这部分是利用pytorch进行迁移学习，迁移的是VGG16
代码基于python3.7， pytorch 1.0，cuda 10.0 .
import torch
import torchvision
from torch.autograd import Variable
from torchvision import datasets, transforms, models
import os # os包集成了一些对文件路径和目录进行操作的类
import matplotlib.pyplot as plt
import time
# 读取数据
data_dir = 'DogsVSCats'
data_transform = {x:transforms.Compose([transforms.Scale([224, 224]),
transforms.ToTensor(),
transforms.Normalize(mean=[0.5,0.5,0.5],std=[0.5,0.5,0.5])
]) for x in ['train', 'valid']} # 这一步类似预处理,相比于手动搭建模型的方法，这里增加了预处理，图像大小为vgg的标准输入
image_datasets = {x:datasets.ImageFolder(root = os.path.join(data_dir,x),
transform = data_transform[x]) for x in ['train', 'valid']} # 这一步相当于读取数据
dataloader = {x:torch.utils.data.DataLoader(dataset = image_datasets[x],
batch_size = 16,
shuffle = True) for x in ['train', 'valid']} # 读取完数据后，对数据进行装载
e:\project3.7\lib\site-packages\torchvision\transforms\transforms.py:207: UserWarning: The use of the transforms.Scale transform is deprecated, please use transforms.Resize instead.
warnings.warn("The use of the transforms.Scale transform is deprecated, " +
model = models.vgg16(pretrained=True) # 调用Vgg16的预训练模型参数
print(model)
for parma in model.parameters():
parma.requires_grad = False # 冻结全部的梯度，使之梯度不进行更新
# 重新定义全连接层为我们想要的输出维度，进行二分类， 这里第一个全连接层的输入不应该对应是25088么？25088会报错？？修改后2048可以运行
# 这是因为开始的时候把图像裁剪到64*64导致的，标准vgg的输入是224*224的
model.classifier = torch.nn.Sequential(torch.nn.Linear(25088, 4096),
torch.nn.ReLU(),
torch.nn.Dropout(p = 0.5),
torch.nn.Linear(4096, 4096),
torch.nn.ReLU(),
torch.nn.Dropout(p = 0.5),
torch.nn.Linear(4096, 2))
print(model) # 打印改变后的模型进行对比
VGG(
(features): Sequential(
(0): Conv2d(3, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(1): ReLU(inplace)
(2): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(3): ReLU(inplace)
(4): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
(5): Conv2d(64, 128, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(6): ReLU(inplace)
(7): Conv2d(128, 128, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(8): ReLU(inplace)
(9): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
(10): Conv2d(128, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(11): ReLU(inplace)
(12): Conv2d(256, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(13): ReLU(inplace)
(14): Conv2d(256, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(15): ReLU(inplace)
(16): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
(17): Conv2d(256, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(18): ReLU(inplace)
(19): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(20): ReLU(inplace)
(21): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(22): ReLU(inplace)
(23): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
(24): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(25): ReLU(inplace)
(26): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(27): ReLU(inplace)
(28): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(29): ReLU(inplace)
(30): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
)
(avgpool): AdaptiveAvgPool2d(output_size=(7, 7))
(classifier): Sequential(
(0): Linear(in_features=25088, out_features=4096, bias=True)
(1): ReLU(inplace)
(2): Dropout(p=0.5)
(3): Linear(in_features=4096, out_features=4096, bias=True)
(4): ReLU(inplace)
(5): Dropout(p=0.5)
(6): Linear(in_features=4096, out_features=1000, bias=True)
)
)
VGG(
(features): Sequential(
(0): Conv2d(3, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(1): ReLU(inplace)
(2): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(3): ReLU(inplace)
(4): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
(5): Conv2d(64, 128, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(6): ReLU(inplace)
(7): Conv2d(128, 128, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(8): ReLU(inplace)
(9): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
(10): Conv2d(128, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(11): ReLU(inplace)
(12): Conv2d(256, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(13): ReLU(inplace)
(14): Conv2d(256, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(15): ReLU(inplace)
(16): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
(17): Conv2d(256, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(18): ReLU(inplace)
(19): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(20): ReLU(inplace)
(21): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(22): ReLU(inplace)
(23): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
(24): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(25): ReLU(inplace)
(26): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(27): ReLU(inplace)
(28): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
(29): ReLU(inplace)
(30): MaxPool2d(kernel_size=2, stride=2, padding=0, dilation=1, ceil_mode=False)
)
(avgpool): AdaptiveAvgPool2d(output_size=(7, 7))
(classifier): Sequential(
(0): Linear(in_features=25088, out_features=4096, bias=True)
(1): ReLU()
(2): Dropout(p=0.5)
(3): Linear(in_features=4096, out_features=4096, bias=True)
(4): ReLU()
(5): Dropout(p=0.5)
(6): Linear(in_features=4096, out_features=2, bias=True)
)
)
# 定义好模型的损失函数和对参数进行优化的优化函数
loss_f = torch.nn.CrossEntropyLoss()
optimizer = torch.optim.Adam(model.classifier.parameters(), lr=0.00001)
# 用cpu计算太慢了，改用GPU计算，model = model.cuda()和X, y = Variable(X.cuda()),
# Variable(y.cuda())就是参与迁移至GPUs的具体代码
print(torch.cuda.is_available())
Use_gpu = torch.cuda.is_available()
if Use_gpu:
model = model.cuda()
True
# 开始训练
epoch_n = 5
time_open = time.time()
for epoch in range(epoch_n):
print('Epoch {}/{}'.format(epoch, epoch_n - 1))
print('-' * 10)
for phase in ['train', 'valid']:
if phase == 'train':
print('Training...')
model.train(True)
else:
print('Validing...')
model.train(False)
running_loss = 0.0
running_correct = 0.0
for batch, data in enumerate(dataloader[phase], 1):
X, Y = data
if Use_gpu:
X, Y = Variable(X.cuda()), Variable(Y.cuda())
else:
X, Y = Variable(X), Variable(Y)
y_pred = model(X)
_, pred = torch.max(y_pred.data , 1) # 找出每一行中的最大的值对应的索引
optimizer.zero_grad()
loss = loss_f(y_pred, Y)
if phase == 'train':
loss.backward()
optimizer.step()
running_loss += loss.data.item()
running_correct += torch.sum(pred == Y.data)
if batch % 500 == 0 and phase == 'train':
print('Batch {}, Train Loss:{:.4f},Train ACC: {:.4f}'.format(batch,
running_loss / batch,
100 * running_correct / (16 * batch)))
epoch_loss = running_loss * 16 / len(image_datasets[phase])
epoch_acc = 100 * running_correct / len(image_datasets[phase])
print('{} Loss:{:.4f} ACC:{:.4f}%'.format(phase, epoch_loss, epoch_acc))
time_end = time.time() - time_open
print(time_end)
True
Epoch 0/4
Training…
Batch 500, Train Loss:0.1004,Train ACC: 96.0000
Batch 1000, Train Loss:0.0789,Train ACC: 97.0000
train Loss:0.0710 ACC:97.0000%
Validing…
valid Loss:0.0557 ACC:98.0000%
189.56190013885498
Epoch 1/4
Training…
Batch 500, Train Loss:0.0278,Train ACC: 99.0000
Batch 1000, Train Loss:0.0250,Train ACC: 99.0000
train Loss:0.0242 ACC:99.0000%
Validing…
valid Loss:0.0793 ACC:97.0000%
379.47217535972595
Epoch 2/4
Training…
Batch 500, Train Loss:0.0091,Train ACC: 99.0000
Batch 1000, Train Loss:0.0090,Train ACC: 99.0000
train Loss:0.0101 ACC:99.0000%
Validing…
valid Loss:0.0549 ACC:98.0000%
570.3123188018799
Epoch 3/4
Training…
Batch 500, Train Loss:0.0055,Train ACC: 99.0000
Batch 1000, Train Loss:0.0058,Train ACC: 99.0000
train Loss:0.0057 ACC:99.0000%
Validing…
valid Loss:0.0700 ACC:98.0000%
760.5475089550018
Epoch 4/4
Training…
Batch 500, Train Loss:0.0022,Train ACC: 99.0000
Batch 1000, Train Loss:0.0019,Train ACC: 99.0000
train Loss:0.0023 ACC:99.0000%
Validing…
valid Loss:0.0854 ACC:98.0000%
949.4390785694122