- 🍨 本文为🔗365天深度学习训练营 中的学习记录博客
- 🍖 原作者:K同学啊
文章目录
- 一、前期工作
- 1.设置GPU(如果使用的是CPU可以忽略这步)
- 2. 导入数据
- 3. 查看数据
- 二、数据预处理
- 1、加载数据
- 2、数据可视化
- 3、再次检查数据
- 4、配置数据集
- 三、构建CNN网络
- 四、编译
- 五、训练模型
- 六、模型评估
- 1. Loss与Accuracy图
- 2.指定图片进行预测
- 七、优化
- 1、使用`model.evaluate`使用测试集评估模型
- 2、网络结构优化
- 3、 Loss与Accuracy图
- 4、使用`model.evaluate`评估优化后的模型
- 八、总结
电脑环境:
语言环境:Python 3.8.0
编译器:Jupyter Notebook
深度学习环境:tensorflow 2.15.0
一、前期工作
1.设置GPU(如果使用的是CPU可以忽略这步)
from tensorflow import keras
from keras import layers, models
import os, PIL, pathlib
import matplotlib.pyplot as plt
import tensorflow as tf
gpus = tf.config.list_physical_devices("GPU")
if gpus:
gpu0 = gpus[0] #如果有多个GPU,仅使用第0个GPU
tf.config.experimental.set_memory_growth(gpu0, True) #设置GPU显存用量按需使用
tf.config.set_visible_devices([gpu0],"GPU")
2. 导入数据
data_dir = "./data/"
data_dir = pathlib.Path(data_dir)
3. 查看数据
image_count = len(list(data_dir.glob('*/*.jpg')))
print("图片总数为:",image_count)
输出:图片总数为: 2142
打开一张图片:
Monkeypox = list(data_dir.glob('Monkeypox/*.jpg'))
PIL.Image.open(str(Monkeypox[1]))
二、数据预处理
1、加载数据
使用image_dataset_from_directory方法将磁盘中的数据加载到tf.data.Dataset中。
测试集与验证集的关系:
- 验证集并没有参与训练过程梯度下降过程的,狭义上来讲是没有参与模型的参数训练更新的。
- 但是广义上来讲,验证集存在的意义确实参与了一个“人工调参”的过程,我们根据每一个epoch训练之后模型在valid data上的表现来决定是否需要训练进行early stop,或者根据这个过程模型的性能变化来调整模型的超参数,如学习率,batch_size等等。
- 因此,我们也可以认为,验证集也参与了训练,但是并没有使得模型去overfit验证集。
batch_size = 32
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=123,
image_size=(img_height, img_width),
batch_size=batch_size)
val_ds = tf.keras.preprocessing.image_dataset_from_directory(
data_dir,
validation_split=0.2,
subset="validation",
seed=123,
image_size=(img_height, img_width),
batch_size=batch_size)
我们可以通过class_names输出数据集的标签。标签将按字母顺序对应于目录名称。
class_names = train_ds.class_names
print(class_names)
输出:
[‘Monkeypox’, ‘Others’]
2、数据可视化
plt.figure(figsize=(20, 10))
for images, labels in train_ds.take(1):
for i in range(20):
ax = plt.subplot(5, 10, i + 1)
plt.imshow(images[i].numpy().astype("uint8"))
plt.title(class_names[labels[i]])
plt.axis("off")
3、再次检查数据
for image_batch, labels_batch in train_ds:
print(image_batch.shape)
print(labels_batch.shape)
break
输出:
(32, 224, 224, 3)
(32,)
4、配置数据集
AUTOTUNE = tf.data.AUTOTUNE
train_ds = train_ds.cache().shuffle(1000).prefetch(buffer_size=AUTOTUNE)
val_ds = val_ds.cache().prefetch(buffer_size=AUTOTUNE)
三、构建CNN网络
num_classes = 2
"""
关于卷积核的计算不懂的可以参考文章:https://blog.csdn.net/qq_38251616/article/details/114278995
layers.Dropout(0.4) 作用是防止过拟合,提高模型的泛化能力。
在上一篇文章花朵识别中,训练准确率与验证准确率相差巨大就是由于模型过拟合导致的
关于Dropout层的更多介绍可以参考文章:https://mtyjkh.blog.csdn.net/article/details/115826689
"""
model = models.Sequential([
layers.experimental.preprocessing.Rescaling(1./255, input_shape=(img_height, img_width, 3)), # 归一化
layers.Conv2D(16, (3, 3), activation='relu', input_shape=(img_height, img_width, 3)), # 卷积层1,卷积核3*3
layers.AveragePooling2D((2, 2)), # 池化层1,2*2采样
layers.Conv2D(32, (3, 3), activation='relu'), # 卷积层2,卷积核3*3
layers.AveragePooling2D((2, 2)), # 池化层2,2*2采样
layers.Dropout(0.3),
layers.Conv2D(64, (3, 3), activation='relu'), # 卷积层3,卷积核3*3
layers.Dropout(0.3),
layers.Flatten(), # Flatten层,连接卷积层与全连接层
layers.Dense(128, activation='relu'), # 全连接层,特征进一步提取
layers.Dense(num_classes) # 输出层,输出预期结果
])
model.summary() # 打印网络结构
四、编译
# 设置优化器
opt = tf.keras.optimizers.Adam(learning_rate=1e-4)
model.compile(optimizer=opt,
loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True),
metrics=['accuracy'])
五、训练模型
关于ModelCheckpoint的详细介绍可参考文章ModelCheckpoint 讲解【TensorFlow2入门手册】
from tensorflow.keras.callbacks import ModelCheckpoint
epochs = 50
checkpointer = ModelCheckpoint('best_model.h5', # 保存最好模型的路径
monitor='val_accuracy', # 需要监视的指标
verbose=1, # 信息展示模式,0/1
save_best_only=True, # 当设置为True时,监测指标有改进时才会保存当前的模型
save_weights_only=True) # 当设置为True时,则只保存模型权重,否则将保存整个模型(模型结构,配置信息等)
history = model.fit(train_ds,
validation_data=val_ds,
epochs=epochs,
callbacks=[checkpointer])
输出:
Epoch 1/50
53/54 [============================>.] - ETA: 0s - loss: 0.7034 - accuracy: 0.5612
Epoch 1: val_accuracy improved from -inf to 0.58879, saving model to /content/drive/MyDrive/app/T4/best_model.h5
54/54 [==============================] - 280s 976ms/step - loss: 0.7029 - accuracy: 0.5607 - val_loss: 0.6588 - val_accuracy: 0.5888
.................................
Epoch 47/50
53/54 [============================>.] - ETA: 0s - loss: 0.0545 - accuracy: 0.9875
Epoch 47: val_accuracy did not improve from 0.88318
54/54 [==============================] - 2s 45ms/step - loss: 0.0549 - accuracy: 0.9872 - val_loss: 0.4760 - val_accuracy: 0.8762
Epoch 48/50
53/54 [============================>.] - ETA: 0s - loss: 0.0525 - accuracy: 0.9857
Epoch 48: val_accuracy did not improve from 0.88318
54/54 [==============================] - 3s 48ms/step - loss: 0.0526 - accuracy: 0.9860 - val_loss: 0.4829 - val_accuracy: 0.8808
Epoch 49/50
54/54 [==============================] - ETA: 0s - loss: 0.0606 - accuracy: 0.9802
Epoch 49: val_accuracy improved from 0.88318 to 0.88551, saving model to /content/drive/MyDrive/app/T4/best_model.h5
54/54 [==============================] - 4s 76ms/step - loss: 0.0606 - accuracy: 0.9802 - val_loss: 0.5093 - val_accuracy: 0.8855
Epoch 50/50
53/54 [============================>.] - ETA: 0s - loss: 0.0614 - accuracy: 0.9786
Epoch 50: val_accuracy did not improve from 0.88551
54/54 [==============================] - 3s 51ms/step - loss: 0.0615 - accuracy: 0.9784 - val_loss: 0.4773 - val_accuracy: 0.8762
六、模型评估
1. Loss与Accuracy图
acc = history.history['accuracy']
val_acc = history.history['val_accuracy']
loss = history.history['loss']
val_loss = history.history['val_loss']
epochs_range = range(epochs)
plt.figure(figsize=(12, 4))
plt.subplot(1, 2, 1)
plt.plot(epochs_range, acc, label='Training Accuracy')
plt.plot(epochs_range, val_acc, label='Validation Accuracy')
plt.legend(loc='lower right')
plt.title('Training and Validation Accuracy')
plt.subplot(1, 2, 2)
plt.plot(epochs_range, loss, label='Training Loss')
plt.plot(epochs_range, val_loss, label='Validation Loss')
plt.legend(loc='upper right')
plt.title('Training and Validation Loss')
plt.show()
2.指定图片进行预测
# 加载效果最好的模型权重
model.load_weights('best_model.h5')
from PIL import Image
import numpy as np
# img = Image.open("./45-data/Monkeypox/M06_01_04.jpg") #这里选择你需要预测的图片
img = Image.open("./45-data/Others/NM01_01_00.jpg") #这里选择你需要预测的图片
image = tf.image.resize(img, [img_height, img_width])
img_array = tf.expand_dims(image, 0)
predictions = model.predict(img_array) # 这里选用你已经训练好的模型
print("预测结果为:",class_names[np.argmax(predictions)])
输出:
1/1 [==============================] - 0s 19ms/step
预测结果为: Others
预测正确。
七、优化
1、使用model.evaluate
使用测试集评估模型
test_loss, test_acc = model.evaluate(val_ds, verbose=1) # verbose=0不显示进度条,1显示进度条
print('Test loss:', test_loss)
print('Test accuracy:', test_acc)
输出:
14/14 [==============================] - 0s 16ms/step - loss: 0.5093 - accuracy: 0.8855
Test loss: 0.5093046426773071
Test accuracy: 0.8855140209197998
在上边Loss与Accuracy图中可以看出,模型存在过拟合的问题,出现过拟合的问题解决办法有减小网络的大小、添加正则化项、添加dropout层等。
2、网络结构优化
经过多次训练和优化,最终效果最好的网络结构如下:包括5个卷积层,5个池化层,1个dropout层。
num_classes = 2
model = models.Sequential([
layers.experimental.preprocessing.Rescaling(1./255, input_shape=(img_height, img_width, 3)),
layers.Conv2D(16, (3, 3), activation='relu', input_shape=(img_height, img_width, 3)), # 卷积层1
layers.AveragePooling2D((2, 2)), # 池化层1
layers.Conv2D(32, (3, 3), activation='relu'), # 卷积层2
layers.AveragePooling2D((2, 2)), # 池化层2
layers.Conv2D(32, (3, 3), activation='relu'), # 卷积层3
layers.AveragePooling2D((2, 2)), # 池化层3
layers.Conv2D(32, (3, 3), activation='relu'), # 卷积层4
layers.AveragePooling2D((2, 2)), # 池化层4
layers.Conv2D(64, (3, 3), activation='relu'), # 卷积层5
layers.AveragePooling2D((2, 2)), # 池化层5
layers.Dropout(0.4),
layers.Flatten(),
layers.Dense(128, activation='relu'),
layers.Dense(num_classes)
])
训练输出结果:
Epoch 1/50
54/54 [==============================] - ETA: 0s - loss: 0.6823 - accuracy: 0.5443
Epoch 1: val_accuracy improved from -inf to 0.56308, saving model to /content/drive/MyDrive/app/T4/best_model2.h5
54/54 [==============================] - 5s 52ms/step - loss: 0.6823 - accuracy: 0.5443 - val_loss: 0.6771 - val_accuracy: 0.5631
。。。。。。。。。。。。。。。。。。。。。。。。。。。。
Epoch 47/50
53/54 [============================>.] - ETA: 0s - loss: 0.3012 - accuracy: 0.8757
Epoch 47: val_accuracy improved from 0.85981 to 0.87383, saving model to /content/drive/MyDrive/app/T4/best_model2.h5
54/54 [==============================] - 3s 52ms/step - loss: 0.3042 - accuracy: 0.8734 - val_loss: 0.3395 - val_accuracy: 0.8738
Epoch 48/50
53/54 [============================>.] - ETA: 0s - loss: 0.3027 - accuracy: 0.8829
Epoch 48: val_accuracy did not improve from 0.87383
54/54 [==============================] - 2s 38ms/step - loss: 0.3056 - accuracy: 0.8810 - val_loss: 0.3355 - val_accuracy: 0.8738
Epoch 49/50
53/54 [============================>.] - ETA: 0s - loss: 0.3036 - accuracy: 0.8805
Epoch 49: val_accuracy did not improve from 0.87383
54/54 [==============================] - 2s 38ms/step - loss: 0.3021 - accuracy: 0.8816 - val_loss: 0.3387 - val_accuracy: 0.8621
Epoch 50/50
53/54 [============================>.] - ETA: 0s - loss: 0.2950 - accuracy: 0.8912
Epoch 50: val_accuracy improved from 0.87383 to 0.89019, saving model to /content/drive/MyDrive/app/T4/best_model2.h5
54/54 [==============================] - 2s 39ms/step - loss: 0.2945 - accuracy: 0.8909 - val_loss: 0.3172 - val_accuracy: 0.8902
3、 Loss与Accuracy图
从图中可以看出模型过拟合的影响大大减小,我没有在网络中增加正则化项,模型还有提升的空间。
4、使用model.evaluate
评估优化后的模型
test_loss, test_acc = model.evaluate(val_ds, verbose=1) # verbose=0不显示进度条,1显示进度条
print('Test loss:', test_loss)
print('Test accuracy:', test_acc)
输出:
14/14 [==============================] - 0s 13ms/step - loss: 0.3172 - accuracy: 0.8902
Test loss: 0.31724825501441956
Test accuracy: 0.8901869058609009
测试集的loss大大减小,且acc提高了。
八、总结
对于神经网络学习图片特征过程中,过拟合现象很容易发生,耐心调参即可对模型进行优化。