:由于胶囊网络的计算量较大,建议在GPU上运行以获得更好的性能。如果只能使用CPU,则需要耐心等待训练过程的完成。