请将此代码修改为tensorflow2.7，cuda11.2版本的代码 import tensorflow as tf from tensorflow import keras from tensorflow.keras.datasets import mnist from tensorflow.keras.models import Sequential from tensorflow.keras.layers import Conv2D, MaxPooling2D, Flatten, Dense, ReLU from tensorflow.keras.utils import to_categorical # 加载MNIST数据集 (x_train, y_train), (x_test, y_test) = mnist.load_data() # 数据预处理 x_train = x_train.astype("float32") / 255.0 x_test = x_test.astype("float32") / 255.0 x_train = tf.expand_dims(x_train, axis=3) x_test = tf.expand_dims(x_test, axis=3) y_train = to_categorical(y_train, num_classes=10) y_test = to_categorical(y_test, num_classes=10) # 构建LeNet-5模型 model = Sequential([ Conv2D(6, kernel_size=3, strides=1), MaxPooling2D(pool_size=2, strides=2), ReLU(), Conv2D(16, kernel_size=3, strides=1), MaxPooling2D(pool_size=2, strides=2), ReLU(), Flatten(), Dense(units=120, activation='relu'), Dense(units=84, activation='relu'), Dense(units=10, activation='softmax') ]) # 编译模型 model.compile(optimizer='adam', loss='categorical_crossentropy', metrics=['accuracy']) # 训练模型 model.fit(x_train, y_train, batch_size=128, epochs=30, validation_data=(x_test, y_test)) # 在测试集上输出精度 test_loss, test_acc = model.evaluate(x_test, y_test) print('Test accuracy:', test_acc)

这是一个类似的 TensorFlow 2.7 和 CUDA 11.2 版本的代码示例：

import tensorflow as tf
from tensorflow import keras
from tensorflow.keras.datasets import mnist
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Conv2D, MaxPooling2D, Flatten, Dense, ReLU
from tensorflow.keras.utils import to_categorical

# Set GPU device
gpus = tf.config.experimental.list_physical_devices('GPU')
if gpus:
    try:
        tf.config.experimental.set_visible_devices(gpus[0], 'GPU')
        tf.config.experimental.set_memory_growth(gpus[0], True)
        print("Using GPU:", tf.test.gpu_device_name())
    except RuntimeError as e:
        print(e)

# Load MNIST dataset
(x_train, y_train), (x_test, y_test) = mnist.load_data()

# Preprocess data
x_train = x_train.astype("float32") / 255.0
x_test = x_test.astype("float32") / 255.0
x_train = tf.expand_dims(x_train, axis=3)
x_test = tf.expand_dims(x_test, axis=3)
y_train = to_categorical(y_train, num_classes=10)
y_test = to_categorical(y_test, num_classes=10)

# Define LeNet-5 model
model = Sequential([
    Conv2D(6, kernel_size=3, strides=1),
    MaxPooling2D(pool_size=2, strides=2),
    ReLU(),
    Conv2D(16, kernel_size=3, strides=1),
    MaxPooling2D(pool_size=2, strides=2),
    ReLU(),
    Flatten(),
    Dense(units=120, activation='relu'),
    Dense(units=84, activation='relu'),
    Dense(units=10, activation='softmax')
])

# Compile model
model.compile(optimizer='adam',
              loss='categorical_crossentropy',
              metrics=['accuracy'])

# Train model
model.fit(x_train, y_train, batch_size=128, epochs=30, validation_data=(x_test, y_test))

# Evaluate model on test set
test_loss, test_acc = model.evaluate(x_test, y_test)
print('Test accuracy:', test_acc)

这个代码实现了一个 LeNet-5 模型，用于识别 MNIST 手写数字。它使用了 TensorFlow 2.7 和 CUDA 11.2 版本，并且在 GPU 上训练模型。在代码中，我们首先检查是否有可用的 GPU 设备，并设置 TensorFlow 只使用第一个 GPU 设备。然后，我们加载 MNIST 数据集并对其进行预处理。接下来，我们定义了一个包含两个卷积层和三个全连接层的 LeNet-5 模型，并使用 Adam 优化器和交叉熵损失函数编译了模型。最后，我们在训练集上训练模型，并在测试集上评估模型的准确性。