python – 恢复使用迭代器的Tensorflow模型

我有一个使用迭代器训练我的网络的模型;遵循Google现在推荐的新数据集API管道模型.

我读了tfrecord文件,将数据提供给网络,训练得很好,一切顺利,我在训练结束时保存了我的模型,所以我可以在以后运行推理.代码的简化版本如下：

""" Training and saving """

training_dataset = tf.contrib.data.TFRecordDataset(training_record)
training_dataset = training_dataset.map(ds._path_records_parser)
training_dataset = training_dataset.batch(BATCH_SIZE)
with tf.name_scope("iterators"):
  training_iterator = Iterator.from_structure(training_dataset.output_types,training_dataset.output_shapes)
  next_training_element = training_iterator.get_next()
  training_init_op = training_iterator.make_initializer(training_dataset)

def train(num_epochs):
  # compute for the number of epochs
  for e in range(1,num_epochs+1):
    session.run(training_init_op) #initializing iterator here
    while True:
      try:
        images,labels = session.run(next_training_element)
        session.run(optimizer,Feed_dict={x: images,y_true: labels})
      except tf.errors.OutOfRangeError:
        saver_name = './saved_models/ucf-model'
        print("Finished Training Epoch {}".format(e))
        break



    """ Restoring """
# restoring the saved model and its variables
session = tf.Session()
saver = tf.train.import_Meta_graph(r'saved_models\ucf-model.Meta')
saver.restore(session,tf.train.latest_checkpoint('.\saved_models'))
graph = tf.get_default_graph()

# restoring relevant tensors/ops
accuracy = graph.get_tensor_by_name("accuracy/Mean:0") #the tensor that when evaluated returns the mean accuracy of the batch
testing_iterator = graph.get_operation_by_name("iterators/Iterator") #my iterator used in testing.
next_testing_element = graph.get_operation_by_name("iterators/IteratorGetNext") #the GetNext operator for my iterator
# loading my testing set tfrecords
testing_dataset = tf.contrib.data.TFRecordDataset(testing_record_path)
testing_dataset = testing_dataset.map(ds._path_records_parser,num_threads=4,output_buffer_size=BATCH_SIZE*20)
testing_dataset = testing_dataset.batch(BATCH_SIZE)

testing_init_op = testing_iterator.make_initializer(testing_dataset) #to initialize the dataset

with tf.Session() as session:
  session.run(testing_init_op)
  while True:
    try:
      images,labels = session.run(next_testing_element)
      accuracy = session.run(accuracy,Feed_dict={x: test_images,y_true: test_labels}) #error here,x,y_true not defined
    except tf.errors.OutOfRangeError:
      break

我的问题主要是我恢复模型.如何将测试数据提供给网络？

>当我使用testing_iterator = graph.get_operation_by_name(“iterators / Iterator”),next_testing_element = graph.get_operation_by_name(“iterators / IteratorGetNext”)恢复我的Iterator时,出现以下错误：
GetNext()失败,因为迭代器尚未初始化.确保在获取下一个元素之前已为此迭代器运行初始化程序操作.
>所以我尝试使用以下方法初始化我的数据集：testing_init_op = testing_iterator.make_initializer(testing_dataset)).我收到此错误：AttributeError：’Operation’对象没有属性’make_initializer’

另一个问题是,由于正在使用迭代器,因此不需要在training_model中使用占位符,因为迭代器直接将数据提供给图形.但是这样,当我将数据提供给“准确度”操作时,如何在第3行到最后一行恢复我的Feed_dict键？

编辑：如果有人可以建议在迭代器和网络输入之间添加占位符的方法,那么我可以尝试通过评估“准确性”张量来运行图形,同时将数据提供给占位符并完全忽略迭代器.

解决方法

还原已保存的元图时,可以使用name恢复初始化操作,然后再次使用它来初始化输入管道以进行推理.

也就是说,在创建图表时,您可以这样做

dataset_init_op = iterator.make_initializer(dataset,name='dataset_init')

然后执行以下操作恢复此操作：

dataset_init_op = graph.get_operation_by_name('dataset_init')

这是一个自包含的代码片段,用于比较恢复前后的随机初始化模型的结果.

保存迭代器

np.random.seed(42)
data = np.random.random([4,4])
X = tf.placeholder(dtype=tf.float32,shape=[4,4],name='X')
dataset = tf.data.Dataset.from_tensor_slices(X)
iterator = tf.data.Iterator.from_structure(dataset.output_types,dataset.output_shapes)
dataset_next_op = iterator.get_next()

# name the operation
dataset_init_op = iterator.make_initializer(dataset,name='dataset_init')

w = np.random.random([1,4])
W = tf.Variable(w,name='W',dtype=tf.float32)
output = tf.multiply(W,dataset_next_op,name='output')     
sess = tf.Session()
saver = tf.train.Saver()
sess.run(tf.global_variables_initializer())
sess.run(dataset_init_op,Feed_dict={X:data})
while True:
    try:
        print(sess.run(output))
    except tf.errors.OutOfRangeError:
        saver.save(sess,'tmp/',global_step=1002)
    break

然后您可以恢复相同的模型进行推理,如下所示：

恢复已保存的迭代器

np.random.seed(42)
data = np.random.random([4,4])
tf.reset_default_graph()
sess = tf.Session()
saver = tf.train.import_Meta_graph('tmp/-1002.Meta')
ckpt = tf.train.get_checkpoint_state(os.path.dirname('tmp/checkpoint'))
saver.restore(sess,ckpt.model_checkpoint_path)
graph = tf.get_default_graph()

# Restore the init operation
dataset_init_op = graph.get_operation_by_name('dataset_init')

X = graph.get_tensor_by_name('X:0')
output = graph.get_tensor_by_name('output:0')
sess.run(dataset_init_op,Feed_dict={X:data})
while True:
try:
    print(sess.run(output))
except tf.errors.OutOfRangeError:
    break