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import torch
import torch.nn as nn
import torch.optim as optim
import torch.nn.functional as F
import os
import random
import argparse
from torchvision import transforms
from torch.autograd import Variable
import cv2
import numpy as np
class BaseLoader(torch.utils.data.Dataset):
def __init__(self, triplets, transform=None):
self.triplets = triplets
self.transform = transform
def __getitem__(self, index):
img1_pth, img2_pth, img3_pth = self.triplets[index]
img1 = cv2.imread(img1_pth)
img2 = cv2.imread(img2_pth)
img3 = cv2.imread(img3_pth)
try:
img1 = cv2.resize(img1, (args.picture_resize, args.picture_resize))
except Exception as e:
img1 = np.zeros((args.picture_resize, args.picture_resize, 3), dtype=np.uint8)
try:
img2 = cv2.resize(img2, (args.picture_resize, args.picture_resize))
except Exception as e:
img2 = np.zeros((args.picture_resize, args.picture_resize, 3), dtype=np.uint8)
try:
img3 = cv2.resize(img3, (args.picture_resize, args.picture_resize))
except Exception as e:
img3 = np.zeros((args.picture_resize, args.picture_resize, 3), dtype=np.uint8)
if self.transform is not None:
img1 = self.transform(img1)
img2 = self.transform(img2)
img3 = self.transform(img3)
return img1, img2, img3
def __len__(self):
return len(self.triplets)
class BaseCnn(nn.Module):
def __init__(self):
super(BaseCnn, self).__init__()
self.conv1 = nn.Sequential(
nn.Conv2d(3, 64, 3),
nn.MaxPool2d(2)
)
self.conv2 = nn.Sequential(
nn.Conv2d(64, 128, 3),
nn.MaxPool2d(2)
)
self.conv3 = nn.Sequential(
nn.Conv2d(128, 128, 3),
nn.MaxPool2d(2)
)
def forward(self, x):
x = self.conv1(x)
x = self.conv2(x)
x = self.conv3(x)
x = x.view(x.size(0), -1)
x = F.normalize(x, p=2, dim=1)
return x
class SiameseNet(nn.Module):
def __init__(self):
super(SiameseNet, self).__init__()
self.base = BaseCnn()
def forward(self, x1, x2, x3):
x1 = self.base(x1)
x2 = self.base(x2)
x3 = self.base(x3)
return x1, x2, x3
class BaseDset(object):
def __init__(self):
self.__base_path = ""
self.__train_set = {}
self.__test_set = {}
self.__train_keys = []
self.__test_keys = []
def load(self, base_path):
"""加载数据集,将类别和路径存储"""
self.__base_path = base_path
train_dir = os.path.join(self.__base_path, 'train')
test_dir = os.path.join(self.__base_path, 'test')
self.__train_set = {}
self.__test_set = {}
self.__train_keys = []
self.__test_keys = []
for class_id in os.listdir(train_dir):
# 对于train_dir里的每个文件夹名字 classi
class_dir = os.path.join(train_dir, class_id)
# 为其在训练集合中创建一个文件夹
# 在类别集合中,即train_keys中添加类别classi
self.__train_set[class_id] = []
self.__train_keys.append(class_id)
# 对于每个类别内的数据,将其路径添加到集合中
for img_name in os.listdir(class_dir):
img_path = os.path.join(class_dir, img_name)
self.__train_set[class_id].append(img_path)
# 同理对于测试集合也一样
for class_id in os.listdir(test_dir):
class_dir = os.path.join(test_dir, class_id)
self.__test_set[class_id] = []
self.__test_keys.append(class_id)
for img_name in os.listdir(class_dir):
img_path = os.path.join(class_dir, img_name)
self.__test_set[class_id].append(img_path)
return len(self.__train_keys), len(self.__test_keys)
# 获取三元组 !!!
def getTriplet(self, split='train'):
# 默认选取训练集
if split == 'train':
dataset = self.__train_set
keys = self.__train_keys
else:
dataset = self.__test_set
keys = self.__test_keys
# 随机指定两个正负类别,确保二者不一致
pos_idx = random.randint(0, len(keys) - 1)
while True:
neg_idx = random.randint(0, len(keys) - 1)
if pos_idx != neg_idx:
break
# 选定一个原始样本
pos_anchor_img_idx = random.randint(0, len(dataset[keys[pos_idx]]) - 1)
# 随机选择一个正样本,保证二者不一致
while True:
pos_img_idx = random.randint(0, len(dataset[keys[pos_idx]]) - 1)
if pos_anchor_img_idx != pos_img_idx:
break
# 随机选择一个负样本
neg_img_idx = random.randint(0, len(dataset[keys[neg_idx]]) - 1)
# 生成三元组
pos_anchor_img = dataset[keys[pos_idx]][pos_anchor_img_idx]
pos_img = dataset[keys[pos_idx]][pos_img_idx]
neg_img = dataset[keys[neg_idx]][neg_img_idx]
return pos_anchor_img, pos_img, neg_img
def train(data, model, criterion, optimizer, epoch):
print("******** Training ********")
total_loss = 0
model.train()
for batch_idx, img_triplet in enumerate(data):
# 提取数据
anchor_img, pos_img, neg_img = img_triplet
anchor_img, pos_img, neg_img = anchor_img.to(device), pos_img.to(device), neg_img.to(device)
anchor_img, pos_img, neg_img = Variable(anchor_img), Variable(pos_img), Variable(neg_img)
# 分别获得三个编码
E1, E2, E3 = model(anchor_img, pos_img, neg_img)
# 计算二者之间的欧式距离
dist_E1_E2 = F.pairwise_distance(E1, E2, 2)
dist_E1_E3 = F.pairwise_distance(E1, E3, 2)
target = torch.FloatTensor(dist_E1_E2.size()).fill_(-1)
target = target.to(device)
target = Variable(target)
# 大小如何?
loss = criterion(dist_E1_E2, dist_E1_E3, target)
total_loss += loss
optimizer.zero_grad()
loss.backward()
optimizer.step()
# 打印一波损失
log_step = args.train_log_step
if (batch_idx % log_step == 0) and (batch_idx != 0):
print('Train Epoch: {} [{}/{}] \t Loss: {:.4f}'.format(epoch, batch_idx, len(data), total_loss / log_step))
total_loss = 0
print("****************")
def test(data, model, criterion):
print("******** Testing ********")
with torch.no_grad():
model.eval()
accuracies = [0, 0, 0]
acc_threshes = [0, 0.2, 0.5]
total_loss = 0
for batch_idx, img_triplet in enumerate(data):
anchor_img, pos_img, neg_img = img_triplet
anchor_img, pos_img, neg_img = anchor_img.to(device), pos_img.to(device), neg_img.to(device)
anchor_img, pos_img, neg_img = Variable(anchor_img), Variable(pos_img), Variable(neg_img)
E1, E2, E3 = model(anchor_img, pos_img, neg_img)
dist_E1_E2 = F.pairwise_distance(E1, E2, 2)
dist_E1_E3 = F.pairwise_distance(E1, E3, 2)
target = torch.FloatTensor(dist_E1_E2.size()).fill_(-1)
target = target.to(device)
target = Variable(target)
loss = criterion(dist_E1_E2, dist_E1_E3, target)
total_loss += loss
for i in range(len(accuracies)):
prediction = (dist_E1_E3 - dist_E1_E2 - args.margin * acc_threshes[i]).cpu().data
prediction = prediction.view(prediction.numel())
prediction = (prediction > 0).float()
batch_acc = prediction.sum() * 1.0 / prediction.numel()
accuracies[i] += batch_acc
print('Test Loss: {}'.format(total_loss / len(data)))
for i in range(len(accuracies)):
# 0%等价于准确率其余是更严格的指标
print(
'Test Accuracy with diff = {}% of margin: {:.4f}'.format(acc_threshes[i] * 100,
accuracies[i] / len(data)))
print("****************")
return accuracies[-1]
def main():
# random_seed
torch.manual_seed(718)
torch.cuda.manual_seed(718)
data_path = r'./characters'
# data_path = r'./characters'
dset_obj = BaseDset()
dset_obj.load(data_path)
train_triplets = []
test_triplets = []
for i in range(args.num_train_samples):
pos_anchor_img, pos_img, neg_img = dset_obj.getTriplet()
train_triplets.append([pos_anchor_img, pos_img, neg_img])
for i in range(args.num_test_samples):
pos_anchor_img, pos_img, neg_img = dset_obj.getTriplet(split='test')
test_triplets.append([pos_anchor_img, pos_img, neg_img])
loader = BaseLoader
model = SiameseNet()
model.to(device)
criterion = torch.nn.MarginRankingLoss(margin=args.margin)
optimizer = optim.Adam(model.parameters(), lr=args.lr)
best_acc_of_50_margin = 0
best_epoch = 0
for epoch in range(1, args.epochs + 1):
# 初始化数据加载器
# 加载三元组
train_data_loader = torch.utils.data.DataLoader(
loader(train_triplets,
transform=transforms.Compose([
transforms.ToTensor(),
transforms.Normalize(0, 1)
])),
batch_size=args.batch_size, shuffle=True)
test_data_loader = torch.utils.data.DataLoader(
loader(test_triplets,
transform=transforms.Compose([
transforms.ToTensor(),
transforms.Normalize(0, 1)
])),
batch_size=args.batch_size, shuffle=True)
train(train_data_loader, model, criterion, optimizer, epoch)
acc_of_50_margin = test(test_data_loader, model, criterion)
model_to_save = {
"epoch": epoch + 1,
'state_dict': model.state_dict(),
}
if acc_of_50_margin > best_acc_of_50_margin:
best_acc_of_50_margin = acc_of_50_margin
best_epoch = epoch
if not args.disable_save_best_ckp:
result_path = os.path.join(args.result_dir)
file_name = os.path.join(args.result_dir, "best_checkpoint" + ".pt")
if not os.path.exists(result_path):
os.makedirs(result_path)
save_checkpoint(model_to_save, file_name)
if (epoch % args.ckp_freq == 0) and not args.disable_save_ckp:
result_path = os.path.join(args.result_dir)
file_name = os.path.join(args.result_dir, "checkpoint_" + str(epoch) + ".pt")
if not os.path.exists(result_path):
os.makedirs(result_path)
save_checkpoint(model_to_save, file_name)
print("Training is done.")
print(f"The best epoch of acc50, which is {best_acc_of_50_margin * 100}%, is {best_epoch}.")
def save_checkpoint(state, file_name):
torch.save(state, file_name)
if __name__ == '__main__':
# 超参数
parser = argparse.ArgumentParser(description='PyTorch Siamese Example')
parser.add_argument('--result_dir', default='output', type=str,
help='Directory to store results')
parser.add_argument('--epochs', type=int, default=10, metavar='N',
help='number of epochs to train (default: 10)')
parser.add_argument("--disable_save_ckp", default=False, action='store_true',
help="disable to save checkpoint frequently")
parser.add_argument('--ckp_freq', type=int, default=5, metavar='N',
help='Checkpoint Frequency (default: 1)')
parser.add_argument("--disable_save_best_ckp", default=False, action='store_true',
help="disable to save best checkpoint")
parser.add_argument('--train_log_step', type=int, default=500, metavar='M',
help='Number of iterations after which to log the loss')
parser.add_argument('--margin', type=float, default=1.0, metavar='M',
help='margin for triplet loss (default: 1.0)')
parser.add_argument('--batch_size', type=int, default=64, metavar='N',
help='input batch size for training (default: 64)')
parser.add_argument('--lr', type=float, default=0.0001, metavar='LR',
help='learning rate (default: 0.0001)')
parser.add_argument('--dataset', type=str, default='mnist', metavar='M',
help='Dataset (default: mnist)')
parser.add_argument('--picture_resize', type=int, default=200, metavar='M',
help='size of the picture to reset (default: 200)')
parser.add_argument('--num_train_samples', type=int, default=50000, metavar='M',
help='number of training samples (default: 50000)')
parser.add_argument('--num_test_samples', type=int, default=10000, metavar='M',
help='number of test samples (default: 10000)')
global args, device
device = 'cuda' if torch.cuda.is_available() else 'cpu'
args = parser.parse_args()
main()
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