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1.自建数据集与划分训练集与测试集
2.模型相关知识
3.model.py——定义AlexNet网络模型
4.train.py——加载数据集并训练，训练集计算损失值loss，测试集计算accuracy，保存训练好的网络参数
5.predict.py——利用训练好的网络参数后，用自己找的图像进行分类测试

一、自建数据集与划分训练集与测试集

1.自建数据文件夹

  首先我们确定这次分类种类，采用爬虫、官网数据集和自己拍照的照片获取三类，准备个文件夹，里面包含三个文件夹，文件夹名字随便取，最好是所属种类英文，每个文件夹照片数量最好一样多，五百多张以上。如我选了蒲公英，玫瑰，郁金香三类，如data_set包含flowers_data,它包含flowers_photos,它包含三个文件夹，分别是三个类文件夹。

2.划分训练集与测试集

这里需要使用通用的划分数据代码，这次是与flowers_data同一目录下运行。

import os
from shutil import copy
import randomdef mkfile(file):if not os.path.exists(file):os.makedirs(file)# 获取 photos 文件夹下除 .txt 文件以外所有文件夹名（即3种分类的类名）
file_path = 'flower_data/flower_photos'
flower_class = [cla for cla in os.listdir(file_path) if ".txt" not in cla]# 创建 训练集train 文件夹，并由3种类名在其目录下创建3个子目录
mkfile('flower_data/train')
for cla in flower_class:mkfile('flower_data/train/' + cla)# 创建 验证集val 文件夹，并由3种类名在其目录下创建3个子目录
mkfile('flower_data/val')
for cla in flower_class:mkfile('flower_data/val/' + cla)# 划分比例，训练集 : 验证集 = 9 : 1
split_rate = 0.1# 遍历3种花的全部图像并按比例分成训练集和验证集
for cla in flower_class:cla_path = file_path + '/' + cla + '/'  # 某一类别动作的子目录images = os.listdir(cla_path)  # iamges 列表存储了该目录下所有图像的名称num = len(images)eval_index = random.sample(images, k=int(num * split_rate))  # 从images列表中随机抽取 k 个图像名称for index, image in enumerate(images):# eval_index 中保存验证集val的图像名称if image in eval_index:image_path = cla_path + imagenew_path = 'flower_data/val/' + clacopy(image_path, new_path)  # 将选中的图像复制到新路径# 其余的图像保存在训练集train中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!")

最后运行，在flowers_data会多两个文件，是train和val（训练集和测试集）

二、模型相关知识

之前有文章介绍模型，如果不清楚可以点下链接转过去学习

深度学习卷积神经网络CNN之 VGGNet模型主vgg16和vgg19网络模型详解说明（理论篇）

三、model.py——定义AlexNet网络模型

这里还是直接复制给出原模型，不用改参数。

import torch.nn as nn
import torch# official pretrain weights
model_urls = {'vgg11': 'https://download.pytorch.org/models/vgg11-bbd30ac9.pth','vgg13': 'https://download.pytorch.org/models/vgg13-c768596a.pth','vgg16': 'https://download.pytorch.org/models/vgg16-397923af.pth','vgg19': 'https://download.pytorch.org/models/vgg19-dcbb9e9d.pth'
}class VGG(nn.Module):def __init__(self, features, num_classes=1000, init_weights=False):super(VGG, self).__init__()self.features = featuresself.classifier = nn.Sequential(nn.Linear(512*7*7, 4096),nn.ReLU(True),nn.Dropout(p=0.5),nn.Linear(4096, 4096),nn.ReLU(True),nn.Dropout(p=0.5),nn.Linear(4096, num_classes))if init_weights:self._initialize_weights()def forward(self, x):# N x 3 x 224 x 224x = self.features(x)# N x 512 x 7 x 7x = torch.flatten(x, start_dim=1)# N x 512*7*7x = 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')nn.init.xavier_uniform_(m.weight)if m.bias is not None:nn.init.constant_(m.bias, 0)elif isinstance(m, nn.Linear):nn.init.xavier_uniform_(m.weight)# nn.init.normal_(m.weight, 0, 0.01)nn.init.constant_(m.bias, 0)def make_features(cfg: list):layers = []in_channels = 3for v in cfg:if v == "M":layers += [nn.MaxPool2d(kernel_size=2, stride=2)]else:conv2d = nn.Conv2d(in_channels, v, kernel_size=3, padding=1)layers += [conv2d, nn.ReLU(True)]in_channels = vreturn nn.Sequential(*layers)cfgs = {'vgg11': [64, 'M', 128, 'M', 256, 256, 'M', 512, 512, 'M', 512, 512, 'M'],'vgg13': [64, 64, 'M', 128, 128, 'M', 256, 256, 'M', 512, 512, 'M', 512, 512, 'M'],'vgg16': [64, 64, 'M', 128, 128, 'M', 256, 256, 256, 'M', 512, 512, 512, 'M', 512, 512, 512, 'M'],'vgg19': [64, 64, 'M', 128, 128, 'M', 256, 256, 256, 256, 'M', 512, 512, 512, 512, 'M', 512, 512, 512, 512, 'M'],
}def vgg(model_name="vgg16", **kwargs):assert model_name in cfgs, "Warning: model number {} not in cfgs dict!".format(model_name)cfg = cfgs[model_name]model = VGG(make_features(cfg), **kwargs)return model

四、train.py——模型训练，加载数据集并训练，训练集计算损失值loss，测试集计算accuracy，保存训练好的网络参数

在63行修改为3，因为只有三类

net = vgg(model_name=model_name, num_classes=3, init_weights=True)

import os
import sys
import jsonimport torch
import torch.nn as nn
from torchvision import transforms, datasets
import torch.optim as optim
from tqdm import tqdmfrom model import vggdef main():device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")print("using {} device.".format(device))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)),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 pathimage_path = os.path.join(data_root, "data_set1", "flower_data1")  # flower data set pathassert os.path.exists(image_path), "{} path does not exist.".format(image_path)train_dataset = datasets.ImageFolder(root=os.path.join(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_idxcla_dict = dict((val, key) for key, val in flower_list.items())# write dict into json filejson_str = json.dumps(cla_dict, indent=4)with open('class_indices.json', 'w') as json_file:json_file.write(json_str)batch_size = 64nw = min([os.cpu_count(), batch_size if batch_size > 1 else 0, 8])  # number of workersprint('Using {} dataloader workers every process'.format(nw))train_loader = torch.utils.data.DataLoader(train_dataset,batch_size=batch_size, shuffle=True,num_workers=nw)validate_dataset = datasets.ImageFolder(root=os.path.join(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=False,num_workers=nw)print("using {} images for training, {} images for validation.".format(train_num,val_num))# test_data_iter = iter(validate_loader)# test_image, test_label = test_data_iter.next()model_name = "vgg16"net = vgg(model_name=model_name, num_classes=3, init_weights=True)%%%%%%%%这一行net.to(device)loss_function = nn.CrossEntropyLoss()optimizer = optim.Adam(net.parameters(), lr=0.0001)epochs = 10best_acc = 0.0save_path = './{}Net.pth'.format(model_name)train_steps = len(train_loader)for epoch in range(epochs):# trainnet.train()running_loss = 0.0train_bar = tqdm(train_loader, file=sys.stdout)for step, data in enumerate(train_bar):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()train_bar.desc = "train epoch[{}/{}] loss:{:.3f}".format(epoch + 1,epochs,loss)# validatenet.eval()acc = 0.0  # accumulate accurate number / epochwith torch.no_grad():val_bar = tqdm(validate_loader, file=sys.stdout)for val_data in val_bar:val_images, val_labels = val_dataoutputs = net(val_images.to(device))predict_y = torch.max(outputs, dim=1)[1]acc += torch.eq(predict_y, val_labels.to(device)).sum().item()val_accurate = acc / val_numprint('[epoch %d] train_loss: %.3f  val_accuracy: %.3f' %(epoch + 1, running_loss / train_steps, val_accurate))if val_accurate > best_acc:best_acc = val_accuratetorch.save(net.state_dict(), save_path)print('Finished Training')if __name__ == '__main__':main()

训练结果截图如下

五、predict.py——利用训练好的网络参数后，用自己找的图像进行分类测试

import os
import jsonimport torch
from PIL import Image
from torchvision import transforms
import matplotlib.pyplot as pltfrom model import vggdef main():device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")data_transform = transforms.Compose([transforms.Resize((224, 224)),transforms.ToTensor(),transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))])# load imageimg_path = "1.jpg"assert os.path.exists(img_path), "file: '{}' dose not exist.".format(img_path)img = Image.open(img_path)plt.imshow(img)# [N, C, H, W]img = data_transform(img)# expand batch dimensionimg = torch.unsqueeze(img, dim=0)# read class_indictjson_path = './class_indices.json'assert os.path.exists(json_path), "file: '{}' dose not exist.".format(json_path)with open(json_path, "r") as f:class_indict = json.load(f)# create modelmodel = vgg(model_name="vgg16", num_classes=5).to(device)# load model weightsweights_path = "./vgg16Net.pth"assert os.path.exists(weights_path), "file: '{}' dose not exist.".format(weights_path)model.load_state_dict(torch.load(weights_path))model.eval()with torch.no_grad():# predict classoutput = torch.squeeze(model(img.to(device))).cpu()predict = torch.softmax(output, dim=0)predict_cla = torch.argmax(predict).numpy()print_res = "class: {}   prob: {:.3}".format(class_indict[str(predict_cla)],predict[predict_cla].numpy())plt.title(print_res)for i in range(len(predict)):print("class: {:10}   prob: {:.3}".format(class_indict[str(i)],predict[i].numpy()))plt.show()if __name__ == '__main__':main()

在网上下载了一郁金香的图片，使用VGG16网络查看是否可以将图片种类正确识别。