目录
论文：
torch实现：
数据集分割处理脚本spile_data.py
定义一个AlexNet网络model.py
训练脚本train.py
预测脚本predict.py
论文：
ImageNet Classification with Deep Convolutional Neural Networks
https://papers.nips.cc/paper/2012/file/c399862d3b9d6b76c8436e924a68c45b-Paper.pdf
torch实现：
本文测试场景为花的分类，数据集下载地址：
http://download.tensorflow.org/example_images/flower_photos.tgz数据集分割处理脚本spile_data.py
import os
from shutil import copy
import randomdef mkfile(file):if not os.path.exists(file):os.makedirs(file)file = 'flower_data/flower_photos'
flower_class = [cla for cla in os.listdir(file) if ".txt" not in cla]
mkfile('flower_data/train')
for cla in flower_class:mkfile('flower_data/train/'+cla)mkfile('flower_data/val')
for cla in flower_class:mkfile('flower_data/val/'+cla)split_rate = 0.1
for cla in flower_class:cla_path = file + '/' + cla + '/'images = os.listdir(cla_path)num = len(images)eval_index = random.sample(images, k=int(num*split_rate))for index, image in enumerate(images):if image in eval_index:image_path = cla_path + imagenew_path = 'flower_data/val/' + clacopy(image_path, new_path)else:image_path = cla_path + imagenew_path = 'flower_data/train/' + clacopy(image_path, new_path)print("\r[{}] processing [{}/{}]".format(cla, index+1, num), end="") # processing barprint()print("processing done!") 
定义一个AlexNet网络model.py
import torch.nn as nn
import torchclass AlexNet(nn.Module):def __init__(self, num_classes=1000, init_weights=False):super(AlexNet, self).__init__()self.features = nn.Sequential( #打包nn.Conv2d(3, 48, kernel_size=11, stride=4, padding=2), # input[3, 224, 224] output[48, 55, 55] 自动舍去小数点后nn.ReLU(inplace=True), #inplace 可以载入更大模型nn.MaxPool2d(kernel_size=3, stride=2), # output[48, 27, 27] kernel_num为原论文一半nn.Conv2d(48, 128, kernel_size=5, padding=2), # output[128, 27, 27]nn.ReLU(inplace=True),nn.MaxPool2d(kernel_size=3, stride=2), # output[128, 13, 13]nn.Conv2d(128, 192, kernel_size=3, padding=1), # output[192, 13, 13]nn.ReLU(inplace=True),nn.Conv2d(192, 192, kernel_size=3, padding=1), # output[192, 13, 13]nn.ReLU(inplace=True),nn.Conv2d(192, 128, kernel_size=3, padding=1), # output[128, 13, 13]nn.ReLU(inplace=True),nn.MaxPool2d(kernel_size=3, stride=2), # output[128, 6, 6])self.classifier = nn.Sequential(nn.Dropout(p=0.5),#全链接nn.Linear(128 * 6 * 6, 2048),nn.ReLU(inplace=True),nn.Dropout(p=0.5),nn.Linear(2048, 2048),nn.ReLU(inplace=True),nn.Linear(2048, num_classes),)if init_weights:self._initialize_weights()def forward(self, x):x = self.features(x)x = torch.flatten(x, start_dim=1) #展平 或者view()x = self.classifier(x)return xdef _initialize_weights(self):for m in self.modules():if isinstance(m, nn.Conv2d):nn.init.kaiming_normal_(m.weight, mode='fan_out', nonlinearity='relu') #何教授方法if m.bias is not None:nn.init.constant_(m.bias, 0)elif isinstance(m, nn.Linear):nn.init.normal_(m.weight, 0, 0.01) #正态分布赋值nn.init.constant_(m.bias, 0)训练脚本train.py
import torch
import torch.nn as nn
from torchvision import transforms, datasets, utils
import matplotlib.pyplot as plt
import numpy as np
import torch.optim as optim
from model import AlexNet
import os
import json
import time#device : GPU or CPU
device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
print(device)#数据转换
data_transform = {"train": transforms.Compose([transforms.RandomResizedCrop(224),transforms.RandomHorizontalFlip(),transforms.ToTensor(),transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))]),"val": transforms.Compose([transforms.Resize((224, 224)), # cannot 224, must (224, 224)transforms.ToTensor(),transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))])}#data_root = os.path.abspath(os.path.join(os.getcwd(), "../..")) # get data root path
data_root = os.getcwd()
image_path = data_root + "/flower_data/" # flower data set path
train_dataset = datasets.ImageFolder(root=image_path + "/train",transform=data_transform["train"])
train_num = len(train_dataset)# {'daisy':0, 'dandelion':1, 'roses':2, 'sunflower':3, 'tulips':4}
flower_list = train_dataset.class_to_idx
cla_dict = dict((val, key) for key, val in flower_list.items())
# write dict into json file
json_str = json.dumps(cla_dict, indent=4)
with open('class_indices.json', 'w') as json_file:json_file.write(json_str)batch_size = 32
train_loader = torch.utils.data.DataLoader(train_dataset,batch_size=batch_size, shuffle=True,num_workers=0)validate_dataset = datasets.ImageFolder(root=image_path + "/val",transform=data_transform["val"])
val_num = len(validate_dataset)
validate_loader = torch.utils.data.DataLoader(validate_dataset,batch_size=batch_size, shuffle=True,num_workers=0)test_data_iter = iter(validate_loader)
test_image, test_label = test_data_iter.next()
#print(test_image[0].size(),type(test_image[0]))
#print(test_label[0],test_label[0].item(),type(test_label[0]))#显示图像，之前需把validate_loader中batch_size改为4
# def imshow(img):
# img = img / 2 + 0.5 # unnormalize
# npimg = img.numpy()
# plt.imshow(np.transpose(npimg, (1, 2, 0)))
# plt.show()
#
# print(' '.join('%5s' % cla_dict[test_label[j].item()] for j in range(4)))
# imshow(utils.make_grid(test_image))net = AlexNet(num_classes=5, init_weights=True)net.to(device)
#损失函数:这里用交叉熵
loss_function = nn.CrossEntropyLoss()
#优化器 这里用Adam
optimizer = optim.Adam(net.parameters(), lr=0.0002)
#训练参数保存路径
save_path = './AlexNet.pth'
#训练过程中最高准确率
best_acc = 0.0#开始进行训练和测试，训练一轮，测试一轮
for epoch in range(10):# trainnet.train() #训练过程中，使用之前定义网络中的dropoutrunning_loss = 0.0t1 = time.perf_counter()total = 0correct = 0.0for step, data in enumerate(train_loader, start=0):images, labels = dataoptimizer.zero_grad()outputs = net(images.to(device))loss = loss_function(outputs, labels.to(device))loss.backward()optimizer.step()# print statisticsrunning_loss += loss.item()# print train processrate = (step + 1) / len(train_loader)a = "*" * int(rate * 50)b = "." * int((1 - rate) * 50)print("\rtrain loss: {:^3.0f}%[{}->{}]{:.3f}".format(int(rate * 100), a, b, loss), end="")print()print(time.perf_counter()-t1)# validatenet.eval() #测试过程中不需要dropout，使用所有的神经元acc = 0.0 # accumulate accurate number / epochwith torch.no_grad():for val_data in validate_loader:val_images, val_labels = val_dataoutputs = net(val_images.to(device))predict_y = torch.max(outputs, dim=1)[1]acc += (predict_y == val_labels.to(device)).sum().item()val_accurate = acc / val_numif val_accurate > best_acc:best_acc = val_accuratetorch.save(net.state_dict(), save_path)print('[epoch %d] train_loss: %.3f test_accuracy: %.3f' %(epoch + 1, running_loss / step, val_accurate))print('Finished Training')预测脚本predict.py
import torch
from model import AlexNet
from PIL import Image
from torchvision import transforms
import matplotlib.pyplot as plt
import jsondata_transform = transforms.Compose([transforms.Resize((224, 224)),transforms.ToTensor(),transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))])# load image
img = Image.open("./2.jpg").convert('RGB') #验证太阳花
#img = Image.open("./roses.jpg") #验证玫瑰花
plt.imshow(img)
# [N, C, H, W]
img = data_transform(img)
# expand batch dimension
img = torch.unsqueeze(img, dim=0)# read class_indict
try:json_file = open('./class_indices.json', 'r')class_indict = json.load(json_file)
except Exception as e:print(e)exit(-1)# create model
model = AlexNet(num_classes=5)
# load model weights
model_weight_path = "./AlexNet.pth"
model.load_state_dict(torch.load(model_weight_path))
model.eval()
with torch.no_grad():# predict classoutput = torch.squeeze(model(img))predict = torch.softmax(output, dim=0)predict_cla = torch.argmax(predict).numpy()
print(class_indict[str(predict_cla)], predict[predict_cla].item())
plt.show()