pytorch识别手写数字代码

时间: 2023-02-28 07:22:24 浏览: 70
我可以提供一个示例代码,它可以帮助您识别手写数字:import torch import torch.nn as nn import torch.optim as optim import torchvision from torchvision import datasets, transforms# Download and load the data train_dataset = datasets.MNIST(root='./dataset', train=True, download=True, transform=transforms.ToTensor()) test_dataset = datasets.MNIST(root='./dataset', train=False, download=True, transform=transforms.ToTensor())# Create a model model = nn.Sequential( nn.Linear(784, 128), nn.ReLU(), nn.Linear(128, 64), nn.ReLU(), nn.Linear(64, 10) )# Define the loss and the optimizer criterion = nn.CrossEntropyLoss() optimizer = optim.SGD(model.parameters(), lr=0.01)# Train the model num_epochs = 10 for epoch in range(num_epochs): train_loss = 0.0 for images, labels in train_dataset: optimizer.zero_grad() outputs = model(images.view(images.shape[0], -1)) loss = criterion(outputs, labels) loss.backward() optimizer.step() train_loss += loss.item() print('Epoch [{}/{}], Train Loss: {:.4f}'.format(epoch+1, num_epochs, train_loss/len(train_dataset)))# Test the model correct = 0 total = 0 with torch.no_grad(): for images, labels in test_dataset: outputs = model(images.view(images.shape[0], -1)) _, predicted = torch.max(outputs.data, 1) total += labels.size(0) correct += (predicted == labels).sum()print('Accuracy of the model on the 10000 test images: {} %'.format(100 * correct / total))

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好的,以下是一个简单的PyTorch手写数字识别代码: python import torch import torch.nn as nn import torch.optim as optim import torchvision.datasets as datasets import torchvision.transforms as transforms # 定义网络结构 class Net(nn.Module): def __init__(self): super(Net, self).__init__() self.conv1 = nn.Conv2d(1, 10, kernel_size=5) self.conv2 = nn.Conv2d(10, 20, kernel_size=5) self.fc1 = nn.Linear(320, 50) self.fc2 = nn.Linear(50, 10) def forward(self, x): x = nn.functional.relu(nn.functional.max_pool2d(self.conv1(x), 2)) x = nn.functional.relu(nn.functional.max_pool2d(self.conv2(x), 2)) x = x.view(-1, 320) x = nn.functional.relu(self.fc1(x)) x = self.fc2(x) return nn.functional.log_softmax(x, dim=1) # 加载数据集 train_dataset = datasets.MNIST(root='./data', train=True, transform=transforms.ToTensor(), download=True) test_dataset = datasets.MNIST(root='./data', train=False, transform=transforms.ToTensor()) # 定义训练参数 batch_size = 64 learning_rate = 0.01 momentum = 0.5 epochs = 10 # 加载数据集 train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=batch_size, shuffle=True) test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=batch_size, shuffle=False) # 定义模型和优化器 model = Net() optimizer = optim.SGD(model.parameters(), lr=learning_rate, momentum=momentum) # 训练模型 for epoch in range(epochs): for batch_idx, (data, target) in enumerate(train_loader): optimizer.zero_grad() output = model(data) loss = nn.functional.nll_loss(output, target) loss.backward() optimizer.step() if batch_idx % 100 == 0: print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}'.format( epoch, batch_idx * len(data), len(train_loader.dataset), 100. * batch_idx / len(train_loader), loss.item())) # 测试模型 model.eval() test_loss = 0 correct = 0 with torch.no_grad(): for data, target in test_loader: output = model(data) test_loss += nn.functional.nll_loss(output, target, size_average=False).item() pred = output.argmax(dim=1, keepdim=True) correct += pred.eq(target.view_as(pred)).sum().item() test_loss /= len(test_loader.dataset) print('\nTest set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)\n'.format( test_loss, correct, len(test_loader.dataset), 100. * correct / len(test_loader.dataset))) 这个代码使用了PyTorch深度学习框架来训练一个手写数字识别模型。我们使用了MNIST数据集,它包含了大量的手写数字图像和对应的标签。我们定义了一个卷积神经网络模型,使用了两个卷积层和两个全连接层。我们使用SGD优化器来训练模型,并使用nll_loss()方法来计算损失。最后,我们使用argmax()方法来预测测试集,并使用sum()方法来计算准确率。
好的,以下是一段 PyTorch 实现的手写数字识别的代码: python import torch import torch.nn as nn import torch.nn.functional as F import torch.optim as optim from torchvision import datasets, transforms # 定义网络结构 class Net(nn.Module): def __init__(self): super(Net, self).__init__() self.conv1 = nn.Conv2d(1, 20, 5, 1) self.conv2 = nn.Conv2d(20, 50, 5, 1) self.fc1 = nn.Linear(4*4*50, 500) self.fc2 = nn.Linear(500, 10) def forward(self, x): x = F.relu(self.conv1(x)) x = F.max_pool2d(x, 2, 2) x = F.relu(self.conv2(x)) x = F.max_pool2d(x, 2, 2) x = x.view(-1, 4*4*50) x = F.relu(self.fc1(x)) x = self.fc2(x) return F.log_softmax(x, dim=1) # 加载数据集,进行数据预处理 transform = transforms.Compose([ transforms.ToTensor(), transforms.Normalize((0.1307,), (0.3081,)) ]) train_dataset = datasets.MNIST('~/pytorch_data/mnist/', train=True, download=True, transform=transform) test_dataset = datasets.MNIST('~/pytorch_data/mnist/', train=False, download=True, transform=transform) train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=64, shuffle=True) test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=64, shuffle=False) # 初始化网络,定义损失函数和优化器 model = Net() criterion = nn.CrossEntropyLoss() optimizer = optim.SGD(model.parameters(), lr=0.01, momentum=0.5) # 训练网络 for epoch in range(10): running_loss = 0.0 for i, data in enumerate(train_loader, 0): inputs, labels = data optimizer.zero_grad() outputs = model(inputs) loss = criterion(outputs, labels) loss.backward() optimizer.step() running_loss += loss.item() if i % 2000 == 1999:
我可以回答这个问题。以下是一个使用 PyTorch 实现手写数字识别 MNIST 数据集的代码示例: import torch import torch.nn as nn import torch.optim as optim import torchvision.datasets as datasets import torchvision.transforms as transforms # 定义神经网络模型 class Net(nn.Module): def __init__(self): super(Net, self).__init__() self.conv1 = nn.Conv2d(1, 32, kernel_size=3) self.conv2 = nn.Conv2d(32, 64, kernel_size=3) self.dropout1 = nn.Dropout2d(0.25) self.dropout2 = nn.Dropout2d(0.5) self.fc1 = nn.Linear(9216, 128) self.fc2 = nn.Linear(128, 10) def forward(self, x): x = self.conv1(x) x = nn.functional.relu(x) x = self.conv2(x) x = nn.functional.relu(x) x = nn.functional.max_pool2d(x, 2) x = self.dropout1(x) x = torch.flatten(x, 1) x = self.fc1(x) x = nn.functional.relu(x) x = self.dropout2(x) x = self.fc2(x) output = nn.functional.log_softmax(x, dim=1) return output # 加载数据集 train_dataset = datasets.MNIST(root='./data', train=True, download=True, transform=transforms.ToTensor()) test_dataset = datasets.MNIST(root='./data', train=False, download=True, transform=transforms.ToTensor()) # 定义训练参数 batch_size = 64 learning_rate = 0.01 momentum = 0.5 # 定义优化器和损失函数 model = Net() optimizer = optim.SGD(model.parameters(), lr=learning_rate, momentum=momentum) criterion = nn.CrossEntropyLoss() # 训练模型 train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=batch_size, shuffle=True) test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=batch_size, shuffle=False) epochs = 10 for epoch in range(epochs): model.train() for batch_idx, (data, target) in enumerate(train_loader): optimizer.zero_grad() output = model(data) loss = criterion(output, target) loss.backward() optimizer.step() model.eval() test_loss = 0 correct = 0 with torch.no_grad(): for data, target in test_loader: output = model(data) test_loss += criterion(output, target).item() pred = output.argmax(dim=1, keepdim=True) correct += pred.eq(target.view_as(pred)).sum().item() test_loss /= len(test_loader.dataset) accuracy = 100. * correct / len(test_loader.dataset) print('Epoch: {}, Test set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)'.format( epoch, test_loss, correct, len(test_loader.dataset), accuracy)) 这个代码实现了一个卷积神经网络,用于对 MNIST 数据集中的手写数字进行分类。训练过程中使用了随机梯度下降优化器和交叉熵损失函数。在训练结束后,输出了测试集上的平均损失和准确率。
很抱歉,根据提供的引用内容,没有提到PyTorch的LeNet手写数字识别代码。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LeNet网络结构 class LeNet(nn.Module): def __init__(self): super(LeNet, self).__init__() self.conv1 = nn.Conv2d(1, 6, kernel_size=5) self.pool1 = nn.MaxPool2d(kernel_size=2) self.conv2 = nn.Conv2d(6, 16, kernel_size=5) self.pool2 = nn.MaxPool2d(kernel_size=2) self.fc1 = nn.Linear(16 * 4 * 4, 120) self.fc2 = nn.Linear(120, 84) self.fc3 = nn.Linear(84, 10) def forward(self, x): x = self.pool1(torch.relu(self.conv1(x))) x = self.pool2(torch.relu(self.conv2(x))) x = x.view(-1, 16 * 4 * 4) x = torch.relu(self.fc1(x)) x = torch.relu(self.fc2(x)) x = self.fc3(x) return x # 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) # 定义训练参数 batch_size = 64 learning_rate = 0.01 num_epochs = 10 # 定义数据加载器 train_loader = torch.utils.data.DataLoader(dataset=train_dataset, batch_size=batch_size, shuffle=True) test_loader = torch.utils.data.DataLoader(dataset=test_dataset, batch_size=batch_size, shuffle=False) # 定义模型、损失函数和优化器 model = LeNet() criterion = nn.CrossEntropyLoss() optimizer = optim.SGD(model.parameters(), lr=learning_rate) # 训练模型 for epoch in range(num_epochs): for i, (images, labels) in enumerate(train_loader): optimizer.zero_grad() outputs = model(images) loss = criterion(outputs, labels) loss.backward() optimizer.step() if (i+1) % 100 == 0: print('Epoch [{}/{}], Step [{}/{}], Loss: {:.4f}'.format(epoch+1, num_epochs, i+1, len(train_loader), loss.item())) # 测试模型 with torch.no_grad(): correct = 0 total = 0 for images, labels in test_loader: outputs = model(images) _, predicted = torch.max(outputs.data, 1) total += labels.size(0) correct += (predicted == labels).sum().item() print('Test Accuracy of the model on the 10000 test images: {} %'.format(100 * correct / total))
很高兴回答您的问题。下面是基于PyTorch实现的MNIST手写数字识别代码示例: 首先,我们需要导入所需的 Python 库: python import torch import torch.nn as nn import torch.optim as optim from torch.utils.data import DataLoader from torchvision import datasets, transforms 接着,我们可以定义一些超参数: python batch_size = 64 learning_rate = 0.01 epochs = 10 然后,我们可以对数据进行预处理: python transform = transforms.Compose([ transforms.ToTensor(), transforms.Normalize((0.1307,), (0.3081,)) ]) train_dataset = datasets.MNIST( root='./data', train=True, download=True, transform=transform) test_dataset = datasets.MNIST( root='./data', train=False, download=True, transform=transform) train_loader = DataLoader(train_dataset, batch_size=batch_size, shuffle=True) test_loader = DataLoader(test_dataset, batch_size=batch_size, shuffle=True) 接下来,我们可以构建模型: python class Net(nn.Module): def __init__(self): super().__init__() self.conv1 = nn.Conv2d(1, 32, kernel_size=5) self.conv2 = nn.Conv2d(32, 64, kernel_size=5) self.fc1 = nn.Linear(1024, 128) self.fc2 = nn.Linear(128, 10) def forward(self, x): x = nn.functional.relu(nn.functional.max_pool2d(self.conv1(x), 2)) x = nn.functional.relu(nn.functional.max_pool2d(self.conv2(x), 2)) x = x.view(-1, 1024) x = nn.functional.relu(self.fc1(x)) x = self.fc2(x) return nn.functional.log_softmax(x, dim=1) model = Net() 接着,我们可以定义损失函数和优化器: python criterion = nn.CrossEntropyLoss() optimizer = optim.SGD(model.parameters(), lr=learning_rate, momentum=0.5) 最后,我们可以训练模型: python for epoch in range(epochs): for batch_idx, (data, target) in enumerate(train_loader): optimizer.zero_grad() output = model(data) loss = criterion(output, target) loss.backward() optimizer.step() if batch_idx % 250 == 0: print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}'.format( epoch, batch_idx * len(data), len(train_loader.dataset), 100. * batch_idx / len(train_loader), loss.item())) test_loss = 0 correct = 0 with torch.no_grad(): for data, target in test_loader: output = model(data) test_loss += criterion(output, target).item() pred = output.argmax(dim=1, keepdim=True) correct += pred.eq(target.view_as(pred)).sum().item() test_loss /= len(test_loader.dataset) print('\nTest set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)\n'.format( test_loss, correct, len(test_loader.dataset), 100. * correct / len(test_loader.dataset))) 希望这段代码可以帮助您实现基于 PyTorch 的手写数字识别模型。如果您有任何问题或疑问,请随时提出。
要实现手写数字识别,可以使用PyTorch框架。以下是一个简单的实现步骤: 1. 准备数据集:可以使用MNIST数据集,其中包含了大量的手写数字图片和对应的标签。 2. 定义模型:可以使用卷积神经网络(CNN)来实现手写数字识别。在PyTorch中,可以使用nn.Module来定义模型。 3. 定义损失函数:可以使用交叉熵损失函数来计算模型预测结果与真实标签之间的差异。 4. 定义优化器:可以使用随机梯度下降(SGD)优化器来更新模型参数。 5. 训练模型:将数据集分为训练集和测试集,使用训练集对模型进行训练,并使用测试集对模型进行评估。 6. 预测结果:使用训练好的模型对新的手写数字图片进行预测。 以下是一个简单的代码示例: python import torch import torch.nn as nn import torch.optim as optim from torchvision import datasets, transforms # 准备数据集 transform = transforms.Compose([ transforms.ToTensor(), transforms.Normalize((0.1307,), (0.3081,)) ]) train_dataset = datasets.MNIST('data', train=True, download=True, transform=transform) test_dataset = datasets.MNIST('data', train=False, download=True, transform=transform) train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=64, shuffle=True) test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=64, shuffle=True) # 定义模型 class Net(nn.Module): def __init__(self): super(Net, self).__init__() self.conv1 = nn.Conv2d(1, 10, kernel_size=5) self.conv2 = nn.Conv2d(10,20, kernel_size=5) self.fc1 = nn.Linear(320, 50) self.fc2 = nn.Linear(50, 10) def forward(self, x): x = nn.functional.relu(nn.functional.max_pool2d(self.conv1(x),2)) x = nn.functional.relu(nn.functional.max_pool2d(self.conv2(x), 2)) x = x.view(-1, 320) x = nn.functional.relu(self.fc1(x)) x = self.fc2(x) return nn.functional.log_softmax(x, dim=1) model = Net() # 定义损失函数和优化器 criterion = nn.CrossEntropyLoss() optimizer = optim.SGD(model.parameters(), lr=0.01, momentum=0.5) # 训练模型 def train(epoch): model.train() for batch_idx, (data, target) in enumerate(train_loader): optimizer.zero_grad() output = model(data) loss = criterion(output, target) loss.backward() optimizer.step() if batch_idx % 10 == 0: print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}'.format( epoch, batch_idx * len(data), len(train_loader.dataset), 100. * batch_idx / len(train_loader), loss.item())) def test(): model.eval() test_loss = 0 correct = 0 with torch.no_grad(): for data, target in test_loader: output = model(data) test_loss += criterion(output, target).item() pred = output.argmax(dim=1, keepdim=True) correct += pred.eq(target.view_as(pred)).sum().item() test_loss /= len(test_loader.dataset) print('Test set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)'.format( test_loss, correct, len(test_loader.dataset), 100. * correct / len(test_loader.dataset))) for epoch in range(1, 11): train(epoch) test() # 预测结果 def predict(image): model.eval() with torch.no_grad(): output = model(image) pred = output.argmax(dim=1, keepdim=True) return pred.item() image = torch.randn(1, 1, 28, 28) print(predict(image))
可以使用PyTorch框架实现手写数字识别。具体步骤如下: 1. 准备数据集:手写数字识别数据集包括MNIST和Fashion-MNIST等。可以使用PyTorch提供的torchvision库中的datasets来加载数据集。 2. 定义模型:可以使用卷积神经网络(CNN)来实现手写数字识别。在PyTorch中可以使用nn模块进行模型的定义。 3. 训练模型:使用PyTorch中的优化器(如SGD、Adam等)和损失函数(如交叉熵损失函数)来训练模型。可以使用PyTorch提供的DataLoader来进行数据的批量读取。 4. 测试模型:使用测试集对训练好的模型进行测试,评估模型的识别准确率。 下面是一个简单的示例代码: import torch import torch.nn as nn import torch.optim as optim import torchvision.datasets as datasets import torchvision.transforms as transforms # 定义模型 class Net(nn.Module): def __init__(self): super(Net, self).__init__() self.conv1 = nn.Conv2d(1, 10, kernel_size=5) self.conv2 = nn.Conv2d(10, 20, kernel_size=5) self.fc1 = nn.Linear(320, 50) self.fc2 = nn.Linear(50, 10) def forward(self, x): x = nn.functional.relu(nn.functional.max_pool2d(self.conv1(x), 2)) x = nn.functional.relu(nn.functional.max_pool2d(self.conv2(x), 2)) x = x.view(-1, 320) x = nn.functional.relu(self.fc1(x)) x = self.fc2(x) return nn.functional.log_softmax(x, dim=1) # 加载数据集 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) # 定义数据加载器 train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=64, shuffle=True) test_loader = torch.utils.data.DataLoader(test_dataset, batch_size=64, shuffle=False) # 定义模型、优化器和损失函数 model = Net() optimizer = optim.SGD(model.parameters(), lr=0.01, momentum=0.5) criterion = nn.CrossEntropyLoss() # 训练模型 for epoch in range(10): for batch_idx, (data, target) in enumerate(train_loader): optimizer.zero_grad() output = model(data) loss = criterion(output, target) loss.backward() optimizer.step() # 测试模型 correct = 0 total = 0 with torch.no_grad(): for batch_idx, (data, target) in enumerate(test_loader): output = model(data) _, predicted = torch.max(output.data, 1) total += target.size(0) correct += (predicted == target).sum().item() print('Accuracy: %f %%' % (100 * correct / total)) 以上代码实现了一个简单的手写数字识别模型,使用了MNIST数据集进行训练和测试。在训练10个epoch后,该模型在测试集上的识别准确率可达到97%左右。
以下是一个基于PyTorch的手写数字识别代码。这个代码使用的是一个基于MNIST数据集的卷积神经网络模型。 python import torch import torch.nn as nn import torch.optim as optim import torchvision.transforms as transforms from torchvision.datasets import MNIST from torch.utils.data import DataLoader # 定义卷积神经网络模型 class CNN(nn.Module): def __init__(self): super(CNN, self).__init__() self.layer1 = nn.Sequential( nn.Conv2d(1, 16, kernel_size=5, padding=2), nn.BatchNorm2d(16), nn.ReLU(), nn.MaxPool2d(2)) self.layer2 = nn.Sequential( nn.Conv2d(16, 32, kernel_size=5, padding=2), nn.BatchNorm2d(32), nn.ReLU(), nn.MaxPool2d(2)) self.fc = nn.Linear(7 * 7 * 32, 10) def forward(self, x): out = self.layer1(x) out = self.layer2(out) out = out.view(out.size(0), -1) out = self.fc(out) return out # 加载数据集 transform = transforms.Compose([ transforms.ToTensor(), transforms.Normalize((0.1307,), (0.3081,)) ]) train_data = MNIST(root='./data', train=True, transform=transform, download=True) train_loader = DataLoader(train_data, batch_size=100, shuffle=True) # 定义模型、损失函数和优化器 model = CNN() criterion = nn.CrossEntropyLoss() optimizer = optim.Adam(model.parameters(), lr=0.001) # 训练模型 for epoch in range(10): running_loss = 0.0 for i, (inputs, labels) in enumerate(train_loader): optimizer.zero_grad() outputs = model(inputs) loss = criterion(outputs, labels) loss.backward() optimizer.step() running_loss += loss.item() if (i+1) % 100 == 0: print('Epoch [%d/%d], Iter [%d/%d] Loss: %.4f' % (epoch+1, 10, i+1, len(train_data)//100, running_loss/100)) running_loss = 0.0 # 保存模型 torch.save(model.state_dict(), 'model.pth') 在训练完模型后,我们可以使用以下代码来测试我们的模型: python import torch import torchvision.transforms as transforms from PIL import Image # 加载模型 model = CNN() model.load_state_dict(torch.load('model.pth')) # 图像预处理 transform = transforms.Compose([ transforms.ToTensor(), transforms.Normalize((0.1307,), (0.3081,)) ]) # 加载测试图像 image_path = 'test_image.png' image = Image.open(image_path).convert('L') image = transform(image) image = image.unsqueeze(0) # 使用模型进行预测 output = model(image) _, predicted = torch.max(output.data, 1) # 输出预测结果 print('Predicted Digit:', predicted.item()) 在这个代码中,我们将一张手写数字的图像作为输入,使用我们训练好的模型来进行预测,并输出预测结果。
下面是一个简单的 PyTorch 实现 MNIST 手写数字识别的代码: python import torch import torch.nn as nn import torch.optim as optim import torchvision.datasets as datasets import torchvision.transforms as transforms # 定义超参数 batch_size = 64 learning_rate = 0.01 num_epochs = 10 # 下载和加载数据集 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) # 创建数据加载器 train_loader = torch.utils.data.DataLoader(dataset=train_dataset, batch_size=batch_size, shuffle=True) test_loader = torch.utils.data.DataLoader(dataset=test_dataset, batch_size=batch_size, shuffle=False) # 定义模型 class Net(nn.Module): def __init__(self): super(Net, self).__init__() self.conv1 = nn.Conv2d(1, 10, kernel_size=5) self.conv2 = nn.Conv2d(10, 20, kernel_size=5) self.pool = nn.MaxPool2d(2) self.fc = nn.Linear(320, 10) def forward(self, x): x = self.pool(nn.functional.relu(self.conv1(x))) x = self.pool(nn.functional.relu(self.conv2(x))) x = x.view(-1, 320) x = self.fc(x) return x # 实例化模型和损失函数 model = Net() criterion = nn.CrossEntropyLoss() # 使用随机梯度下降优化器 optimizer = optim.SGD(model.parameters(), lr=learning_rate) # 训练模型 for epoch in range(num_epochs): for i, (images, labels) in enumerate(train_loader): # 将数据加载到 GPU 中 images = images.cuda() labels = labels.cuda() # 前向传播和计算损失 outputs = model(images) loss = criterion(outputs, labels) # 反向传播和优化 optimizer.zero_grad() loss.backward() optimizer.step() # 每 100 个批次输出一次日志信息 if (i + 1) % 100 == 0: print('Epoch [{}/{}], Step [{}/{}], Loss: {:.4f}' .format(epoch + 1, num_epochs, i + 1, len(train_loader), loss.item())) # 测试模型 model.eval() with torch.no_grad(): correct = 0 total = 0 for images, labels in test_loader: # 将数据加载到 GPU 中 images = images.cuda() labels = labels.cuda() # 计算输出并获取预测结果 outputs = model(images) _, predicted = torch.max(outputs.data, 1) # 统计正确预测的数量 total += labels.size(0) correct += (predicted == labels).sum().item() print('Test Accuracy of the model on the 10000 test images: {} %'.format(100 * correct / total)) 这个代码使用了一个简单的卷积神经网络,包括两个卷积层、两个最大池化层和一个全连接层。训练过程中使用随机梯度下降优化器,测试过程中计算模型的准确率。
你好,以下是mnist手写数字识别的PyTorch代码: import torch import torchvision import torchvision.transforms as transforms import torch.nn as nn import torch.nn.functional as F import torch.optim as optim # 定义数据预处理 transform = transforms.Compose( [transforms.ToTensor(), transforms.Normalize((.5,), (.5,))]) # 加载数据集 trainset = torchvision.datasets.MNIST(root='./data', train=True, download=True, transform=transform) trainloader = torch.utils.data.DataLoader(trainset, batch_size=4, shuffle=True, num_workers=2) testset = torchvision.datasets.MNIST(root='./data', train=False, download=True, transform=transform) testloader = torch.utils.data.DataLoader(testset, batch_size=4, shuffle=False, num_workers=2) # 定义神经网络 class Net(nn.Module): def __init__(self): super(Net, self).__init__() self.conv1 = nn.Conv2d(1, 6, 5) self.pool = nn.MaxPool2d(2, 2) self.conv2 = nn.Conv2d(6, 16, 5) self.fc1 = nn.Linear(16 * 4 * 4, 120) self.fc2 = nn.Linear(120, 84) self.fc3 = nn.Linear(84, 10) def forward(self, x): x = self.pool(F.relu(self.conv1(x))) x = self.pool(F.relu(self.conv2(x))) x = x.view(-1, 16 * 4 * 4) x = F.relu(self.fc1(x)) x = F.relu(self.fc2(x)) x = self.fc3(x) return x net = Net() # 定义损失函数和优化器 criterion = nn.CrossEntropyLoss() optimizer = optim.SGD(net.parameters(), lr=.001, momentum=.9) # 训练网络 for epoch in range(2): # 多次循环数据集 running_loss = . for i, data in enumerate(trainloader, ): # 获取输入 inputs, labels = data # 梯度清零 optimizer.zero_grad() # 正向传播,反向传播,优化 outputs = net(inputs) loss = criterion(outputs, labels) loss.backward() optimizer.step() # 打印统计信息 running_loss += loss.item() if i % 200 == 1999: # 每200个小批量数据打印一次 print('[%d, %5d] loss: %.3f' % (epoch + 1, i + 1, running_loss / 200)) running_loss = . print('Finished Training') # 测试网络 correct = total = with torch.no_grad(): for data in testloader: images, labels = data outputs = net(images) _, predicted = torch.max(outputs.data, 1) total += labels.size() correct += (predicted == labels).sum().item() print('Accuracy of the network on the 10000 test images: %d %%' % ( 100 * correct / total)) 希望对你有所帮助!
为了进行PyTorch手写数字识别预测类别,我们可以使用线性回归模型。在这个模型中,我们首先需要加载手写数字识别数据集,并将数据集分为训练集和测试集。接下来,我们可以定义一个网络结构,该网络结构包含一个线性层和一个softmax层。然后,我们使用训练集对模型进行训练,并使用测试集对模型进行评估。 在评估过程中,我们通过模型运行测试集中的每个图像,并将模型输出的数字作为预测结果。然后,我们计算预测结果正确的数量,并将其除以测试集的总数量,得到预测的准确率。 下面是一个示例代码,展示了如何使用PyTorch进行手写数字识别预测类别: python import torch from torchvision import datasets, transforms from torch.utils.data import DataLoader from tqdm import tqdm # 加载手写数字识别数据集 transform = transforms.Compose([transforms.ToTensor(), transforms.Normalize((0.5,), (0.5,))]) mnist_test = datasets.MNIST(root='./data', train=False, download=True, transform=transform) test_loader = DataLoader(mnist_test, batch_size=64, shuffle=False) # 定义网络结构 W = torch.randn(784, 10) # 权重矩阵 b = torch.randn(10) # 偏置向量 #评估模型 correct = 0 total = len(mnist_test) with torch.no_grad(): # 遍历测试集的小批量数据 for images, labels in tqdm(test_loader): # 前向传播 x = images.view(-1, 28*28) y = torch.matmul(x, W) + b predictions = torch.argmax(y, dim=1) # 统计预测结果正确的数量 correct += torch.sum((predictions == labels).float()) # 计算准确率 accuracy = correct / total print('Test accuracy: {}'.format(accuracy)) 在上述代码中,我们首先导入所需的库,并定义了一个数据转换流程,用于将数据转换为张量并进行归一化处理。然后,我们加载手写数字识别数据集,并将其分批次加载到数据加载器中。接下来,我们定义了网络模型的参数W和b。在评估过程中,我们使用torch.no_grad()来关闭梯度计算,加快评估速度。最后,我们计算预测准确率并输出结果。 请注意,上述代码只是一个示例,实际情况中可能需要根据具体情况进行调整和修改。123 #### 引用[.reference_title] - *1* *3* [pytorch-简单回归问题-手写数字识别](https://blog.csdn.net/qq_44653420/article/details/130984978)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v93^chatsearchT3_2"}}] [.reference_item style="max-width: 50%"] - *2* [基于 PyTorch 的手写数字分类](https://blog.csdn.net/weixin_38739735/article/details/117971150)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v93^chatsearchT3_2"}}] [.reference_item style="max-width: 50%"] [ .reference_list ]
对于手写体数字识别MNIST问题,您可以使用PyTorch来实现。以下是一个简单的代码示例: 首先,导入所需的库: import torch import torch.nn as nn import torchvision import torchvision.transforms as transforms 接下来,定义超参数: input_size = 784 hidden_size = 100 num_classes = 10 num_epochs = 5 batch_size = 100 learning_rate = 0.001 然后,加载并预处理数据集: train_dataset = torchvision.datasets.MNIST(root='./data', train=True, transform=transforms.ToTensor(), download=True) test_dataset = torchvision.datasets.MNIST(root='./data', train=False, transform=transforms.ToTensor()) train_loader = torch.utils.data.DataLoader(dataset=train_dataset, batch_size=batch_size, shuffle=True) test_loader = torch.utils.data.DataLoader(dataset=test_dataset, batch_size=batch_size, shuffle=False) 定义神经网络模型: class NeuralNet(nn.Module): def __init__(self, input_size, hidden_size, num_classes): super(NeuralNet, self).__init__() self.fc1 = nn.Linear(input_size, hidden_size) self.relu = nn.ReLU() self.fc2 = nn.Linear(hidden_size, num_classes) def forward(self, x): out = self.fc1(x) out = self.relu(out) out = self.fc2(out) return out model = NeuralNet(input_size, hidden_size, num_classes) 定义损失函数和优化器: criterion = nn.CrossEntropyLoss() optimizer = torch.optim.Adam(model.parameters(), lr=learning_rate) 训练模型: total_step = len(train_loader) for epoch in range(num_epochs): for i, (images, labels) in enumerate(train_loader): images = images.reshape(-1, 28*28) # 前向传播 outputs = model(images) loss = criterion(outputs, labels) # 反向传播和优化 optimizer.zero_grad() loss.backward() optimizer.step() if (i+1) % 100 == 0: print ('Epoch [{}/{}], Step [{}/{}], Loss: {:.4f}' .format(epoch+1, num_epochs, i+1, total_step, loss.item())) 在测试集上评估模型: model.eval() with torch.no_grad(): correct = 0 total = 0 for images, labels in test_loader: images = images.reshape(-1, 28*28) outputs = model(images) _, predicted = torch.max(outputs.data, 1) total += labels.size(0) correct += (predicted == labels).sum().item() print('准确率: {} %'.format(100 * correct / total)) 这是一个简单的PyTorch实现手写体数字识别MNIST的示例。您可以根据需要进行进一步的调整和改进。
以下是使用PyTorch实现手写数字识别激活函数的示例代码: python import torch import torchvision import torchvision.transforms as transforms import torch.nn as nn import torch.optim as optim # 定义数据预处理 transform = transforms.Compose( [transforms.ToTensor(), transforms.Normalize((0.5,), (0.5,))]) # 加载训练集和测试集 trainset = torchvision.datasets.MNIST(root='./data', train=True, download=True, transform=transform) trainloader = torch.utils.data.DataLoader(trainset, batch_size=64, shuffle=True, num_workers=2) testset = torchvision.datasets.MNIST(root='./data', train=False, download=True, transform=transform) testloader = torch.utils.data.DataLoader(testset, batch_size=64, shuffle=False, num_workers=2) # 定义神经网络模型 class Net(nn.Module): def __init__(self): super(Net, self).__init__() self.conv1 = nn.Conv2d(1, 6, 5) self.pool = nn.MaxPool2d(2, 2) self.conv2 = nn.Conv2d(6, 16, 5) self.fc1 = nn.Linear(16 * 4 * 4, 120) self.fc2 = nn.Linear(120, 84) self.fc3 = nn.Linear(84, 10) def forward(self, x): x = self.pool(nn.functional.relu(self.conv1(x))) x = self.pool(nn.functional.relu(self.conv2(x))) x = x.view(-1, 16 * 4 * 4) x = nn.functional.relu(self.fc1(x)) x = nn.functional.relu(self.fc2(x)) x = self.fc3(x) return x net = Net() # 定义损失函数和优化器 criterion = nn.CrossEntropyLoss() optimizer = optim.SGD(net.parameters(), lr=0.001, momentum=0.9) # 训练神经网络 for epoch in range(10): # 训练数据集迭代10次 running_loss = 0.0 for i, data in enumerate(trainloader, 0): inputs, labels = data optimizer.zero_grad() outputs = net(inputs) loss = criterion(outputs, labels) loss.backward() optimizer.step() running_loss += loss.item() if i % 100 == 99: # 每100个小批量数据输出一次损失值 print('[%d, %5d] loss: %.3f' % (epoch + 1, i + 1, running_loss / 100)) running_loss = 0.0 # 测试神经网络 correct = 0 total = 0 with torch.no_grad(): for data in testloader: images, labels = data outputs = net(images) _, predicted = torch.max(outputs.data, 1) total += labels.size(0) correct += (predicted == labels).sum().item() print('Accuracy of the network on the 10000 test images: %d %%' % ( 100 * correct / total)) 在上述代码中,使用了ReLU作为神经网络的激活函数。具体地,在forward函数中,使用nn.functional.relu函数对卷积层和全连接层的输出进行激活。可以尝试使用其他激活函数,比如sigmoid和tanh,并观察它们的性能和效果。

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