with tf.compat.v1.Session(graph=g) as sess:

这是一个使用 TensorFlow 库创建的会话对象，其中 g 是一个 TensorFlow 计算图。在这个会话中，可以运行计算图中的操作，计算图中的变量也可以在会话中被更新。在 TensorFlow 2.x 版本中，不再需要使用 Session 对象，而是直接使用 Eager Execution 模式。

相关问题

import tensorflow as tf ## create a graph g = tf.Graph() # 此处替换掉placeholder，是因为 "placeholder" 不再是 TensorFlow 的一部分了。在 TensorFlow 2.0 中， # 它已被弃用，并被 tf.compat.v1.placeholder 替换。在新版本中建议使用tf.function和tf.Tensor来完成相同的功能. with g.as_default(): # x = tf.placeholder(dtype=tf.float32, # shape=(None), name='x') x = tf.Tensor(dtype=tf.float32, shape=(None), name='x') w = tf.Variable(2.0, name='weight') b = tf.Variable(0.7, name='bias') z = w*x + b init = tf.global_variables_initializer() ## create a session and pass in graph g with tf.Session(graph=g) as sess: ## initialize w and b: sess.run(init) ## evaluate z: for t in [1.0, 0.6, -1.8]: print('x=%4.1f --> z=%4.1f'%( t, sess.run(z, feed_dict={x:t})))

This code creates a TensorFlow graph that defines a linear regression model and evaluates it for different values of the input variable `x`.

The graph is defined using the `tf.Graph()` context manager, which creates a new graph and sets it as the default graph for all subsequent operations inside the context.

Inside the graph, a TensorFlow `Tensor` object is created to represent the input variable `x`. Note that the `tf.placeholder()` function is replaced with `tf.Tensor()` because `tf.placeholder()` is deprecated in TensorFlow 2.0.

Two TensorFlow `Variable` objects are also created to represent the model parameters `w` and `b`, which are initialized to 2.0 and 0.7, respectively.

Finally, a TensorFlow operation is defined to compute the output `z` of the linear regression model, which is simply the product of `w` and `x`, plus `b`.

A TensorFlow `Session` object is created to run the graph. The `global_variables_initializer()` function is used to initialize the variables `w` and `b`. Then, the `z` operation is evaluated for three different values of `x` (1.0, 0.6, and -1.8), and the results are printed to the console.

import time import tensorflow.compat.v1 as tf tf.disable_v2_behavior() from tensorflow.examples.tutorials.mnist import input_data import mnist_inference import mnist_train tf.compat.v1.reset_default_graph() EVAL_INTERVAL_SECS = 10 def evaluate(mnist): with tf.Graph().as_default() as g: #定义输入与输出的格式 x = tf.compat.v1.placeholder(tf.float32, [None, mnist_inference.INPUT_NODE], name='x-input') y_ = tf.compat.v1.placeholder(tf.float32, [None, mnist_inference.OUTPUT_NODE], name='y-input') validate_feed = {x: mnist.validation.images, y_: mnist.validation.labels} #直接调用封装好的函数来计算前向传播的结果 y = mnist_inference.inference(x, None) #计算正确率 correcgt_prediction = tf.equal(tf.argmax(y, 1), tf.argmax(y_, 1)) accuracy = tf.reduce_mean(tf.cast(correcgt_prediction, tf.float32)) #通过变量重命名的方式加载模型 variable_averages = tf.train.ExponentialMovingAverage(0.99) variable_to_restore = variable_averages.variables_to_restore() saver = tf.train.Saver(variable_to_restore) #每隔10秒调用一次计算正确率的过程以检测训练过程中正确率的变化 while True: with tf.compat.v1.Session() as sess: ckpt = tf.train.get_checkpoint_state(minist_train.MODEL_SAVE_PATH) if ckpt and ckpt.model_checkpoint_path: #load the model saver.restore(sess, ckpt.model_checkpoint_path) global_step = ckpt.model_checkpoint_path.split('/')[-1].split('-')[-1] accuracy_score = sess.run(accuracy, feed_dict=validate_feed) print("After %s training steps, validation accuracy = %g" % (global_step, accuracy_score)) else: print('No checkpoint file found') return time.sleep(EVAL_INTERVAL_SECS) def main(argv=None): mnist = input_data.read_data_sets(r"D:\Anaconda123\Lib\site-packages\tensorboard\mnist", one_hot=True) evaluate(mnist) if __name__ == '__main__': tf.compat.v1.app.run()对代码进行改进

以下是对代码的改进建议：

1. 在代码开头添加注释，简要说明代码功能和使用方法。

2. 将导入模块的语句放在代码开头。

3. 将模型保存路径和评估时间间隔定义为常量，并使用有意义的变量名。

4. 将计算正确率和加载模型的过程封装为函数。

5. 在主函数中调用评估函数。

改进后的代码如下：

# 该代码实现了使用已训练好的模型对 MNIST 数据集进行评估

import time
import tensorflow.compat.v1 as tf
from tensorflow.examples.tutorials.mnist import input_data
import mnist_inference
import mnist_train

# 定义常量
MODEL_SAVE_PATH = 'model/'
EVAL_INTERVAL_SECS = 10

def evaluate(mnist):
    """
    计算模型在验证集上的正确率
    """
    with tf.Graph().as_default() as g:
        # 定义输入和输出格式
        x = tf.placeholder(tf.float32, [None, mnist_inference.INPUT_NODE], name='x-input')
        y_ = tf.placeholder(tf.float32, [None, mnist_inference.OUTPUT_NODE], name='y-input')

        # 直接调用封装好的函数计算前向传播结果
        y = mnist_inference.inference(x, None)

        # 计算正确率
        correct_prediction = tf.equal(tf.argmax(y, 1), tf.argmax(y_, 1))
        accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))

        # 加载模型
        variable_averages = tf.train.ExponentialMovingAverage(mnist_train.MOVING_AVERAGE_DECAY)
        variables_to_restore = variable_averages.variables_to_restore()
        saver = tf.train.Saver(variables_to_restore)

        # 在验证集上计算正确率
        with tf.Session() as sess:
            ckpt = tf.train.get_checkpoint_state(MODEL_SAVE_PATH)
            if ckpt and ckpt.model_checkpoint_path:
                saver.restore(sess, ckpt.model_checkpoint_path)
                global_step = ckpt.model_checkpoint_path.split('/')[-1].split('-')[-1]
                accuracy_score = sess.run(accuracy, feed_dict={x: mnist.validation.images, y_: mnist.validation.labels})
                print("After %s training steps, validation accuracy = %g" % (global_step, accuracy_score))
            else:
                print('No checkpoint file found')

def main(argv=None):
    # 读取数据集
    mnist = input_data.read_data_sets('MNIST_data', one_hot=True)

    # 每隔一定时间评估模型在验证集上的正确率
    while True:
        evaluate(mnist)
        time.sleep(EVAL_INTERVAL_SECS)

if __name__ == '__main__':
    tf.app.run()