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【深度学习项目三】ResNet50多分类任务【十二生肖分类】

2023-02-18 16:36:20 时间

项目链接:https://aistudio.baidu.com/aistudio/projectdetail/1930877

1. 卷积神经网络简介

1.1 AlexNet

贡献:

  • 引入ReLU作为激活函数
  • Dropout层
  • Max Pooling
  • GPU加速
  • 数据增强(截取、水平翻转)

1.2 VGG

1.3 GoogleNet

全连接层对输入输出大小有限制,用池化层代替没有约束。

1.4 ResNet

  • 残差结构解决梯度消失问题,多个路径前向传播。
  • 层数改变如图左下角,主要是为了减少计算开销,既减少参数。

2. 数据集介绍

按照12生肖在网上”下载的12种动物照片

训练样本量| 7,096张

验证样本量| 639张

测试样本量| 656张

加载使用方式|自定义数据集

2.1 数据标注

数据集分为train、valid、test三个文件夹,每个文件夹内包含12个分类文件夹,每个分类文件夹内是具体的样本图片。

.
├── test|train|valid
│   ├── dog
│   ├── dragon
│   ├── goat
│   ├── horse
│   ├── monkey
│   ├── ox
│   ├── pig
│   ├── rabbit
│   ├── ratt
│   ├── rooster
│   ├── snake
│   └── tiger

我们对这些样本进行一个标注处理,最终生成train.txt/valid.txt/test.txt三个数据标注文件。

```python
config.py
__all__ = ['CONFIG', 'get']

CONFIG = {
    'model_save_dir': "./output/zodiac",
    'num_classes': 12,
    'total_images': 7096,
    'epochs': 20,
    'batch_size': 32,
    'image_shape': [3, 224, 224],
    'LEARNING_RATE': {
        'params': {
            'lr': 0.00375             
        }
    },
    'OPTIMIZER': {
        'params': {
            'momentum': 0.9
        },
        'regularizer': {
            'function': 'L2',
            'factor': 0.000001
        }
    },
    'LABEL_MAP': [
        "ratt",
        "ox",
        "tiger",
        "rabbit",
        "dragon",
        "snake",
        "horse",
        "goat",
        "monkey",
        "rooster",
        "dog",
        "pig",
    ]
}

def get(full_path):
    for id, name in enumerate(full_path.split('.')):
        if id == 0:
            config = CONFIG
        
        config = config[name]
    
    return config
import io
import os
from PIL import Image
from config import get


# 数据集根目录
DATA_ROOT = 'signs'

# 标签List
LABEL_MAP = get('LABEL_MAP')

# 标注生成函数
def generate_annotation(mode):
    # 建立标注文件
    with open('{}/{}.txt'.format(DATA_ROOT, mode), 'w') as f:
        # 对应每个用途的数据文件夹,train/valid/test
        train_dir = '{}/{}'.format(DATA_ROOT, mode)

        # 遍历文件夹,获取里面的分类文件夹
        for path in os.listdir(train_dir):
            # 标签对应的数字索引,实际标注的时候直接使用数字索引
            label_index = LABEL_MAP.index(path)

            # 图像样本所在的路径
            image_path = '{}/{}'.format(train_dir, path)

            # 遍历所有图像
            for image in os.listdir(image_path):
                # 图像完整路径和名称
                image_file = '{}/{}'.format(image_path, image)
                
                try:
                    # 验证图片格式是否ok
                    with open(image_file, 'rb') as f_img:
                        image = Image.open(io.BytesIO(f_img.read()))
                        image.load()
                        
                        if image.mode == 'RGB':
                            f.write('{}\t{}\n'.format(image_file, label_index))
                except:
                    continue


generate_annotation('train')  # 生成训练集标注文件
generate_annotation('valid')  # 生成验证集标注文件
generate_annotation('test')   # 生成测试集标注文件

2.2 数据集定义

接下来我们使用标注好的文件进行数据集类的定义,方便后续模型训练使用。

2.2.1 导入相关库

import paddle
import numpy as np
from config import get

HWC和CHW区别

  • C代表:输入通道数
  • H/W分别代表图片的高、宽

NCHW

  • N代表样本数

to_tensor

paddle.vision.transforms.to_tensor(pic, data_format=‘CHW’)[源代码]

将 PIL.Image 或 numpy.ndarray 转换成 paddle.Tensor。

  • 形状为 (H x W x C)的输入数据 PIL.Image 或 numpy.ndarray 转换为 (C x H x W)。 如果想保持形状不变,可以将参数 data_format 设置为 ‘HWC’。
  • 同时,如果输入的 PIL.Image 的 mode 是 (L, LA, P, I, F, RGB, YCbCr, RGBA, CMYK, 1) 其中一种,或者输入的 numpy.ndarray 数据类型是 ‘uint8’,那个会将输入数据从(0-255)的范围缩放到 (0-1)的范围。其他的情况,则保持输入不变。

2.2.2 导入数据集的定义实现

我们数据集的代码实现是在dataset.py中。

import paddle
import paddle.vision.transforms as T
import numpy as np
from config import get
from PIL import Image

__all__ = ['ZodiacDataset']

# 定义图像的大小
image_shape = get('image_shape') #'image_shape': [3, 224, 224],
IMAGE_SIZE = (image_shape[1], image_shape[2])


class ZodiacDataset(paddle.io.Dataset):
    """
    十二生肖数据集类的定义
    """

    def __init__(self, mode='train'):
        """
        初始化函数
        """
        assert mode in ['train', 'test', 'valid'], 'mode is one of train, test, valid.' #判断参数合法性
       

        self.data = []
         """
        根据不同模式选择不同的数据标注文件
        
        """
        with open('signs/{}.txt'.format(mode)) as f:
            for line in f.readlines():
                info = line.strip().split('\t')

                if len(info) > 0:
                    self.data.append([info[0].strip(), info[1].strip()])#进行切分形成数组,每个数组包含图像的地址和label

        if mode == 'train':
            self.transforms = T.Compose([
                T.RandomResizedCrop(IMAGE_SIZE),    # 随机裁剪大小,裁剪地方不同等于间接增加了数据样本 300*300-224*224
                T.RandomHorizontalFlip(0.5),        # 随机水平翻转,概率0.5,也是等于得到一个新的图像
                T.ToTensor(),                       # 数据的格式转换和标准化 HWC => CHW  
                T.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])  # 图像归一化
            ])
        else:  #评估模式:没必要进行水平翻转增加样本量了,主要是想看看效果
            self.transforms = T.Compose([
                T.Resize(256),                 # 图像大小修改
                T.RandomCrop(IMAGE_SIZE),      # 随机裁剪,
                T.ToTensor(),                  # 数据的格式转换和标准化 HWC => CHW
                T.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])   # 图像归一化
            ])
        
    def __getitem__(self, index):
        """
        根据索引获取单个样本
        """
        image_file, label = self.data[index]
        image = Image.open(image_file)
#转成RGB模式,三通道的
        if image.mode != 'RGB':
            image = image.convert('RGB')

        image = self.transforms(image)#得到预处理后的结果

        return image, np.array(label, dtype='int64')#对label做个数据转换,int类型转成numpy

    def __len__(self):
        """
        获取样本总数
        """
        return len(self.data)
from dataset import ZodiacDataset

2.3.3 实例化数据集类

根据所使用的数据集需求实例化数据集类,并查看总样本量。

train_dataset = ZodiacDataset(mode='train')
valid_dataset = ZodiacDataset(mode='valid')

print('训练数据集:{}张;验证数据集:{}张'.format(len(train_dataset), len(valid_dataset)))

3.模型选择和开发

3.1 网络构建

本次我们使用ResNet50网络来完成我们的案例实践。

1)ResNet系列网络

2)ResNet50结构

3)残差区块

4)ResNet其他版本

network = paddle.vision.models.resnet50(num_classes=get('num_classes'), pretrained=True)
#pretrained=True使用别人已经训练好的预训练模型进行训练网络
model = paddle.Model(network)
model.summary((-1, ) + tuple(get('image_shape')))
-------------------------------------------------------------------------------
   Layer (type)         Input Shape          Output Shape         Param #    
===============================================================================
     Conv2D-1        [[1, 3, 224, 224]]   [1, 64, 112, 112]        9,408     
   BatchNorm2D-1    [[1, 64, 112, 112]]   [1, 64, 112, 112]         256      
      ReLU-1        [[1, 64, 112, 112]]   [1, 64, 112, 112]          0       
    MaxPool2D-1     [[1, 64, 112, 112]]    [1, 64, 56, 56]           0       
     Conv2D-3        [[1, 64, 56, 56]]     [1, 64, 56, 56]         4,096     
   BatchNorm2D-3     [[1, 64, 56, 56]]     [1, 64, 56, 56]          256      
      ReLU-2         [[1, 256, 56, 56]]    [1, 256, 56, 56]          0       
     Conv2D-4        [[1, 64, 56, 56]]     [1, 64, 56, 56]        36,864     
   BatchNorm2D-4     [[1, 64, 56, 56]]     [1, 64, 56, 56]          256      
     Conv2D-5        [[1, 64, 56, 56]]     [1, 256, 56, 56]       16,384     
   BatchNorm2D-5     [[1, 256, 56, 56]]    [1, 256, 56, 56]        1,024     
     Conv2D-2        [[1, 64, 56, 56]]     [1, 256, 56, 56]       16,384     
   BatchNorm2D-2     [[1, 256, 56, 56]]    [1, 256, 56, 56]        1,024     
 BottleneckBlock-1   [[1, 64, 56, 56]]     [1, 256, 56, 56]          0       
     Conv2D-6        [[1, 256, 56, 56]]    [1, 64, 56, 56]        16,384     
   BatchNorm2D-6     [[1, 64, 56, 56]]     [1, 64, 56, 56]          256      
      ReLU-3         [[1, 256, 56, 56]]    [1, 256, 56, 56]          0       
     Conv2D-7        [[1, 64, 56, 56]]     [1, 64, 56, 56]        36,864     
   BatchNorm2D-7     [[1, 64, 56, 56]]     [1, 64, 56, 56]          256      
     Conv2D-8        [[1, 64, 56, 56]]     [1, 256, 56, 56]       16,384     
   BatchNorm2D-8     [[1, 256, 56, 56]]    [1, 256, 56, 56]        1,024     
 BottleneckBlock-2   [[1, 256, 56, 56]]    [1, 256, 56, 56]          0       
     Conv2D-9        [[1, 256, 56, 56]]    [1, 64, 56, 56]        16,384     
   BatchNorm2D-9     [[1, 64, 56, 56]]     [1, 64, 56, 56]          256      
      ReLU-4         [[1, 256, 56, 56]]    [1, 256, 56, 56]          0       
     Conv2D-10       [[1, 64, 56, 56]]     [1, 64, 56, 56]        36,864     
  BatchNorm2D-10     [[1, 64, 56, 56]]     [1, 64, 56, 56]          256      
     Conv2D-11       [[1, 64, 56, 56]]     [1, 256, 56, 56]       16,384     
  BatchNorm2D-11     [[1, 256, 56, 56]]    [1, 256, 56, 56]        1,024     
 BottleneckBlock-3   [[1, 256, 56, 56]]    [1, 256, 56, 56]          0       
     Conv2D-13       [[1, 256, 56, 56]]    [1, 128, 56, 56]       32,768     
  BatchNorm2D-13     [[1, 128, 56, 56]]    [1, 128, 56, 56]         512      
      ReLU-5         [[1, 512, 28, 28]]    [1, 512, 28, 28]          0       
     Conv2D-14       [[1, 128, 56, 56]]    [1, 128, 28, 28]       147,456    
  BatchNorm2D-14     [[1, 128, 28, 28]]    [1, 128, 28, 28]         512      
     Conv2D-15       [[1, 128, 28, 28]]    [1, 512, 28, 28]       65,536     
  BatchNorm2D-15     [[1, 512, 28, 28]]    [1, 512, 28, 28]        2,048     
     Conv2D-12       [[1, 256, 56, 56]]    [1, 512, 28, 28]       131,072    
  BatchNorm2D-12     [[1, 512, 28, 28]]    [1, 512, 28, 28]        2,048     
 BottleneckBlock-4   [[1, 256, 56, 56]]    [1, 512, 28, 28]          0       
     Conv2D-16       [[1, 512, 28, 28]]    [1, 128, 28, 28]       65,536     
  BatchNorm2D-16     [[1, 128, 28, 28]]    [1, 128, 28, 28]         512      
      ReLU-6         [[1, 512, 28, 28]]    [1, 512, 28, 28]          0       
     Conv2D-17       [[1, 128, 28, 28]]    [1, 128, 28, 28]       147,456    
  BatchNorm2D-17     [[1, 128, 28, 28]]    [1, 128, 28, 28]         512      
     Conv2D-18       [[1, 128, 28, 28]]    [1, 512, 28, 28]       65,536     
  BatchNorm2D-18     [[1, 512, 28, 28]]    [1, 512, 28, 28]        2,048     
 BottleneckBlock-5   [[1, 512, 28, 28]]    [1, 512, 28, 28]          0       
     Conv2D-19       [[1, 512, 28, 28]]    [1, 128, 28, 28]       65,536     
  BatchNorm2D-19     [[1, 128, 28, 28]]    [1, 128, 28, 28]         512      
      ReLU-7         [[1, 512, 28, 28]]    [1, 512, 28, 28]          0       
     Conv2D-20       [[1, 128, 28, 28]]    [1, 128, 28, 28]       147,456    
  BatchNorm2D-20     [[1, 128, 28, 28]]    [1, 128, 28, 28]         512      
     Conv2D-21       [[1, 128, 28, 28]]    [1, 512, 28, 28]       65,536     
  BatchNorm2D-21     [[1, 512, 28, 28]]    [1, 512, 28, 28]        2,048     
 BottleneckBlock-6   [[1, 512, 28, 28]]    [1, 512, 28, 28]          0       
     Conv2D-22       [[1, 512, 28, 28]]    [1, 128, 28, 28]       65,536     
  BatchNorm2D-22     [[1, 128, 28, 28]]    [1, 128, 28, 28]         512      
      ReLU-8         [[1, 512, 28, 28]]    [1, 512, 28, 28]          0       
     Conv2D-23       [[1, 128, 28, 28]]    [1, 128, 28, 28]       147,456    
  BatchNorm2D-23     [[1, 128, 28, 28]]    [1, 128, 28, 28]         512      
     Conv2D-24       [[1, 128, 28, 28]]    [1, 512, 28, 28]       65,536     
  BatchNorm2D-24     [[1, 512, 28, 28]]    [1, 512, 28, 28]        2,048     
 BottleneckBlock-7   [[1, 512, 28, 28]]    [1, 512, 28, 28]          0       
     Conv2D-26       [[1, 512, 28, 28]]    [1, 256, 28, 28]       131,072    
  BatchNorm2D-26     [[1, 256, 28, 28]]    [1, 256, 28, 28]        1,024     
      ReLU-9        [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-27       [[1, 256, 28, 28]]    [1, 256, 14, 14]       589,824    
  BatchNorm2D-27     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
     Conv2D-28       [[1, 256, 14, 14]]   [1, 1024, 14, 14]       262,144    
  BatchNorm2D-28    [[1, 1024, 14, 14]]   [1, 1024, 14, 14]        4,096     
     Conv2D-25       [[1, 512, 28, 28]]   [1, 1024, 14, 14]       524,288    
  BatchNorm2D-25    [[1, 1024, 14, 14]]   [1, 1024, 14, 14]        4,096     
 BottleneckBlock-8   [[1, 512, 28, 28]]   [1, 1024, 14, 14]          0       
     Conv2D-29      [[1, 1024, 14, 14]]    [1, 256, 14, 14]       262,144    
  BatchNorm2D-29     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
      ReLU-10       [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-30       [[1, 256, 14, 14]]    [1, 256, 14, 14]       589,824    
  BatchNorm2D-30     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
     Conv2D-31       [[1, 256, 14, 14]]   [1, 1024, 14, 14]       262,144    
  BatchNorm2D-31    [[1, 1024, 14, 14]]   [1, 1024, 14, 14]        4,096     
 BottleneckBlock-9  [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-32      [[1, 1024, 14, 14]]    [1, 256, 14, 14]       262,144    
  BatchNorm2D-32     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
      ReLU-11       [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-33       [[1, 256, 14, 14]]    [1, 256, 14, 14]       589,824    
  BatchNorm2D-33     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
     Conv2D-34       [[1, 256, 14, 14]]   [1, 1024, 14, 14]       262,144    
  BatchNorm2D-34    [[1, 1024, 14, 14]]   [1, 1024, 14, 14]        4,096     
BottleneckBlock-10  [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-35      [[1, 1024, 14, 14]]    [1, 256, 14, 14]       262,144    
  BatchNorm2D-35     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
      ReLU-12       [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-36       [[1, 256, 14, 14]]    [1, 256, 14, 14]       589,824    
  BatchNorm2D-36     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
     Conv2D-37       [[1, 256, 14, 14]]   [1, 1024, 14, 14]       262,144    
  BatchNorm2D-37    [[1, 1024, 14, 14]]   [1, 1024, 14, 14]        4,096     
BottleneckBlock-11  [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-38      [[1, 1024, 14, 14]]    [1, 256, 14, 14]       262,144    
  BatchNorm2D-38     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
      ReLU-13       [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-39       [[1, 256, 14, 14]]    [1, 256, 14, 14]       589,824    
  BatchNorm2D-39     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
     Conv2D-40       [[1, 256, 14, 14]]   [1, 1024, 14, 14]       262,144    
  BatchNorm2D-40    [[1, 1024, 14, 14]]   [1, 1024, 14, 14]        4,096     
BottleneckBlock-12  [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-41      [[1, 1024, 14, 14]]    [1, 256, 14, 14]       262,144    
  BatchNorm2D-41     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
      ReLU-14       [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-42       [[1, 256, 14, 14]]    [1, 256, 14, 14]       589,824    
  BatchNorm2D-42     [[1, 256, 14, 14]]    [1, 256, 14, 14]        1,024     
     Conv2D-43       [[1, 256, 14, 14]]   [1, 1024, 14, 14]       262,144    
  BatchNorm2D-43    [[1, 1024, 14, 14]]   [1, 1024, 14, 14]        4,096     
BottleneckBlock-13  [[1, 1024, 14, 14]]   [1, 1024, 14, 14]          0       
     Conv2D-45      [[1, 1024, 14, 14]]    [1, 512, 14, 14]       524,288    
  BatchNorm2D-45     [[1, 512, 14, 14]]    [1, 512, 14, 14]        2,048     
      ReLU-15        [[1, 2048, 7, 7]]     [1, 2048, 7, 7]           0       
     Conv2D-46       [[1, 512, 14, 14]]     [1, 512, 7, 7]       2,359,296   
  BatchNorm2D-46      [[1, 512, 7, 7]]      [1, 512, 7, 7]         2,048     
     Conv2D-47        [[1, 512, 7, 7]]     [1, 2048, 7, 7]       1,048,576   
  BatchNorm2D-47     [[1, 2048, 7, 7]]     [1, 2048, 7, 7]         8,192     
     Conv2D-44      [[1, 1024, 14, 14]]    [1, 2048, 7, 7]       2,097,152   
  BatchNorm2D-44     [[1, 2048, 7, 7]]     [1, 2048, 7, 7]         8,192     
BottleneckBlock-14  [[1, 1024, 14, 14]]    [1, 2048, 7, 7]           0       
     Conv2D-48       [[1, 2048, 7, 7]]      [1, 512, 7, 7]       1,048,576   
  BatchNorm2D-48      [[1, 512, 7, 7]]      [1, 512, 7, 7]         2,048     
      ReLU-16        [[1, 2048, 7, 7]]     [1, 2048, 7, 7]           0       
     Conv2D-49        [[1, 512, 7, 7]]      [1, 512, 7, 7]       2,359,296   
  BatchNorm2D-49      [[1, 512, 7, 7]]      [1, 512, 7, 7]         2,048     
     Conv2D-50        [[1, 512, 7, 7]]     [1, 2048, 7, 7]       1,048,576   
  BatchNorm2D-50     [[1, 2048, 7, 7]]     [1, 2048, 7, 7]         8,192     
BottleneckBlock-15   [[1, 2048, 7, 7]]     [1, 2048, 7, 7]           0       
     Conv2D-51       [[1, 2048, 7, 7]]      [1, 512, 7, 7]       1,048,576   
  BatchNorm2D-51      [[1, 512, 7, 7]]      [1, 512, 7, 7]         2,048     
      ReLU-17        [[1, 2048, 7, 7]]     [1, 2048, 7, 7]           0       
     Conv2D-52        [[1, 512, 7, 7]]      [1, 512, 7, 7]       2,359,296   
  BatchNorm2D-52      [[1, 512, 7, 7]]      [1, 512, 7, 7]         2,048     
     Conv2D-53        [[1, 512, 7, 7]]     [1, 2048, 7, 7]       1,048,576   
  BatchNorm2D-53     [[1, 2048, 7, 7]]     [1, 2048, 7, 7]         8,192     
BottleneckBlock-16   [[1, 2048, 7, 7]]     [1, 2048, 7, 7]           0       
AdaptiveAvgPool2D-1  [[1, 2048, 7, 7]]     [1, 2048, 1, 1]           0       
     Linear-1           [[1, 2048]]            [1, 12]            24,588     
===============================================================================
Total params: 23,585,740
Trainable params: 23,479,500
Non-trainable params: 106,240
-------------------------------------------------------------------------------
Input size (MB): 0.57
Forward/backward pass size (MB): 261.48
Params size (MB): 89.97
Estimated Total Size (MB): 352.02
-------------------------------------------------------------------------------

{'total_params': 23585740, 'trainable_params': 23479500}

4.模型训练和优化

CosineAnnealingDecay

class paddle.optimizer.lr.CosineAnnealingDecay(learningrate, Tmax, etamin=0, lastepoch=- 1, verbose=False)[源代码]

该接口使用 cosine annealing 的策略来动态调整学习率。

\begin{aligned} \eta_{t} &=\eta_{\min }+\frac{1}{2}\left(\eta_{\max }-\eta_{\min }\right)\left(1+\cos \left(\frac{T_{c u r}}{T_{\max }} \pi\right)\right), & T_{c u r} \neq(2 k+1) T_{\max } \\ \eta_{t+1} &=\eta_{t}+\frac{1}{2}\left(\eta_{\max }-\eta_{\min }\right)\left(1-\cos \left(\frac{1}{T_{\max }} \pi\right)\right), & T_{c u r}=(2 k+1) T_{\max } \end{aligned}

ηmax 的初始值为 learning_rate, Tcur 是SGDR(重启训练SGD)训练过程中的当前训练轮数。SGDR的训练方法可以参考文档 SGDR: Stochastic Gradient Descent with Warm Restarts. 这里只是实现了 cosine annealing 动态学习率,热启训练部分没有实现。

参数:

  • learning_rate (float) - 初始学习率,也就是公式中的 ηmax ,数据类型为Python float。
  • T_max (float|int) - 训练的上限轮数,是余弦衰减周期的一半
  • eta_min (float|int, 可选) - 学习率的最小值,即公式中的 ηmin 。默认值为0。
  • last_epoch (int,可选) - 上一轮的轮数,重启训练时设置为上一轮的epoch数。默认值为 -1,则为初始学习率。
  • verbose (bool,可选) - 如果是 True ,则在每一轮更新时在标准输出 stdout 输出一条信息。默认值为 False

返回:用于调整学习率的 CosineAnnealingDecay 实例对象

Momentum

class paddle.optimizer.Momentum(learningrate=0.001, momentum=0.9, parameters=None, usenesterov=False, weightdecay=None, gradclip=None, name=None)[源代码]

该接口实现含有速度状态的Simple Momentum 优化器 该优化器含有牛顿动量标志,公式更新如下: 更新公式如下:

参数:

  • learning_rate (float|_LRScheduler, 可选) - 学习率,用于参数更新的计算。可以是一个浮点型值或者一个_LRScheduler类,默认值为0.001
  • momentum (float, 可选) - 动量因子
  • parameters (list, 可选) -指定优化器需要优化的参数。在动态图模式下必须提供该参数;在静态图模式下默认值为None,这时所有的参数都将被优化。
  • use_nesterov (bool, 可选) - 赋能牛顿动量,默认值False。
  • weight_decay (float|Tensor, 可选) - 权重衰减系数,是一个float类型或者shape为[1] ,数据类型为float32的Tensor类型。默认值为0.01
  • grad_clip (GradientClipBase, 可选) – 梯度裁剪的策略,支持三种裁剪策略: cn_api_fluid_clip_GradientClipByGlobalNorm 、 cn_api_fluid_clip_GradientClipByNorm 、 cn_api_fluid_clip_GradientClipByValue 。 默认值为None,此时将不进行梯度裁剪。
  • name (str, 可选)- 该参数供开发人员打印调试信息时使用,具体用法请参见 Name ,默认值为None

API参考链接 https://www.paddlepaddle.org.cn/documentation/docs/zh/api/paddle/optimizer/momentum/Momentum_cn.html

EPOCHS = get('epochs')
BATCH_SIZE = get('batch_size')

def create_optim(parameters):
    step_each_epoch = get('total_images') // get('batch_size')
    lr = paddle.optimizer.lr.CosineAnnealingDecay(learning_rate=get('LEARNING_RATE.params.lr'),
                                                  T_max=step_each_epoch * EPOCHS)

    return paddle.optimizer.Momentum(learning_rate=lr,
                                     parameters=parameters,
                                     weight_decay=paddle.regularizer.L2Decay(get('OPTIMIZER.regularizer.factor'))) #正则化来提升精度


# 模型训练配置
model.prepare(create_optim(network.parameters()),  # 优化器
              paddle.nn.CrossEntropyLoss(),        # 损失函数
              paddle.metric.Accuracy(topk=(1, 5))) # 评估指标

# 训练可视化VisualDL工具的回调函数
visualdl = paddle.callbacks.VisualDL(log_dir='visualdl_log')

# 启动模型全流程训练
model.fit(train_dataset,            # 训练数据集
          valid_dataset,            # 评估数据集
          epochs=EPOCHS,            # 总的训练轮次
          batch_size=BATCH_SIZE,    # 批次计算的样本量大小
          shuffle=True,             # 是否打乱样本集
          verbose=1,                # 日志展示格式
          save_dir='./chk_points/', # 分阶段的训练模型存储路径
          callbacks=[visualdl])     # 回调函数使用

top1 表示预测的第一个答案就是正确答案的准确率

top5 表示预测里面前五个包含正确答案的准确率

预测可视化:

4.1模型存储

将我们训练得到的模型进行保存,以便后续评估和测试使用。

model.save(get('model_save_dir'))

5 模型评估和测试

5.1 批量预测测试

5.1.1 测试数据集

predict_dataset = ZodiacDataset(mode='test')
print('测试数据集样本量:{}'.format(len(predict_dataset)))
from paddle.static import InputSpec

# 网络结构示例化
network = paddle.vision.models.resnet50(num_classes=get('num_classes'))

# 模型封装
model_2 = paddle.Model(network, inputs=[InputSpec(shape=[-1] + get('image_shape'), dtype='float32', name='image')])

# 训练好的模型加载
model_2.load(get('model_save_dir'))

# 模型配置
model_2.prepare()

# 执行预测
result = model_2.predict(predict_dataset)
import matplotlib.pyplot as plt
# 样本映射
LABEL_MAP = get('LABEL_MAP')

def show_img(img, predict):
    plt.figure()
    plt.title('predict: {}'.format(LABEL_MAP[predict_label]))
    image_file, label = predict_dataset.data[idx]
    image = Image.open(image_file)
    plt.imshow(image)
    plt.show()



# 随机取样本展示
indexs = [50,150 , 250, 350, 450, 00]

for idx in indexs:
    predict_label = np.argmax(result[0][idx])
    real_label = predict_dataset[idx][1]
    show_img(real_label,predict_label )
    print('样本ID:{}, 真实标签:{}, 预测值:{}'.format(idx, LABEL_MAP[real_label], LABEL_MAP[predict_label]))


#或者不定义函数:
"""
import matplotlib.pyplot as plt
# 样本映射
LABEL_MAP = get('LABEL_MAP')

# # 抽样展示
indexs = [50,150 , 250, 350, 450, 00]

for idx in indexs:
    predict_label = np.argmax(result[0][idx])
    real_label = predict_dataset[idx][1]
    print('样本ID:{}, 真实标签:{}, 预测值:{}'.format(idx, LABEL_MAP[real_label], LABEL_MAP[predict_label]))
    image_file, label = predict_dataset.data[idx]
    image = Image.open(image_file)
    plt.figure()
    plt.title('predict: {}'.format(LABEL_MAP[predict_label]))
    plt.imshow(image)
    plt.show()
"""

样本ID:50, 真实标签:monkey, 预测值:monkey

样本ID:150, 真实标签:ratt, 预测值:ratt

样本ID:450, 真实标签:tiger, 预测值:tiger

6 模型部署

model_2.save('infer/zodiac', training=False)

总结

  • 本次讲解了四种卷积神经网络的由来,以及采用resnet50实现了十二生肖分类项目
  • 本次项目重点在于数据集自定义、以及创建优化器。来使模型更加灵活可改动也提高准确率和有助于模型快速收敛。
  • 这里还是推荐模型封装不要采用高层api 自己用Sub Class写法或者用Sequential写法。尝试写写看虽然层数比较多!