周总结 4.20-4.27

彩色图片分类 

一、前期工作
1. 设置GPU
如果使用的是CPU可以忽略这步

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
import tensorflow as tf
from tensorflow.keras import datasets, layers, models
import matplotlib.pyplot as plt

(train_images, train_labels), (test_images, test_labels) = datasets.cifar10.load_data()

3. 归一化
# 将像素的值标准化至0到1的区间内。
train_images, test_images = train_images / 255.0, test_images / 255.0

train_images.shape,test_images.shape,train_labels.shape,test_labels.shape

((50000, 32, 32, 3), (10000, 32, 32, 3), (50000, 1), (10000, 1))

4. 可视化
class_names = ['airplane', 'automobile', 'bird', 'cat', 'deer','dog', 'frog', 'horse', 'ship', 'truck']

plt.figure(figsize=(20,10))
for i in range(20):
plt.subplot(5,10,i+1)
plt.xticks([])
plt.yticks([])
plt.grid(False)
plt.imshow(train_images[i], cmap=plt.cm.binary)
plt.xlabel(class_names[train_labels[i][0]])
plt.show()

二、构建CNN网络
model = models.Sequential([
layers.Conv2D(32, (3, 3), activation='relu', input_shape=(32, 32, 3)), #卷积层1，卷积核3*3
layers.MaxPooling2D((2, 2)), #池化层1，2*2采样
layers.Conv2D(64, (3, 3), activation='relu'), #卷积层2，卷积核3*3
layers.MaxPooling2D((2, 2)), #池化层2，2*2采样
layers.Conv2D(64, (3, 3), activation='relu'), #卷积层3，卷积核3*3

layers.Flatten(), #Flatten层，连接卷积层与全连接层
layers.Dense(64, activation='relu'), #全连接层，特征进一步提取
layers.Dense(10) #输出层，输出预期结果
])

model.summary() # 打印网络结构

Model: "sequential"
_________________________________________________________________
Layer (type) Output Shape Param #
=================================================================
conv2d (Conv2D) (None, 30, 30, 32) 896
_________________________________________________________________
max_pooling2d (MaxPooling2D) (None, 15, 15, 32) 0
_________________________________________________________________
conv2d_1 (Conv2D) (None, 13, 13, 64) 18496
_________________________________________________________________
max_pooling2d_1 (MaxPooling2 (None, 6, 6, 64) 0
_________________________________________________________________
conv2d_2 (Conv2D) (None, 4, 4, 64) 36928
_________________________________________________________________
flatten (Flatten) (None, 1024) 0
_________________________________________________________________
dense (Dense) (None, 64) 65600
_________________________________________________________________
dense_1 (Dense) (None, 10) 650
=================================================================
Total params: 122,570
Trainable params: 122,570
Non-trainable params: 0
_________________________________________________________________

三、编译
model.compile(optimizer='adam',
loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True),
metrics=['accuracy'])

四、训练模型
history = model.fit(train_images, train_labels, epochs=10,
validation_data=(test_images, test_labels))

Epoch 1/10
1563/1563 [==============================] - 9s 4ms/step - loss: 1.7862 - accuracy: 0.3390 - val_loss: 1.2697 - val_accuracy: 0.5406
Epoch 2/10
1563/1563 [==============================] - 5s 3ms/step - loss: 1.2270 - accuracy: 0.5595 - val_loss: 1.0731 - val_accuracy: 0.6167
Epoch 3/10
1563/1563 [==============================] - 5s 3ms/step - loss: 1.0355 - accuracy: 0.6337 - val_loss: 0.9678 - val_accuracy: 0.6610
Epoch 4/10
1563/1563 [==============================] - 5s 3ms/step - loss: 0.9221 - accuracy: 0.6727 - val_loss: 0.9589 - val_accuracy: 0.6648
Epoch 5/10
1563/1563 [==============================] - 5s 3ms/step - loss: 0.8474 - accuracy: 0.7022 - val_loss: 0.8962 - val_accuracy: 0.6853
Epoch 6/10
1563/1563 [==============================] - 5s 3ms/step - loss: 0.7814 - accuracy: 0.7292 - val_loss: 0.9124 - val_accuracy: 0.6873
Epoch 7/10
1563/1563 [==============================] - 5s 3ms/step - loss: 0.7398 - accuracy: 0.7398 - val_loss: 0.8924 - val_accuracy: 0.6929
Epoch 8/10
1563/1563 [==============================] - 5s 3ms/step - loss: 0.7008 - accuracy: 0.7542 - val_loss: 0.9809 - val_accuracy: 0.6854
Epoch 9/10
1563/1563 [==============================] - 5s 3ms/step - loss: 0.6474 - accuracy: 0.7732 - val_loss: 0.8549 - val_accuracy: 0.7137
Epoch 10/10
1563/1563 [==============================] - 5s 3ms/step - loss: 0.6041 - accuracy: 0.7889 - val_loss: 0.8909 - val_accuracy: 0.7046

五、预测
通过模型进行预测得到的是每一个类别的概率，数字越大该图片为该类别的可能性越大

plt.imshow(test_images[1])

import numpy as np

pre = model.predict(test_images)
print(class_names[np.argmax(pre[1])])

ship

六、模型评估
import matplotlib.pyplot as plt

plt.plot(history.history['accuracy'], label='accuracy')
plt.plot(history.history['val_accuracy'], label = 'val_accuracy')
plt.xlabel('Epoch')
plt.ylabel('Accuracy')
plt.ylim([0.5, 1])
plt.legend(loc='lower right')
plt.show()

test_loss, test_acc = model.evaluate(test_images, test_labels, verbose=2)

313/313 - 0s - loss: 0.8909 - accuracy: 0.7046

print(test_acc)

0.7045999765396118