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import torch
import torch.nn as nn
import torch.nn.functional as F
from tqdm import tqdm
from torchvision import transforms
import torchvision
from torch.utils.data import DataLoader
transform = transforms.Compose([
transforms.Resize((512, 512)),
transforms.ToTensor(),
])
def make_dir(path):
import os
dir = os.path.exists(path)
if not dir:
os.makedirs(path)
make_dir('models')
batch_size = 8
train_set = torchvision.datasets.ImageFolder(root='data/cat_vs_dog/train', transform=transform)
train_loader = DataLoader(train_set, batch_size=batch_size, shuffle=True,
num_workers=0) # Batch Size定义：一次训练所选取的样本数。 Batch Size的大小影响模型的优化程度和速度。
val_dataset = torchvision.datasets.ImageFolder(root='data/cat_vs_dog/val', transform=transform)
val_loader = DataLoader(val_dataset, batch_size=batch_size, shuffle=True,
num_workers=0) # Batch Size定义：一次训练所选取的样本数。 Batch Size的大小影响模型的优化程度和速度。
device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
net = torchvision.models.resnet18(weights=True)
num_ftrs = net.fc.in_features
net.fc = nn.Linear(num_ftrs, 2) # 将输出维度修改为2
criterion = nn.CrossEntropyLoss()
net = net.to(device)
optimizer = torch.optim.Adam(lr=0.0001, params=net.parameters())
eposhs = 100
for epoch in range(eposhs):
print(f'--------------------{epoch}--------------------')
correct_train = 0
sum_loss_train = 0
total_correct_train = 0
for inputs, labels in tqdm(train_loader):
inputs = inputs.to(device)
labels = labels.to(device)
output = net(inputs)
loss = criterion(output, labels)
sum_loss_train = sum_loss_train + loss.item()
total_correct_train = total_correct_train + labels.size(0)
optimizer.zero_grad()
_, predicted = torch.max(output.data, 1)
loss.backward()
optimizer.step()
correct_train = correct_train + (predicted == labels).sum().item()
acc_train = correct_train / total_correct_train
print('训练准确率是{:.3f}%:'.format(acc_train*100) )
net.eval()
correct_val = 0
sum_loss_val = 0
total_correct_val = 0
for inputs, labels in tqdm(val_loader):
inputs = inputs.to(device)
labels = labels.to(device)
output = net(inputs)
loss = criterion(output, labels)
sum_loss_val = sum_loss_val + loss.item()
output = net(inputs)
total_correct_val = total_correct_val + labels.size(0)
optimizer.zero_grad()
_, predicted = torch.max(output.data, 1)
correct_val = correct_val + (predicted == labels).sum().item()
acc_val = correct_val / total_correct_val
print('验证准确率是{:.3f}%:'.format(acc_val*100) )
torch.save(net,'models/{}-{:.5f}_{:.3f}%_{:.5f}_{:.3f}%.pth'.format(epoch,sum_loss_train,acc_train *100,sum_loss_val,acc_val*100))
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