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 | import timeimport copy
 import os
 import random
 import numpy as np
 import torch
 import torch.nn as nn
 import torch.optim as optim
 from torch.utils.data import DataLoader
 import torchvision.transforms as transforms
 from torchvision.models import alexnet
 from visdom import Visdom
 
 from utils.data.custom_classifier_dataset import CustomClassifierDataset
 from utils.data.custom_hard_negative_mining_dataset import CustomHardNegativeMiningDataset
 from utils.data.custom_batch_sampler import CustomBatchSampler
 from utils.util import check_dir
 from utils.util import save_model
 
 batch_positive = 32
 batch_negative = 96
 batch_total = 128
 
 
 def load_data(data_root_dir):
 transform = transforms.Compose([
 transforms.ToPILImage(),
 transforms.Resize((227, 227)),
 transforms.RandomHorizontalFlip(),
 transforms.ToTensor(),
 transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))
 ])
 
 data_loaders = {}
 data_sizes = {}
 remain_negative_list = list()
 for name in ['train', 'val']:
 data_dir = os.path.join(data_root_dir, name)
 
 data_set = CustomClassifierDataset(data_dir, transform=transform)
 if name is 'train':
 """
 使用hard negative mining方式
 初始正负样本比例为1:1。由于正样本数远小于负样本,所以以正样本数为基准,在负样本集中随机提取同样数目负样本作为初始负样本集
 """
 
 positive_list = data_set.get_positives()
 negative_list = data_set.get_negatives()
 init_negative_idxs = random.sample(range(len(negative_list)), len(positive_list))
 init_negative_list = [negative_list[idx] for idx in range(len(negative_list)) if idx in init_negative_idxs]
 remain_negative_list = [negative_list[idx] for idx in range(len(negative_list))
 if idx not in init_negative_idxs]
 
 data_set.set_negative_list(init_negative_list)
 data_loaders['remain'] = remain_negative_list
 
 sampler = CustomBatchSampler(data_set.get_positive_num(), data_set.get_negative_num(),
 batch_positive, batch_negative)
 
 
 data_loader = DataLoader(data_set, batch_size=batch_total, sampler=sampler, num_workers=8, drop_last=True)
 data_loaders[name] = data_loader
 data_sizes[name] = len(sampler)
 return data_loaders, data_sizes
 
 
 def hinge_loss(outputs, labels):
 """
 折页损失计算
 :param outputs: 大小为(N, num_classes)
 :param labels: 大小为(N)
 :return: 损失值
 """
 num_labels = len(labels)
 corrects = outputs[range(num_labels), labels].unsqueeze(0).T
 
 
 margin = 1.0
 margins = outputs - corrects + margin
 loss = torch.sum(torch.max(margins, 1)[0]) / len(labels)
 
 
 
 
 
 return loss
 
 
 def add_hard_negatives(hard_negative_list, negative_list, add_negative_list):
 for item in hard_negative_list:
 if len(add_negative_list) == 0:
 
 negative_list.append(item)
 add_negative_list.append(list(item['rect']))
 if list(item['rect']) not in add_negative_list:
 negative_list.append(item)
 add_negative_list.append(list(item['rect']))
 
 
 def get_hard_negatives(preds, cache_dicts):
 fp_mask = preds == 1
 tn_mask = preds == 0
 
 fp_rects = cache_dicts['rect'][fp_mask].numpy()
 fp_image_ids = cache_dicts['image_id'][fp_mask].numpy()
 
 tn_rects = cache_dicts['rect'][tn_mask].numpy()
 tn_image_ids = cache_dicts['image_id'][tn_mask].numpy()
 
 hard_negative_list = [{'rect': fp_rects[idx], 'image_id': fp_image_ids[idx]} for idx in range(len(fp_rects))]
 easy_negatie_list = [{'rect': tn_rects[idx], 'image_id': tn_image_ids[idx]} for idx in range(len(tn_rects))]
 
 return hard_negative_list, easy_negatie_list
 
 
 def train_model(data_loaders, model, criterion, optimizer, lr_scheduler, num_epochs=25, device=None):
 since = time.time()
 
 best_model_weights = copy.deepcopy(model.state_dict())
 best_acc = 0.0
 viz = Visdom(env='loss and val svm')
 viz.line(Y=np.column_stack((0., 0.)), X=np.column_stack((0., 0.)), win="{} loss/acc".format('train'),
 opts=dict(title='{} loss&acc'.format('train'), xlabel='epoch', ylabel='loss/acc',
 legend=["loss", "acc"]))
 viz.line(Y=np.column_stack((0., 0.)), X=np.column_stack((0., 0.)), win="{} loss/acc".format('val'),
 opts=dict(title='{} loss&acc'.format('val'), xlabel='epoch', ylabel='loss/acc',
 legend=["loss", "acc"]))
 
 
 for epoch in range(num_epochs):
 
 print('Epoch {}/{}'.format(epoch, num_epochs ))
 print('-' * 10)
 
 
 for phase in ['train', 'val']:
 
 
 
 if phase == 'train':
 model.train()
 else:
 model.eval()
 
 running_loss = 0.0
 running_corrects = 0
 batch_i = 0
 
 
 data_set = data_loaders[phase].dataset
 print('{} - positive_num: {} - negative_num: {} - data size: {}'.format(
 phase, data_set.get_positive_num(), data_set.get_negative_num(), data_sizes[phase]))
 
 
 for inputs, labels, cache_dicts in data_loaders[phase]:
 inputs = inputs.to(device)
 labels = labels.to(device)
 
 
 optimizer.zero_grad()
 
 
 
 with torch.set_grad_enabled(phase == 'train'):
 outputs = model(inputs)
 
 _, preds = torch.max(outputs, 1)
 loss = criterion(outputs, labels)
 
 
 if phase == 'train':
 loss.backward()
 optimizer.step()
 
 
 running_loss += loss.item() * inputs.size(0)
 running_corrects += torch.sum(preds == labels.data)
 batch_i += 1
 print("batch", batch_i, "running_loss_adds=", running_loss)
 
 if phase == 'train':
 lr_scheduler.step()
 
 epoch_loss = running_loss / data_sizes[phase]
 epoch_acc = running_corrects.double() / data_sizes[phase]
 
 print('{} Loss: {:.4f} Acc: {:.4f}'.format(
 phase, epoch_loss, epoch_acc))
 
 viz.line(Y=np.column_stack(([epoch_loss], [epoch_acc])), X=np.column_stack(([epoch + 1], [epoch + 1])),
 win="{} loss/acc".format(phase),
 opts=dict(title='{} loss&acc'.format(phase), xlabel='epoch', ylabel='loss/acc',
 legend=["loss", "acc"]), update="append")
 
 
 if phase == 'val' and epoch_acc > best_acc:
 best_acc = epoch_acc
 best_model_weights = copy.deepcopy(model.state_dict())
 
 
 train_dataset = data_loaders['train'].dataset
 remain_negative_list = data_loaders['remain']
 jpeg_images = train_dataset.get_jpeg_images()
 transform = train_dataset.get_transform()
 
 with torch.set_grad_enabled(False):
 remain_dataset = CustomHardNegativeMiningDataset(remain_negative_list, jpeg_images, transform=transform)
 remain_data_loader = DataLoader(remain_dataset, batch_size=batch_total, num_workers=8, drop_last=True)
 
 
 negative_list = train_dataset.get_negatives()
 
 add_negative_list = data_loaders.get('add_negative', [])
 
 running_corrects = 0
 
 for inputs, labels, cache_dicts in remain_data_loader:
 inputs = inputs.to(device)
 labels = labels.to(device)
 
 
 optimizer.zero_grad()
 
 outputs = model(inputs)
 
 _, preds = torch.max(outputs, 1)
 
 running_corrects += torch.sum(preds == labels.data)
 
 hard_negative_list, easy_neagtive_list = get_hard_negatives(preds.cpu().numpy(), cache_dicts)
 add_hard_negatives(hard_negative_list, negative_list, add_negative_list)
 
 remain_acc = running_corrects.double() / len(remain_negative_list)
 print('remiam negative size: {}, acc: {:.4f}'.format(len(remain_negative_list), remain_acc))
 
 
 train_dataset.set_negative_list(negative_list)
 tmp_sampler = CustomBatchSampler(train_dataset.get_positive_num(), train_dataset.get_negative_num(),
 batch_positive, batch_negative)
 data_loaders['train'] = DataLoader(train_dataset, batch_size=batch_total, sampler=tmp_sampler,
 num_workers=8, drop_last=True)
 data_loaders['add_negative'] = add_negative_list
 
 
 data_sizes['train'] = len(tmp_sampler)
 
 
 save_model(model, 'models/linear_svm_alexnet_car_%d.pth' % epoch)
 
 time_elapsed = time.time() - since
 print('Training complete in {:.0f}m {:.0f}s'.format(
 time_elapsed // 60, time_elapsed % 60))
 print('Best val Acc: {:4f}'.format(best_acc))
 
 
 model.load_state_dict(best_model_weights)
 return model
 
 
 if __name__ == '__main__':
 device = torch.device('cuda:0' if torch.cuda.is_available() else 'cpu')
 
 data_loaders, data_sizes = load_data('./data/classifier_car')
 
 model_path = './models/alexnet_car.pth'
 model = alexnet()
 num_classes = 2
 num_features = model.classifier[6].in_features
 model.classifier[6] = nn.Linear(num_features, num_classes)
 model.load_state_dict(torch.load(model_path))
 model.eval()
 
 for param in model.parameters():
 param.requires_grad = False
 
 model.classifier[6] = nn.Linear(num_features, num_classes)
 
 model = model.to(device)
 criterion = hinge_loss
 
 optimizer = optim.SGD(model.parameters(), lr=1e-4, momentum=0.9)
 
 lr_schduler = optim.lr_scheduler.StepLR(optimizer, step_size=4, gamma=0.1)
 best_model = train_model(data_loaders, model, criterion, optimizer, lr_schduler, num_epochs=25, device=device)
 
 save_model(best_model, 'models/best_linear_svm_alexnet_car.pth')
 print('done')
 
 |