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2021-07(1)

2021-08(8)

利用pytorch 训练常见分类网络

发布于2019-08-07 14:51     阅读(1368)     评论(0)     点赞(1)     收藏(1)



自己数据集制作

这里以kaggle比赛猫狗两类数据集为例,

cat-dog

首先根据数据集制作一个txt的路径文档,代码如下

import os
from PIL import Image
path='E:\dataset\kaggle_cat_dog\PetImages/'
filetrain=open("train.txt",'w')
filetest=open("test.txt",'w')

num=0
for class_pet in os.listdir(path):
    for img in os.listdir(os.path.join(path,class_pet)):
         _, ext = os.path.splitext(img)
         
         absolute_path=os.path.join(path,class_pet,img)
         if ext=='jpg'or 'png'and num%8!=0:
             filetrain.writelines(absolute_path+" 0"+'\n') if class_pet=='Cat' else filetrain.writelines(absolute_path+" 1"+"\n")
         elif ext=='jpg' or 'png' and num%8==0:
             filetest.writelines(absolute_path + " 0" + '\n') if class_pet == 'Cat' else filetest.writelines(
                 absolute_path + " 1" + "\n")
         num+=1
filetrain.close()
filetest.close()

其中通过num%8将数据集按照8:1分成了训练集与测试集。最终得到了两个txt文件夹。

然后将数据集加载并读取,代码为

import torch
import torchvision
import torchvision.transforms as transforms
from PIL import Image
from torch.utils.data import DataLoader,Dataset
class MyDataset(Dataset):
    def __init__(self,root,datatxt,transform=None):
        super(MyDataset,self).__init__()
        fh=open(root+datatxt,'r')
        imgs=[]
        for line in fh:
            line=line.rstrip()
            words=line.split()
            imgs.append((words[0],int(words[1])))
        self.imgs=imgs
        self.transform=transform
    def __getitem__(self,index):
        fn,label=self.imgs[index]
        img=Image.open(fn).convert('RGB')
        if self.transform is not None:
            img=self.transform(img)
        return img,label
    def __len__(self):
        return len(self.imgs)
transform_train = transforms.Compose([
            transforms.RandomCrop(224),
            transforms.RandomHorizontalFlip(),
            transforms.ToTensor(),
            ])

transform_test = transforms.Compose([
    transforms.ToTensor(),
])

trainset=MyDataset(root='E:/tensorflow\SENet-Tensorflow-master/',datatxt='train.txt',transform=transform_train)
trainloader=DataLoader(trainset,batch_size=8,shuffle=True)
testset=MyDataset(root='E:/tensorflow\SENet-Tensorflow-master/',datatxt='test.txt',transform=transform_test)
testloader=DataLoader(testset,batch_size=8,shuffle=True)

接下来是添加网络模型,以vgg16为例

import torch
import torch.nn as tnn
import torchvision.datasets as dsets
import torchvision.transforms as transforms
from torch.autograd import Variable
class VGG16(tnn.Module):
    def __init__(self):
        super(VGG16, self).__init__()
        self.layer1 = tnn.Sequential(

            # 1-1 conv layer
            tnn.Conv3d(3, 64, kernel_size=3, padding=1),
            tnn.BatchNorm3d(64),
            tnn.ReLU(),

            # 1-2 conv layer
            tnn.Conv3d(64, 64, kernel_size=3, padding=1),
            tnn.BatchNorm3d(64),
            tnn.ReLU(),

            # 1 Pooling layer
            tnn.MaxPool3d(kernel_size=2, stride=2))

        self.layer2 = tnn.Sequential(

            # 2-1 conv layer
            tnn.Conv3d(64, 128, kernel_size=3, padding=1),
            tnn.BatchNorm3d(128),
            tnn.ReLU(),

            # 2-2 conv layer
            tnn.Conv3d(128, 128, kernel_size=3, padding=1),
            tnn.BatchNorm3d(128),
            tnn.ReLU(),

            # 2 Pooling lyaer
            tnn.MaxPool3d(kernel_size=2, stride=2))

        self.layer3 = tnn.Sequential(

            # 3-1 conv layer
            tnn.Conv3d(128, 256, kernel_size=3, padding=1),
            tnn.BatchNorm3d(256),
            tnn.ReLU(),

            # 3-2 conv layer
            tnn.Conv3d(256, 256, kernel_size=3, padding=1),
            tnn.BatchNorm3d(256),
            tnn.ReLU(),

            # 3 Pooling layer
            tnn.MaxPool3d(kernel_size=2, stride=2))

        self.layer4 = tnn.Sequential(

            # 4-1 conv layer
            tnn.Conv3d(256, 512, kernel_size=3, padding=1),
            tnn.BatchNorm3d(512),
            tnn.ReLU(),

            # 4-2 conv layer
            tnn.Conv3d(512, 512, kernel_size=3, padding=1),
            tnn.BatchNorm3d(512),
            tnn.ReLU(),

            # 4 Pooling layer
            tnn.MaxPool3d(kernel_size=2, stride=2))

        self.layer5 = tnn.Sequential(

            # 5-1 conv layer
            tnn.Conv3d(512, 512, kernel_size=3, padding=1),
            tnn.BatchNorm3d(512),
            tnn.ReLU(),

            # 5-2 conv layer
            tnn.Conv3d(512, 512, kernel_size=3, padding=1),
            tnn.BatchNorm3d(512),
            tnn.ReLU(),

            # 5 Pooling layer
            tnn.MaxPool3d(kernel_size=2, stride=2))

        self.layer6 = tnn.Sequential(

            # 6 Fully connected layer
            # Dropout layer omitted since batch normalization is used.
            tnn.Linear(4096, 4096),
            tnn.BatchNorm1d(4096),
            tnn.ReLU())

        self.layer7 = tnn.Sequential(

            # 7 Fully connected layer
            # Dropout layer omitted since batch normalization is used.
            tnn.Linear(4096, 4096),
            tnn.BatchNorm1d(4096),
            tnn.ReLU())

        self.layer8 = tnn.Sequential(

            # 8 output layer
            tnn.Linear(4096, 2),
            tnn.BatchNorm1d(2),
            tnn.Softmax())

        def forward(self, x):
            out = self.layer1(x)
            out = self.layer2(out)
            out = self.layer3(out)
            out = self.layer4(out)
            out = self.layer5(out)
            vgg16_features = out.view(out.size(0), -1)
            out = self.layer6(vgg16_features)
            out = self.layer7(out)
            out = self.layer8(out)

            return vgg16_features, out

模型定义结束后,开始训练:

import time
import torch.nn as nn
import torch.nn.parallel
import torch.backends.cudnn as cudnn
import torch.optim
import torch.utils.data
class AverageMeter(object):
    """Computes and stores the average and current value"""
    def __init__(self):
        self.reset()

    def reset(self):
        self.val = 0
        self.avg = 0
        self.sum = 0
        self.count = 0

    def update(self, val, n=1):
        self.val = val
        self.sum += val * n
        self.count += n
        self.avg = self.sum / self.count
def accuracy(output, target, topk=(1,)):
    """Computes the precision@k for the specified values of k"""
    maxk = max(topk)
    batch_size = target.size(0)

    _, pred = output.topk(maxk, 1, True, True)
    pred = pred.t()
    correct = pred.eq(target.view(1, -1).expand_as(pred))

    res = []
    for k in topk:
        correct_k = correct[:k].view(-1).float().sum(0)
        res.append(correct_k.mul_(100.0 / batch_size))
    return res
def train(train_loader, model, criterion, optimizer, epoch):
    
    batch_time = AverageMeter()
    losses = AverageMeter()
    top1 = AverageMeter()

    # switch to train mode
    model.train()

    end = time.time()
    for i, (input, target) in enumerate(trainloader):

        target = target.cuda(async=True)
        input = input.cuda()
        input_var = torch.autograd.Variable(input)
        target_var = torch.autograd.Variable(target)

        # compute output
        output = model(input_var)
        loss = criterion(output, target_var)

        # measure accuracy and record loss
        prec1 = accuracy(output.data, target, topk=(1,))[0]
        losses.update(loss.data[0], input.size(0))
        top1.update(prec1[0], input.size(0))

        # compute gradient and do SGD step
        optimizer.zero_grad()
        loss.backward()
        optimizer.step()

        # measure elapsed time
        batch_time.update(time.time() - end)
        end = time.time()

        if i % args.print_freq == 0:
            print('Epoch: [{0}][{1}/{2}]\t'
                  'Time {batch_time.val:.3f} ({batch_time.avg:.3f})\t'
                  'Loss {loss.val:.4f} ({loss.avg:.4f})\t'
                  'Prec@1 {top1.val:.3f} ({top1.avg:.3f})'.format(
                      epoch, i, len(train_loader), batch_time=batch_time,
                      loss=losses, top1=top1))

测试函数为

def validate(val_loader, model, criterion, epoch):
    """Perform validation on the validation set"""
    batch_time = AverageMeter()
    losses = AverageMeter()
    top1 = AverageMeter()

    # switch to evaluate mode
    model.eval()

    end = time.time()
    for i, (input, target) in enumerate(testloader):
        target = target.cuda(async=True)
        input = input.cuda()
        input_var = torch.autograd.Variable(input, volatile=True)
        target_var = torch.autograd.Variable(target, volatile=True)

        # compute output
        output = model(input_var)
        loss = criterion(output, target_var)

        # measure accuracy and record loss
        prec1 = accuracy(output.data, target, topk=(1,))[0]
        losses.update(loss.data[0], input.size(0))
        top1.update(prec1[0], input.size(0))

        # measure elapsed time
        batch_time.update(time.time() - end)
        end = time.time()

        if i % args.print_freq == 0:
            print('Test: [{0}/{1}]\t'
                  'Time {batch_time.val:.3f} ({batch_time.avg:.3f})\t'
                  'Loss {loss.val:.4f} ({loss.avg:.4f})\t'
                  'Prec@1 {top1.val:.3f} ({top1.avg:.3f})'.format(
                      i, len(val_loader), batch_time=batch_time, loss=losses,
                      top1=top1))

    print(' * Prec@1 {top1.avg:.3f}'.format(top1=top1))
    # log to TensorBoard
    #if args.tensorboard:
     #  log_value('val_loss', losses.avg, epoch)
      #  log_value('val_acc', top1.avg, epoch)
    return top1.avg
def accuracy(output, target, topk=(1,)):
    """Computes the precision@k for the specified values of k"""
    maxk = max(topk)
    batch_size = target.size(0)

    _, pred = output.topk(maxk, 1, True, True)
    pred = pred.t()
    correct = pred.eq(target.view(1, -1).expand_as(pred))

    res = []
    for k in topk:
        correct_k = correct[:k].view(-1).float().sum(0)
        res.append(correct_k.mul_(100.0 / batch_size))
    return res

最后添加主函数:

model = VGG16()

model = model.cuda()

criterion = nn.CrossEntropyLoss().cuda()
optimizer = torch.optim.SGD(model.parameters(), 0.001,
                                momentum=0.9,
                                nesterov=True,
                                weight_decay=1*e-4)

for epoch in range(0, 200):
        adjust_learning_rate(optimizer, epoch)

        # train for one epoch
        train(trainloader, model, criterion, optimizer, epoch)

        # evaluate on validation set
        prec1 = validate(testloader, model, criterion, epoch)

        best_prec1=0
        is_best = prec1 > best_prec1
        best_prec1 = max(prec1, best_prec1)
       
print('Best accuracy: ', best_prec1)

代码中的文件路径按照自己文件夹做相应修改。







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作者:dkjf787

链接:https://www.pythonheidong.com/blog/article/11397/9ff13f1bc7228fcecf5e/

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