第T8周:猫狗识别

105 阅读12分钟

要求:

  1. 了解model.train_on_batch()并运用
  2. 了解tqdm,并使用tqdm实现可视化进度条

拔高(可选):

  1. 本文代码中存在一个严重的BUG,请找出它并配以文字说明

探索(难度有点大)

  1. 修改代码,处理BUG

这篇文章中我放弃了以往的model.fit()训练方法,改用model.train_on_batch方法。两种方法的比较:

  • model.fit():用起来十分简单,对新手非常友好
  • model.train_on_batch():封装程度更低,可以玩更多花样。

此外我也引入了进度条的显示方式,更加方便我们及时查看模型训练过程中的情况,可以及时打印各项指标。

一、前期工作

1. 设置GPU

我的环境

  • 操作系统:CentOS7
  • 显卡:RTX3090 两张
  • 显卡驱动:550.78
  • CUDA版本: 12.4
  • 语言环境:Python3.9.19
  • 编译器:Jupyter Lab
  • 深度学习环境:
    • TensorFlow-2.17.0 (GPU版本)
import tensorflow as tf

gpus = tf.config.list_physical_devices("GPU")

if gpus:
    tf.config.experimental.set_memory_growth(gpus[0], True)  #设置GPU显存用量按需使用
    tf.config.set_visible_devices([gpus[0]],"GPU")

# 打印显卡信息,确认GPU可用
print(gpus)
[PhysicalDevice(name='/physical_device:GPU:0', device_type='GPU'), PhysicalDevice(name='/physical_device:GPU:1', device_type='GPU')]

2. 导入数据

import matplotlib.pyplot as plt
# 支持中文
plt.rcParams['font.sans-serif'] = ['SimHei']  # 用来正常显示中文标签
plt.rcParams['axes.unicode_minus'] = False  # 用来正常显示负号

import os,PIL,pathlib

#隐藏警告
import warnings
warnings.filterwarnings('ignore')

data_dir = "./data"
data_dir = pathlib.Path(data_dir)

image_count = len(list(data_dir.glob('*/*')))

print("图片总数为:",image_count)
图片总数为: 3400

二、数据预处理

1. 加载数据

batch_size = 8
img_height = 224
img_width = 224

"""
关于image_dataset_from_directory()的详细介绍可以参考文章:https://mtyjkh.blog.csdn.net/article/details/117018789
"""
train_ds = tf.keras.preprocessing.image_dataset_from_directory(
    data_dir,
    validation_split=0.2,
    subset="training",
    seed=12,
    image_size=(img_height, img_width),
    batch_size=batch_size)
Found 3400 files belonging to 2 classes.
Using 2720 files for training.
"""
关于image_dataset_from_directory()的详细介绍可以参考文章:https://mtyjkh.blog.csdn.net/article/details/117018789
"""
val_ds = tf.keras.preprocessing.image_dataset_from_directory(
    data_dir,
    validation_split=0.2,
    subset="validation",
    seed=12,
    image_size=(img_height, img_width),
    batch_size=batch_size)
Found 3400 files belonging to 2 classes.
Using 680 files for validation.
class_names = train_ds.class_names
print(class_names)
['cat', 'dog']
for image_batch, labels_batch in train_ds:
    print(image_batch.shape)
    print(labels_batch.shape)
    break
(8, 224, 224, 3)
(8,)
  • Image_batch是形状的张量(8, 224, 224, 3)。这是一批形状224x224x3的8张图片(最后一维指的是彩色通道RGB)。
  • Label_batch是形状(8,)的张量,这些标签对应8张图片

2. 配置数据集

  • shuffle() : 打乱数据,关于此函数的详细介绍可以参考:zhuanlan.zhihu.com/p/42417456
  • prefetch() :预取数据,加速运行,其详细介绍可以参考我前两篇文章,里面都有讲解。
  • cache() :将数据集缓存到内存当中,加速运行
AUTOTUNE = tf.data.AUTOTUNE

def preprocess_image(image,label):
    return (image/255.0,label)

# 归一化处理
train_ds = train_ds.map(preprocess_image, num_parallel_calls=AUTOTUNE)
val_ds   = val_ds.map(preprocess_image, num_parallel_calls=AUTOTUNE)

train_ds = train_ds.cache().shuffle(1000).prefetch(buffer_size=AUTOTUNE)
val_ds   = val_ds.cache().prefetch(buffer_size=AUTOTUNE)

3. 可视化数据

plt.figure(figsize=(15, 10))  # 图形的宽为15高为10

for images, labels in train_ds.take(1):
    for i in range(8):

        ax = plt.subplot(5, 8, i + 1) 
        plt.imshow(images[i])
        plt.title(class_names[labels[i]])

        plt.axis("off")

t8_catdog_13_1.png

三、 构建VGG-16网络模型

VGG优缺点分析:

  • VGG优点

VGG的结构非常简洁,整个网络都使用了同样大小的卷积核尺寸(3x3)和最大池化尺寸(2x2)。

  • VGG缺点

1)训练时间过长,调参难度大。2)需要的存储容量大,不利于部署。例如存储VGG-16权重值文件的大小为500多MB,不利于安装到嵌入式系统中。

结构说明:

  • 13个卷积层(Convolutional Layer),分别用blockX_convX表示
  • 3个全连接层(Fully connected Layer),分别用fcX与predictions表示
  • 5个池化层(Pool layer),分别用blockX_pool表示

VGG-16包含了16个隐藏层(13个卷积层和3个全连接层),故称为VGG-16

from tensorflow.keras import layers, models, Input
from tensorflow.keras.models import Model
from tensorflow.keras.layers import Conv2D, MaxPooling2D, Dense, Flatten, Dropout

def VGG16(nb_classes, input_shape):
    input_tensor = Input(shape=input_shape)
    # 1st block
    x = Conv2D(64, (3,3), activation='relu', padding='same',name='block1_conv1')(input_tensor)
    x = Conv2D(64, (3,3), activation='relu', padding='same',name='block1_conv2')(x)
    x = MaxPooling2D((2,2), strides=(2,2), name = 'block1_pool')(x)
    # 2nd block
    x = Conv2D(128, (3,3), activation='relu', padding='same',name='block2_conv1')(x)
    x = Conv2D(128, (3,3), activation='relu', padding='same',name='block2_conv2')(x)
    x = MaxPooling2D((2,2), strides=(2,2), name = 'block2_pool')(x)
    # 3rd block
    x = Conv2D(256, (3,3), activation='relu', padding='same',name='block3_conv1')(x)
    x = Conv2D(256, (3,3), activation='relu', padding='same',name='block3_conv2')(x)
    x = Conv2D(256, (3,3), activation='relu', padding='same',name='block3_conv3')(x)
    x = MaxPooling2D((2,2), strides=(2,2), name = 'block3_pool')(x)
    # 4th block
    x = Conv2D(512, (3,3), activation='relu', padding='same',name='block4_conv1')(x)
    x = Conv2D(512, (3,3), activation='relu', padding='same',name='block4_conv2')(x)
    x = Conv2D(512, (3,3), activation='relu', padding='same',name='block4_conv3')(x)
    x = MaxPooling2D((2,2), strides=(2,2), name = 'block4_pool')(x)
    # 5th block
    x = Conv2D(512, (3,3), activation='relu', padding='same',name='block5_conv1')(x)
    x = Conv2D(512, (3,3), activation='relu', padding='same',name='block5_conv2')(x)
    x = Conv2D(512, (3,3), activation='relu', padding='same',name='block5_conv3')(x)
    x = MaxPooling2D((2,2), strides=(2,2), name = 'block5_pool')(x)
    # full connection
    x = Flatten()(x)
    x = Dense(4096, activation='relu',  name='fc1')(x)
    x = Dense(4096, activation='relu', name='fc2')(x)
    output_tensor = Dense(nb_classes, activation='softmax', name='predictions')(x)

    model = Model(input_tensor, output_tensor)
    return model

model=VGG16(1000, (img_width, img_height, 3))
model.summary()
Model: "functional_1"
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┓
┃ Layer (type)                     Output Shape                  Param # ┃
┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━┩
│ input_layer_1 (InputLayer)      │ (None, 224, 224, 3)    │             0 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block1_conv1 (Conv2D)           │ (None, 224, 224, 64)   │         1,792 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block1_conv2 (Conv2D)           │ (None, 224, 224, 64)   │        36,928 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block1_pool (MaxPooling2D)      │ (None, 112, 112, 64)   │             0 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block2_conv1 (Conv2D)           │ (None, 112, 112, 128)  │        73,856 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block2_conv2 (Conv2D)           │ (None, 112, 112, 128)  │       147,584 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block2_pool (MaxPooling2D)      │ (None, 56, 56, 128)    │             0 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block3_conv1 (Conv2D)           │ (None, 56, 56, 256)    │       295,168 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block3_conv2 (Conv2D)           │ (None, 56, 56, 256)    │       590,080 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block3_conv3 (Conv2D)           │ (None, 56, 56, 256)    │       590,080 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block3_pool (MaxPooling2D)      │ (None, 28, 28, 256)    │             0 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block4_conv1 (Conv2D)           │ (None, 28, 28, 512)    │     1,180,160 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block4_conv2 (Conv2D)           │ (None, 28, 28, 512)    │     2,359,808 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block4_conv3 (Conv2D)           │ (None, 28, 28, 512)    │     2,359,808 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block4_pool (MaxPooling2D)      │ (None, 14, 14, 512)    │             0 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block5_conv1 (Conv2D)           │ (None, 14, 14, 512)    │     2,359,808 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block5_conv2 (Conv2D)           │ (None, 14, 14, 512)    │     2,359,808 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block5_conv3 (Conv2D)           │ (None, 14, 14, 512)    │     2,359,808 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ block5_pool (MaxPooling2D)      │ (None, 7, 7, 512)      │             0 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ flatten_1 (Flatten)             │ (None, 25088)          │             0 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ fc1 (Dense)                     │ (None, 4096)           │   102,764,544 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ fc2 (Dense)                     │ (None, 4096)           │    16,781,312 │
├─────────────────────────────────┼────────────────────────┼───────────────┤
│ predictions (Dense)             │ (None, 1000)           │     4,097,000 │
└─────────────────────────────────┴────────────────────────┴───────────────┘
 Total params: 138,357,544 (527.79 MB)
 Trainable params: 138,357,544 (527.79 MB)
 Non-trainable params: 0 (0.00 B)

四、 模型编译与训练

在准备对模型进行训练之前,还需要再对其进行一些设置。以下内容是在模型的编译步骤中添加的:

  • 损失函数(loss):用于衡量模型在训练期间的准确率。
  • 优化器(optimizer):决定模型如何根据其看到的数据和自身的损失函数进行更新。
  • 评价函数(metrics):用于监控训练和测试步骤。以下示例使用了准确率,即被正确分类的图像的比率。
model.compile(optimizer='Adam',
              loss     ='sparse_categorical_crossentropy',
              metrics  =['accuracy'])
from tqdm import tqdm
import tensorflow.python.keras.backend as K
#import tensorflow.keras.backend as K

epochs = 10
lr     = 1e-4

# 记录训练数据,方便后面的分析
history_train_loss     = []
history_train_accuracy = []
history_val_loss       = []
history_val_accuracy   = []

for epoch in range(epochs):
    train_total = len(train_ds)
    val_total   = len(val_ds)

    """
    total:预期的迭代数目
    ncols:控制进度条宽度
    mininterval:进度更新最小间隔,以秒为单位(默认值:0.1)
    """
    with tqdm(total=train_total, desc=f'Epoch {epoch + 1}/{epochs}',mininterval=1,ncols=100) as pbar:

        lr = lr*0.92

        K.set_value(model.optimizer.learning_rate, lr)

        for image,label in train_ds:   
            """
            训练模型,简单理解train_on_batch就是:它是比model.fit()更高级的一个用法

            想详细了解 train_on_batch 的同学,
            可以看看我的这篇文章:https://www.yuque.com/mingtian-fkmxf/hv4lcq/ztt4gy
            """
            history = model.train_on_batch(image,label)

            train_loss     = history[0]
            train_accuracy = history[1]

            pbar.set_postfix({"loss": "%.4f"%train_loss,
                              "accuracy":"%.4f"%train_accuracy,
                              "lr": K.get_value(model.optimizer.learning_rate)})
            pbar.update(1)
        history_train_loss.append(train_loss)
        history_train_accuracy.append(train_accuracy)

    print('开始验证!')

    with tqdm(total=val_total, desc=f'Epoch {epoch + 1}/{epochs}',mininterval=0.3,ncols=100) as pbar:

        for image,label in val_ds:      

            history = model.test_on_batch(image,label)

            val_loss     = history[0]
            val_accuracy = history[1]

            pbar.set_postfix({"loss": "%.4f"%val_loss,
                              "accuracy":"%.4f"%val_accuracy})
            pbar.update(1)
        history_val_loss.append(val_loss)
        history_val_accuracy.append(val_accuracy)

    print('结束验证!')
    print("验证loss为:%.4f"%val_loss)
    print("验证准确率为:%.4f"%val_accuracy)
Epoch 1/10:   1%|          | 2/340 [00:01<04:25,  1.27it/s, loss=6.7076, accuracy=0.3333, lr=9.2e-5]
Epoch 1/10:   1%|          | 2/340 [00:02<04:25,  1.27it/s, loss=6.0955, accuracy=0.4688, lr=9.2e-5]
Epoch 1/10: 100%|███████▉| 339/340 [05:02<00:01,  1.03s/it, loss=0.8013, accuracy=0.5554, lr=9.2e-5]2024-10-25 17:11:32.477473: I tensorflow/core/framework/local_rendezvous.cc:404] Local rendezvous is aborting with status: OUT_OF_RANGE: End of sequence
Epoch 1/10: 100%|████████| 340/340 [05:02<00:00,  1.13it/s, loss=0.8013, accuracy=0.5554, lr=9.2e-5]

开始验证!

Epoch 1/10:   4%|▊                     | 3/85 [00:04<01:30,  1.11s/it, loss=0.7974, accuracy=0.5576]
Epoch 1/10:   6%|█▎                    | 5/85 [00:04<00:50,  1.57it/s, loss=0.7960, accuracy=0.5585]
Epoch 1/10: 100%|█████████████████████| 85/85 [00:20<00:00,  4.09it/s, loss=0.7456, accuracy=0.5866]

结束验证!
验证loss为:0.7456
验证准确率为:0.5866

Epoch 2/10: 100%|███████| 340/340 [06:15<00:00,  1.06s/it, loss=0.5481, accuracy=0.7182, lr=8.46e-5]2024-10-25 17:18:08.713738: I tensorflow/core/framework/local_rendezvous.cc:404] Local rendezvous is aborting with status: OUT_OF_RANGE: End of sequence
Epoch 2/10: 100%|███████| 340/340 [06:15<00:00,  1.10s/it, loss=0.5481, accuracy=0.7182, lr=8.46e-5]

开始验证!

Epoch 2/10: 100%|█████████████████████| 85/85 [00:18<00:00,  4.71it/s, loss=0.5062, accuracy=0.7409]

结束验证!
验证loss为:0.5062
验证准确率为:0.7409

Epoch 3/10: 100%|███████| 340/340 [07:21<00:00,  1.30s/it, loss=0.3960, accuracy=0.8035, lr=7.79e-5]

开始验证!

Epoch 3/10: 100%|█████████████████████| 85/85 [00:19<00:00,  4.39it/s, loss=0.3808, accuracy=0.8121]

结束验证!
验证loss为:0.3808
验证准确率为:0.8121

Epoch 4/10: 100%|███████| 340/340 [07:58<00:00,  1.43s/it, loss=0.3168, accuracy=0.8453, lr=7.16e-5]2024-10-25 17:34:06.505774: I tensorflow/core/framework/local_rendezvous.cc:404] Local rendezvous is aborting with status: OUT_OF_RANGE: End of sequence
Epoch 4/10: 100%|███████| 340/340 [07:58<00:00,  1.41s/it, loss=0.3168, accuracy=0.8453, lr=7.16e-5]

开始验证!

Epoch 4/10: 100%|█████████████████████| 85/85 [00:21<00:00,  3.88it/s, loss=0.3087, accuracy=0.8509]

结束验证!
验证loss为:0.3087
验证准确率为:0.8509

Epoch 5/10: 100%|███████| 340/340 [08:55<00:00,  1.57s/it, loss=0.2694, accuracy=0.8714, lr=6.59e-5]
开始验证!

Epoch 5/10: 100%|█████████████████████| 85/85 [00:24<00:00,  3.44it/s, loss=0.2619, accuracy=0.8754]

结束验证!
验证loss为:0.2619
验证准确率为:0.8754

Epoch 6/10: 100%|███████| 340/340 [10:09<00:00,  1.79s/it, loss=0.2315, accuracy=0.8905, lr=6.06e-5]

开始验证!

Epoch 6/10: 100%|█████████████████████| 85/85 [00:25<00:00,  3.35it/s, loss=0.2251, accuracy=0.8937]

结束验证!
验证loss为:0.2251
验证准确率为:0.8937

Epoch 7/10: 100%|███████| 340/340 [10:49<00:00,  1.91s/it, loss=0.2022, accuracy=0.9049, lr=5.58e-5]

开始验证!

Epoch 7/10: 100%|█████████████████████| 85/85 [00:25<00:00,  3.30it/s, loss=0.1971, accuracy=0.9074]

结束验证!
验证loss为:0.1971
验证准确率为:0.9074

Epoch 8/10: 100%|███████| 340/340 [12:02<00:00,  2.26s/it, loss=0.1803, accuracy=0.9158, lr=5.13e-5]2024-10-25 18:17:40.812619: I tensorflow/core/framework/local_rendezvous.cc:404] Local rendezvous is aborting with status: OUT_OF_RANGE: End of sequence
Epoch 8/10: 100%|███████| 340/340 [12:02<00:00,  2.13s/it, loss=0.1803, accuracy=0.9158, lr=5.13e-5]

开始验证!

Epoch 8/10: 100%|█████████████████████| 85/85 [00:30<00:00,  2.83it/s, loss=0.1783, accuracy=0.9171]

结束验证!
验证loss为:0.1783
验证准确率为:0.9171

Epoch 9/10: 100%|███████| 340/340 [12:53<00:00,  2.28s/it, loss=0.1648, accuracy=0.9240, lr=4.72e-5]

开始验证!

Epoch 9/10: 100%|█████████████████████| 85/85 [00:29<00:00,  2.85it/s, loss=0.1614, accuracy=0.9255]

结束验证!
验证loss为:0.1614
验证准确率为:0.9255

Epoch 10/10: 100%|██████| 340/340 [13:48<00:00,  2.44s/it, loss=0.1500, accuracy=0.9310, lr=4.34e-5]

开始验证!

Epoch 10/10: 100%|████████████████████| 85/85 [00:30<00:00,  2.78it/s, loss=0.1474, accuracy=0.9322]

结束验证!
验证loss为:0.1474
验证准确率为:0.9322
# 这是我们之前的训练方法。
# history = model.fit(
#     train_ds,
#     validation_data=val_ds,
#     epochs=epochs
# )

五、 模型评估

epochs_range = range(epochs)

plt.figure(figsize=(12, 4))
plt.subplot(1, 2, 1)

plt.plot(epochs_range, history_train_accuracy, label='Training Accuracy')
plt.plot(epochs_range, history_val_accuracy, label='Validation Accuracy')
plt.legend(loc='lower right')
plt.title('Training and Validation Accuracy')

plt.subplot(1, 2, 2)
plt.plot(epochs_range, history_train_loss, label='Training Loss')
plt.plot(epochs_range, history_val_loss, label='Validation Loss')
plt.legend(loc='upper right')
plt.title('Training and Validation Loss')
plt.show()

t8_catdog_21_1.png

六、 预测

import numpy as np

# 采用加载的模型(new_model)来看预测结果
plt.figure(figsize=(18, 3))  # 图形的宽为18高为5
plt.suptitle("预测结果展示")

for images, labels in val_ds.take(1):
    for i in range(8):
        ax = plt.subplot(1,8, i + 1)  

        # 显示图片
        plt.imshow(images[i].numpy())

        # 需要给图片增加一个维度
        img_array = tf.expand_dims(images[i], 0) 

        # 使用模型预测图片中的人物
        predictions = model.predict(img_array)
        plt.title(class_names[np.argmax(predictions)])

        plt.axis("off")
1/1 ━━━━━━━━━━━━━━━━━━━━ 104s 104s/step
1/1 ━━━━━━━━━━━━━━━━━━━━ 0s 68ms/step
1/1 ━━━━━━━━━━━━━━━━━━━━ 0s 45ms/step
1/1 ━━━━━━━━━━━━━━━━━━━━ 0s 56ms/step
1/1 ━━━━━━━━━━━━━━━━━━━━ 0s 60ms/step
1/1 ━━━━━━━━━━━━━━━━━━━━ 0s 67ms/step
1/1 ━━━━━━━━━━━━━━━━━━━━ 0s 95ms/step
1/1 ━━━━━━━━━━━━━━━━━━━━ 0s 38ms/step

t8_catdog_23_3.png

七、 总结

  • 在版本TF2.17.0中,需要用 "import tensorflow.python.keras.backend as K" 替换 "import tensorflow.keras.backend as K"
  • model.optimizer.learning_rate 替换 model.optimizer.lr
  • tqdm的进度条显示非常直观,且引入tqdm非常方便。
  • 整个模型训练耗时3小时,平均GPU内存消耗8.6Gb (RTX3090).