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import os
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import tensorflow as tf
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from tensorflow.keras.models import Sequential
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from tensorflow.keras.layers import Dense, Dropout, Conv2D, MaxPooling2D, Flatten
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from tensorflow.keras.optimizers import Adam
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from tensorflow.keras.callbacks import EarlyStopping, ModelCheckpoint
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import tensorflow as tf
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print(tf.__version__)
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# 导入数据
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mnist = tf.keras.datasets.mnist
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(train_data, train_target), (test_data, test_target) = mnist.load_data()
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# 改变数据维度
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# 改变数据维度
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train_data = train_data.reshape(-1, 28, 28, 1)
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test_data = test_data.reshape(-1, 28, 28, 1)
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# 注：在TensorFlow中，在做卷积的时候需要把数据变成4维的格式
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# 这4个维度分别是：数据数量，图片高度，图片宽度，图片通道数
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# 归一化（有助于提升训练速度）
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train_data = train_data / 255.0
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test_data = test_data / 255.0
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# 独热编码
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train_target = tf.keras.utils.to_categorical(train_target, num_classes=10)
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test_target = tf.keras.utils.to_categorical(test_target, num_classes=10) # 10种结果
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# 配置早停
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early_stopping = EarlyStopping(monitor='val_loss', patience=3, verbose=1, restore_best_weights=True)
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# 配置GPU加速
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strategy = tf.distribute.MirroredStrategy()
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print('Number of devices: {}'.format(strategy.num_replicas_in_sync))
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with strategy.scope():
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# 构建更复杂的模型
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model = tf.keras.Sequential([
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Conv2D(32, (3, 3), activation='relu', input_shape=(28, 28, 1), padding = 'same'),
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MaxPooling2D((2, 2), padding = 'same'),
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Conv2D(64, (3, 3), activation='relu', padding = 'same'),
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MaxPooling2D((2, 2), padding = 'same'),
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Flatten(),
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Dense(1024, activation='relu'),
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Dropout(0.5),
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Dense(10, activation='softmax')
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])
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# 编译模型
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optimizer = tf.keras.optimizers.Adam(learning_rate=0.001)
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model.compile(optimizer=optimizer, loss='categorical_crossentropy', metrics=['accuracy'])
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# # 配置模型检查点，保存最优模型
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# checkpoint_path = "./model/number_model.h5"
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# model_checkpoint = ModelCheckpoint(checkpoint_path, monitor='val_loss',
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# save_best_only=True, save_weights_only=False, verbose=1)
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# 训练模型
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model.fit(train_data, train_target, epochs=5, validation_data=(test_data, test_target), callbacks=[early_stopping])
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# 保存模型为 .h5 文件
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model.save("./model/number_model.h5", save_format='h5')
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