版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/xckkcxxck/article/details/82979049
在pytorch中去写训练函数和测试函数是一件重复的事，因此可以写成一个总的训练文件。
from datetime import datetime
import torch
import torch.nn.functional as F
from torch import nn
from torch.autograd import Variable
def get_acc(output, label):
total = output.shape[0]
_, pred_label = output.max(1)
num_correct = (pred_label == label).sum().item()
return num_correct / total
def train(net, train_data, valid_data, num_epochs, optimizer, criterion):
if torch.cuda.is_available():
net = net.cuda()
prev_time = datetime.now()
for epoch in range(num_epochs):
train_loss = 0
train_acc = 0
net = net.train()
for im, label in train_data:
if torch.cuda.is_available():
im = Variable(im.cuda()) # (bs, 3, h, w)
label = Variable(label.cuda()) # (bs, h, w)
else:
im = Variable(im)
label = Variable(label)
# forward
output = net(im)
loss = criterion(output, label)
# backward
optimizer.zero_grad()
loss.backward()
optimizer.step()
train_loss += loss.item()
train_acc += get_acc(output, label)
cur_time = datetime.now()
h, remainder = divmod((cur_time - prev_time).seconds, 3600)
m, s = divmod(remainder, 60)
time_str = "Time %02d:%02d:%02d" % (h, m, s)
if valid_data is not None:
valid_loss = 0
valid_acc = 0
net = net.eval()
for im, label in valid_data:
if torch.cuda.is_available():
im = Variable(im.cuda())
label = Variable(label.cuda())
else:
im = Variable(im)
label = Variable(label)
output = net(im)
loss = criterion(output, label)
valid_loss += loss.item()
valid_acc += get_acc(output, label)
epoch_str = (
"Epoch %d. Train Loss: %f, Train Acc: %f, Valid Loss: %f, Valid Acc: %f, "
% (epoch, train_loss / len(train_data),
train_acc / len(train_data), valid_loss / len(valid_data),
valid_acc / len(valid_data)))
else:
epoch_str = ("Epoch %d. Train Loss: %f, Train Acc: %f, " %
(epoch, train_loss / len(train_data),
train_acc / len(train_data)))
prev_time = cur_time
print(epoch_str + time_str)
def conv3x3(in_channel, out_channel, stride=1):
return nn.Conv2d(
in_channel, out_channel, 3, stride=stride, padding=1, bias=False)
class residual_block(nn.Module):
def __init__(self, in_channel, out_channel, same_shape=True):
super(residual_block, self).__init__()
self.same_shape = same_shape
stride = 1 if self.same_shape else 2
self.conv1 = conv3x3(in_channel, out_channel, stride=stride)
self.bn1 = nn.BatchNorm2d(out_channel)
self.conv2 = conv3x3(out_channel, out_channel)
self.bn2 = nn.BatchNorm2d(out_channel)
if not self.same_shape:
self.conv3 = nn.Conv2d(in_channel, out_channel, 1, stride=stride)
def forward(self, x):
out = self.conv1(x)
out = F.relu(self.bn1(out), True)
out = self.conv2(out)
out = F.relu(self.bn2(out), True)
if not self.same_shape:
x = self.conv3(x)
return F.relu(x + out, True)
class resnet(nn.Module):
def __init__(self, in_channel, num_classes, verbose=False):
super(resnet, self).__init__()
self.verbose = verbose
self.block1 = nn.Conv2d(in_channel, 64, 7, 2)
self.block2 = nn.Sequential(
nn.MaxPool2d(3, 2), residual_block(64, 64), residual_block(64, 64))
self.block3 = nn.Sequential(
residual_block(64, 128, False), residual_block(128, 128))
self.block4 = nn.Sequential(
residual_block(128, 256, False), residual_block(256, 256))
self.block5 = nn.Sequential(
residual_block(256, 512, False),
residual_block(512, 512), nn.AvgPool2d(3))
self.classifier = nn.Linear(512, num_classes)
def forward(self, x):
x = self.block1(x)
if self.verbose:
print('block 1 output: {}'.format(x.shape))
x = self.block2(x)
if self.verbose:
print('block 2 output: {}'.format(x.shape))
x = self.block3(x)
if self.verbose:
print('block 3 output: {}'.format(x.shape))
x = self.block4(x)
if self.verbose:
print('block 4 output: {}'.format(x.shape))
x = self.block5(x)
if self.verbose:
print('block 5 output: {}'.format(x.shape))
x = x.view(x.shape[0], -1)
x = self.classifier(x)
return x