AttributeError: module 'tensorflow._api.v2.train.experimental' has no attribute 'enable_mixed_precision_graph_rewrite'

针对AttributeError: module 'tensorflow._api.v2.train.experimental' has no attribute 'enable_mixed_precision_graph_rewrite'的问题，这是因为在TensorFlow 2.4及以上版本中，enable_mixed_precision_graph_rewrite已被弃用。如果您需要使用混合精度训练，请使用tf.keras.mixed_precision.experimental.LossScaleOptimizer。以下是一个使用LossScaleOptimizer的例子：

import tensorflow as tf
from tensorflow.keras import layers
from tensorflow.keras.mixed_precision import experimental as mixed_precision

# 设置混合精度
policy = mixed_precision.Policy('mixed_float16')
mixed_precision.set_policy(policy)

# 构建模型
model = tf.keras.Sequential([
    layers.Dense(16, activation='relu', input_shape=(10,)),
    layers.Dense(1, activation='sigmoid')
])

# 编译模型
optimizer = tf.keras.optimizers.Adam()
optimizer = mixed_precision.LossScaleOptimizer(optimizer)
model.compile(loss='binary_crossentropy', optimizer=optimizer)

# 训练模型
model.fit(x_train, y_train, epochs=10, batch_size=32)