ResNet代码实现

开发环境

• python–3.7
• torch–1.8+cu101
• torchsummary
• torchvision–0.6.1+cu101
• PIL
• numpy
• opencv-python
• pillow
• imageio

准备工作

ResNet预训练模型下载地址：
https://download.pytorch.org/models/resnet18-5c106cde.pth
cifar10数据集下载地址：
https://www.cs.toronto.edu/~kriz/cifar.html

项目代码结构

• data文件夹下存储了cifar10数据集（python版）和resnet18预训练权重
• src存储了resnet推理demo程序和resnet训练程序
• tools存储了通用程序文件：cifar10转png程序、cifar10数据集构建文件、resnet18/50模型构建程序、模型训练程序

cifar10数据集转换（解析）程序

import numpy as np
import os
import sys
import pickle
import imageio

BASE_DIR = os.path.dirname(os.path.abspath(__file__))


def unpickle(file):
    fo = open(file, 'rb')

    if sys.version_info < (3, 0):
        dict_ = pickle.load(fo)
    else:
        dict_ = pickle.load(fo, encoding='bytes')
    fo.close()
    return dict_


def my_mkdir(my_dir):
    if not os.path.isdir(my_dir):
        os.makedirs(my_dir)


if __name__ == '__main__':

    data_dir = os.path.join(BASE_DIR, "..", "data", "cifar-10-batches-py")
    train_o_dir = os.path.join(BASE_DIR, "..", "data", "cifar10_train")
    test_o_dir = os.path.join(BASE_DIR, "..",  "data", "cifar10_test")

    for j in range(1, 6):
        data_path = os.path.join(data_dir,  "data_batch_" + str(j))  # data_batch_12345
        train_data = unpickle(data_path)
        print(data_path + " is loading...")

        for i in range(0, 10000):
            img = np.reshape(train_data[b'data'][i], (3, 32, 32))
            img = img.transpose(1, 2, 0)

            label_num = str(train_data[b'labels'][i])
            o_dir = os.path.join(train_o_dir, label_num)
            my_mkdir(o_dir)

            img_name = label_num + '_' + str(i + (j - 1)*10000) + '.png'
            img_path = os.path.join(o_dir, img_name)
            imageio.imwrite(img_path, img)
        print(data_path + " loaded.")

    print("test_batch is loading...")

    test_data_path = os.path.join(data_dir, "test_batch")
    test_data = unpickle(test_data_path)
    for i in range(0, 10000):
        img = np.reshape(test_data[b'data'][i], (3, 32, 32))
        img = img.transpose(1, 2, 0)

        label_num = str(test_data[b'labels'][i])
        o_dir = os.path.join(test_o_dir, label_num)
        my_mkdir(o_dir)

        img_name = label_num + '_' + str(i) + '.png'
        img_path = os.path.join(o_dir, img_name)
        imageio.imwrite(img_path, img)

    print("test_batch loaded.")

cifar10数据集构建程序

import os
from PIL import Image
from torch.utils.data import Dataset


class CifarDataset(Dataset):
    def __init__(self, data_dir, transform=None):
        assert (os.path.exists(data_dir)), "data_dir:{} 不存在".format(data_dir)

        self.data_dir = data_dir
        self._get_img_info()
        self.transform = transform

    def __getitem__(self, index):
        fn, label = self.img_info[index]
        img = Image.open(fn).convert('RGB')

        if self.transform is not None:
            img = self.transform(img)

        return img, label

    def __len__(self):
        if len(self.img_info) == 0:
            raise Exception("未获取任何图片路径，请检查dataset及文件路径！")
        return len(self.img_info)

    def _get_img_info(self):
        sub_dir_ = [name for name in os.listdir(self.data_dir) if os.path.isdir(os.path.join(self.data_dir, name))]
        sub_dir = [os.path.join(self.data_dir, c) for c in sub_dir_]

        self.img_info = []
        for c_dir in sub_dir:
            path_img = [(os.path.join(c_dir, i), int(os.path.basename(c_dir))) for i in os.listdir(c_dir) if
                        i.endswith("png")]
            self.img_info.extend(path_img)

ResNet模型获取程序

import torch
import torchvision.models as models


def get_resnet_18(path_state_dict, device, vis_model=False):
    """
    创建模型，加载参数
    :param path_state_dict:
    :return:
    """
    model = models.resnet18()
    if path_state_dict:
        pretrained_state_dict = torch.load(path_state_dict)
        model.load_state_dict(pretrained_state_dict)
    model.eval()

    if vis_model:
        from torchsummary import summary
        summary(model, input_size=(3, 224, 224), device="cpu")

    model.to(device)
    return model


def get_resnet_50(path_state_dict, device, vis_model=False):
    """
    创建模型，加载参数
    :param path_state_dict:
    :return:
    """
    model = models.resnet50()
    if path_state_dict:
        pretrained_state_dict = torch.load(path_state_dict)
        model.load_state_dict(pretrained_state_dict)
    model.eval()

    if vis_model:
        from torchsummary import summary
        summary(model, input_size=(3, 224, 224), device="cpu")

    model.to(device)
    return model

resnet推理demo程序

import os
os.environ['NLS_LANG'] = 'SIMPLIFIED CHINESE_CHINA.UTF8'
import time
import json
import torch
import torchvision.transforms as transforms
from PIL import Image
from matplotlib import pyplot as plt
from tools.common_tools import get_resnet_18, get_resnet_50
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")


def img_transform(img_rgb, transform=None):
    """
    将数据转换为模型读取的形式
    :param img_rgb: PIL Image
    :param transform: torchvision.transform
    :return: tensor
    """

    if transform is None:
        raise ValueError("找不到transform！必须有transform对img进行处理")

    img_t = transform(img_rgb)
    return img_t


def process_img(path_img):

    # hard code
    norm_mean = [0.485, 0.456, 0.406]
    norm_std = [0.229, 0.224, 0.225]
    inference_transform = transforms.Compose([
        transforms.Resize(256),
        transforms.CenterCrop((224, 224)),
        transforms.ToTensor(),
        transforms.Normalize(norm_mean, norm_std),
    ])

    # path --> img
    img_rgb = Image.open(path_img).convert('RGB')

    # img --> tensor
    img_tensor = img_transform(img_rgb, inference_transform)
    img_tensor.unsqueeze_(0)        # chw --> bchw
    img_tensor = img_tensor.to(device)

    return img_tensor, img_rgb


def load_class_names(p_clsnames, p_clsnames_cn):
    """
    加载标签名
    :param p_clsnames:
    :param p_clsnames_cn:
    :return:
    """
    with open(p_clsnames, "r") as f:
        class_names = json.load(f)
    with open(p_clsnames_cn, encoding='UTF-8') as f:  # 设置文件对象
        class_names_cn = f.readlines()
    return class_names, class_names_cn


if __name__ == "__main__":

    # config
    path_state_dict_18 = os.path.join(BASE_DIR, "..", "data", "resnet18-5c106cde.pth")
    path_state_dict_50 = os.path.join(BASE_DIR, "..", "data", "resnet50-19c8e357.pth")
    path_img = os.path.join(BASE_DIR, "..", "data","Golden Retriever from baidu.jpg")
    # path_img = os.path.join(BASE_DIR, "..", "data", "tiger cat.jpg")
    path_classnames = os.path.join(BASE_DIR, "..", "data", "imagenet1000.json")
    path_classnames_cn = os.path.join(BASE_DIR, "..", "data", "imagenet_classnames.txt")

    # load class names
    cls_n, cls_n_cn = load_class_names(path_classnames, path_classnames_cn)

    # 1/5 load img
    img_tensor, img_rgb = process_img(path_img)

    # 2/5 load model
    resnet_model = get_resnet_18(path_state_dict_18, device, True)
    # resnet_model = get_resnet_18(path_state_dict_50, device, True)

    # 3/5 inference  tensor --> vector
    with torch.no_grad():
        time_tic = time.time()
        outputs = resnet_model(img_tensor)
        time_toc = time.time()

    # 4/5 index to class names
    _, pred_int = torch.max(outputs.data, 1)
    _, top5_idx = torch.topk(outputs.data, 5, dim=1)

    pred_idx = int(pred_int.cpu().numpy())
    pred_str, pred_cn = cls_n[pred_idx], cls_n_cn[pred_idx]
    print("img: {} is: {}\n{}".format(os.path.basename(path_img), pred_str, pred_cn))
    print("time consuming:{:.2f}s".format(time_toc - time_tic))

    # 5/5 visualization
    plt.imshow(img_rgb)
    plt.title("predict:{}".format(pred_str))
    top5_num = top5_idx.cpu().numpy().squeeze()
    text_str = [cls_n[t] for t in top5_num]
    for idx in range(len(top5_num)):
        plt.text(5, 15+idx*30, "top {}:{}".format(idx+1, text_str[idx]), bbox=dict(fc='yellow'))
    plt.show()

resnet训练程序

import os
from datetime import datetime
import numpy as np
import torch.nn as nn
import torch
from torch.utils.data import DataLoader
import torchvision.transforms as transforms
import torch.optim as optim
from tools.cifar10_dataset import CifarDataset
from tools.resnet import resnet56, resnet20
from tools.common_tools import ModelTrainer, show_confMat, plot_line

BASE_DIR = os.path.dirname(os.path.abspath(__file__))
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")


if __name__ == "__main__":

    # config
    train_dir = os.path.join(BASE_DIR, "..", "..", "Data", "cifar-10",  "cifar10_train")
    test_dir = os.path.join(BASE_DIR, "..", "..", "Data", "cifar-10", "cifar10_test")

    now_time = datetime.now()
    time_str = datetime.strftime(now_time, '%m-%d_%H-%M')
    log_dir = os.path.join(BASE_DIR, "..", "results", time_str)
    if not os.path.exists(log_dir):
        os.makedirs(log_dir)

    class_names = ('plane', 'car', 'bird', 'cat', 'deer', 'dog', 'frog', 'horse', 'ship', 'truck')

    num_classes = 10

    MAX_EPOCH = 182     # 182     # 64000 / (45000 / 128) = 182 epochs
    BATCH_SIZE = 128
    LR = 0.1
    log_interval = 1
    val_interval = 1
    start_epoch = -1
    milestones = [92, 136]  # divide it by 10 at 32k and 48k iterations

    # ============================ step 1/5 数据 ============================
    norm_mean = [0.485, 0.456, 0.406]
    norm_std = [0.229, 0.224, 0.225]

    train_transform = transforms.Compose([
        transforms.Resize(32),
        transforms.RandomHorizontalFlip(p=0.5),
        transforms.RandomCrop(32, padding=4),
        transforms.ToTensor(),
        transforms.Normalize(norm_mean, norm_std),
    ])

    valid_transform = transforms.Compose([
        transforms.Resize((32, 32)),
        transforms.ToTensor(),
        transforms.Normalize(norm_mean, norm_std),
    ])

    # 构建MyDataset实例
    train_data = CifarDataset(data_dir=train_dir, transform=train_transform)
    valid_data = CifarDataset(data_dir=test_dir, transform=valid_transform)

    # 构建DataLoder
    train_loader = DataLoader(dataset=train_data, batch_size=BATCH_SIZE, shuffle=True, num_workers=2)
    valid_loader = DataLoader(dataset=valid_data, batch_size=BATCH_SIZE, num_workers=2)

    # ============================ step 2/5 模型 ============================
    resnet_model = resnet20()

    resnet_model.to(device)
    # ============================ step 3/5 损失函数 ============================
    criterion = nn.CrossEntropyLoss()
    # ============================ step 4/5 优化器 ============================
    # 冻结卷积层
    optimizer = optim.SGD(resnet_model.parameters(), lr=LR, momentum=0.9, weight_decay=1e-4)  # 选择优化器

    scheduler = optim.lr_scheduler.MultiStepLR(optimizer, gamma=0.1, milestones=milestones)

# ============================ step 5/5 训练 ============================
    loss_rec = {"train": [], "valid": []}
    acc_rec = {"train": [], "valid": []}
    best_acc, best_epoch = 0, 0

    for epoch in range(start_epoch + 1, MAX_EPOCH):

        # 训练(data_loader, model, loss_f, optimizer, epoch_id, device, max_epoch)
        loss_train, acc_train, mat_train = ModelTrainer.train(train_loader, resnet_model, criterion, optimizer, epoch, device, MAX_EPOCH)
        loss_valid, acc_valid, mat_valid = ModelTrainer.valid(valid_loader, resnet_model, criterion, device)
        print("Epoch[{:0>3}/{:0>3}] Train Acc: {:.2%} Valid Acc:{:.2%} Train loss:{:.4f} Valid loss:{:.4f} LR:{}".format(
            epoch + 1, MAX_EPOCH, acc_train, acc_valid, loss_train, loss_valid, optimizer.param_groups[0]["lr"]))

        scheduler.step()  # 更新学习率

        # 绘图
        loss_rec["train"].append(loss_train), loss_rec["valid"].append(loss_valid)
        acc_rec["train"].append(acc_train), acc_rec["valid"].append(acc_valid)

        show_confMat(mat_train, class_names, "train", log_dir, verbose=epoch == MAX_EPOCH-1)
        show_confMat(mat_valid, class_names, "valid", log_dir, verbose=epoch == MAX_EPOCH-1)

        plt_x = np.arange(1, epoch+2)
        plot_line(plt_x, loss_rec["train"], plt_x, loss_rec["valid"], mode="loss", out_dir=log_dir)
        plot_line(plt_x, acc_rec["train"], plt_x, acc_rec["valid"], mode="acc", out_dir=log_dir)

        if epoch > (MAX_EPOCH/2) and best_acc < acc_valid:
            best_acc = acc_valid
            best_epoch = epoch

            checkpoint = {"model_state_dict": resnet_model.state_dict(),
                      "optimizer_state_dict": optimizer.state_dict(),
                      "epoch": epoch,
                      "best_acc": best_acc}

            path_checkpoint = os.path.join(log_dir, "checkpoint_best.pkl")
            torch.save(checkpoint, path_checkpoint)

    print(" done ~~~~ {}, best acc: {} in :{} epochs. ".format(datetime.strftime(datetime.now(), '%m-%d_%H-%M'),
                                                      best_acc, best_epoch))
    now_time = datetime.now()
    time_str = datetime.strftime(now_time, '%m-%d_%H-%M')
    print(time_str)

resnet网络结构程序

def conv3x3(in_planes, out_planes, stride=1, groups=1, dilation=1):
    """3x3 convolution with padding"""
    return nn.Conv2d(in_planes, out_planes, kernel_size=3, stride=stride,
                     padding=dilation, groups=groups, bias=False, dilation=dilation)


def conv1x1(in_planes, out_planes, stride=1):
    """1x1 convolution"""
    return nn.Conv2d(in_planes, out_planes, kernel_size=1, stride=stride, bias=False)


class BasicBlock(nn.Module):
    expansion = 1

    def __init__(self, inplanes, planes, stride=1, downsample=None, groups=1,
                 base_width=64, dilation=1, norm_layer=None):
        super(BasicBlock, self).__init__()
        if norm_layer is None:
            norm_layer = nn.BatchNorm2d
        if groups != 1 or base_width != 64:
            raise ValueError('BasicBlock only supports groups=1 and base_width=64')
        if dilation > 1:
            raise NotImplementedError("Dilation > 1 not supported in BasicBlock")
        # Both self.conv1 and self.downsample layers downsample the input when stride != 1
        self.conv1 = conv3x3(inplanes, planes, stride)
        self.bn1 = norm_layer(planes)
        self.relu = nn.ReLU(inplace=True)
        self.conv2 = conv3x3(planes, planes)
        self.bn2 = norm_layer(planes)
        self.downsample = downsample
        self.stride = stride

    def forward(self, x):
        identity = x

        out = self.conv1(x)
        out = self.bn1(out)
        out = self.relu(out)

        out = self.conv2(out)
        out = self.bn2(out)

        if self.downsample is not None:
            identity = self.downsample(x)

        out += identity
        out = self.relu(out)

        return out


class Bottleneck(nn.Module):
    # Bottleneck in torchvision places the stride for downsampling at 3x3 convolution(self.conv2)
    # while original implementation places the stride at the first 1x1 convolution(self.conv1)
    # according to "Deep residual learning for image recognition"https://arxiv.org/abs/1512.03385.
    # This variant is also known as ResNet V1.5 and improves accuracy according to
    # https://ngc.nvidia.com/catalog/model-scripts/nvidia:resnet_50_v1_5_for_pytorch.

    expansion = 4

    def __init__(self, inplanes, planes, stride=1, downsample=None, groups=1,
                 base_width=64, dilation=1, norm_layer=None):
        super(Bottleneck, self).__init__()
        if norm_layer is None:
            norm_layer = nn.BatchNorm2d
        width = int(planes * (base_width / 64.)) * groups
        # Both self.conv2 and self.downsample layers downsample the input when stride != 1
        self.conv1 = conv1x1(inplanes, width)
        self.bn1 = norm_layer(width)
        self.conv2 = conv3x3(width, width, stride, groups, dilation)
        self.bn2 = norm_layer(width)
        self.conv3 = conv1x1(width, planes * self.expansion)
        self.bn3 = norm_layer(planes * self.expansion)
        self.relu = nn.ReLU(inplace=True)
        self.downsample = downsample
        self.stride = stride

    def forward(self, x):
        identity = x

        out = self.conv1(x)
        out = self.bn1(out)
        out = self.relu(out)

        out = self.conv2(out)
        out = self.bn2(out)
        out = self.relu(out)

        out = self.conv3(out)
        out = self.bn3(out)

        if self.downsample is not None:
            identity = self.downsample(x)

        out += identity
        out = self.relu(out)

        return out


class ResNet(nn.Module):

    def __init__(self, block, layers, num_classes=1000, zero_init_residual=False,
                 groups=1, width_per_group=64, replace_stride_with_dilation=None,
                 norm_layer=None):
        super(ResNet, self).__init__()
        if norm_layer is None:
            norm_layer = nn.BatchNorm2d
        self._norm_layer = norm_layer

        self.inplanes = 64
        self.dilation = 1
        if replace_stride_with_dilation is None:
            # each element in the tuple indicates if we should replace
            # the 2x2 stride with a dilated convolution instead
            replace_stride_with_dilation = [False, False, False]
        if len(replace_stride_with_dilation) != 3:
            raise ValueError("replace_stride_with_dilation should be None "
                             "or a 3-element tuple, got {}".format(replace_stride_with_dilation))
        self.groups = groups
        self.base_width = width_per_group
        self.conv1 = nn.Conv2d(3, self.inplanes, kernel_size=7, stride=2, padding=3,
                               bias=False)
        self.bn1 = norm_layer(self.inplanes)
        self.relu = nn.ReLU(inplace=True)
        self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
        self.layer1 = self._make_layer(block, 64, layers[0])
        self.layer2 = self._make_layer(block, 128, layers[1], stride=2,
                                       dilate=replace_stride_with_dilation[0])
        self.layer3 = self._make_layer(block, 256, layers[2], stride=2,
                                       dilate=replace_stride_with_dilation[1])
        self.layer4 = self._make_layer(block, 512, layers[3], stride=2,
                                       dilate=replace_stride_with_dilation[2])
        self.avgpool = nn.AdaptiveAvgPool2d((1, 1))
        self.fc = nn.Linear(512 * block.expansion, num_classes)

        for m in self.modules():
            if isinstance(m, nn.Conv2d):
                nn.init.kaiming_normal_(m.weight, mode='fan_out', nonlinearity='relu')
            elif isinstance(m, (nn.BatchNorm2d, nn.GroupNorm)):
                nn.init.constant_(m.weight, 1)
                nn.init.constant_(m.bias, 0)

        # Zero-initialize the last BN in each residual branch,
        # so that the residual branch starts with zeros, and each residual block behaves like an identity.
        # This improves the model by 0.2~0.3% according to https://arxiv.org/abs/1706.02677
        if zero_init_residual:
            for m in self.modules():
                if isinstance(m, Bottleneck):
                    nn.init.constant_(m.bn3.weight, 0)
                elif isinstance(m, BasicBlock):
                    nn.init.constant_(m.bn2.weight, 0)

    def _make_layer(self, block, planes, blocks, stride=1, dilate=False):
        norm_layer = self._norm_layer
        downsample = None
        previous_dilation = self.dilation
        if dilate:
            self.dilation *= stride
            stride = 1
        if stride != 1 or self.inplanes != planes * block.expansion:
            downsample = nn.Sequential(
                conv1x1(self.inplanes, planes * block.expansion, stride),
                norm_layer(planes * block.expansion),
            )

        layers = []
        layers.append(block(self.inplanes, planes, stride, downsample, self.groups,
                            self.base_width, previous_dilation, norm_layer))
        self.inplanes = planes * block.expansion
        for _ in range(1, blocks):
            layers.append(block(self.inplanes, planes, groups=self.groups,
                                base_width=self.base_width, dilation=self.dilation,
                                norm_layer=norm_layer))

        return nn.Sequential(*layers)

    def _forward_impl(self, x):
        # See note [TorchScript super()]
        x = self.conv1(x)
        x = self.bn1(x)
        x = self.relu(x)
        x = self.maxpool(x)

        x = self.layer1(x)
        x = self.layer2(x)
        x = self.layer3(x)
        x = self.layer4(x)

        x = self.avgpool(x)
        x = torch.flatten(x, 1)
        x = self.fc(x)

        return x

    def forward(self, x):
        return self._forward_impl(x)


def _resnet(arch, block, layers, pretrained, progress, **kwargs):
    model = ResNet(block, layers, **kwargs)
    if pretrained:
        state_dict = load_state_dict_from_url(model_urls[arch],
                                              progress=progress)
        model.load_state_dict(state_dict)
    return model