来自Tensorflow中TFRecords的训练分类器

Question

我已经有了一些代码从numpy数组中训练分类器。但是，我的训练数据集非常大。似乎推荐的解决方案是使用TFRecords。我尝试将TFRecords与我自己的数据集一起使用失败了，所以我逐渐将代码缩减为最小的玩具。

示例：

import tensorflow as tf

def readsingleexample(serialized):
    print("readsingleexample", serialized)
    feature = dict()
    feature['x'] = tf.FixedLenFeature([], tf.int64)
    feature['label'] = tf.FixedLenFeature([], tf.int64)
    parsed_example = tf.parse_single_example(serialized, features=feature)
    print(parsed_example)
    return parsed_example['x'], parsed_example['label']

def TestParse(filename):
    record_iterator=tf.python_io.tf_record_iterator(path=filename)
    for string_record in record_iterator:
        example=tf.train.Example()
        example.ParseFromString(string_record)
        print(example.features)

def TestRead(filename):
    record_iterator=tf.python_io.tf_record_iterator(path=filename)
    for string_record in record_iterator:
        feats, label = readsingleexample(string_record)
        print(feats, label)

def _int64_feature(value):
    return tf.train.Feature(int64_list=tf.train.Int64List(value=[value]))

def TFRecordsTest(filename):

    example=tf.train.Example(features=tf.train.Features(feature={
        'x': _int64_feature(7),
        'label': _int64_feature(4)
        }))
    writer = tf.python_io.TFRecordWriter(filename)
    writer.write(example.SerializeToString())

    record_iterator=tf.python_io.tf_record_iterator(path=filename)
    for string_record in record_iterator:
        example=tf.train.Example()
        example.ParseFromString(string_record)
        print(example.features)

    dataset=tf.data.TFRecordDataset(filenames=[filename])
    dataset=dataset.map(readsingleexample)
    dataset=dataset.repeat()

    def train_input_fn():
        iterator=dataset.make_one_shot_iterator()
        feats_tensor, labels_tensor = iterator.get_next()
        return {"x":feats_tensor}, labels_tensor

    feature_columns = []
    feature_columns.append(tf.feature_column.numeric_column(key='x'))

    classifier = tf.estimator.DNNClassifier(feature_columns=feature_columns,
                                      hidden_units=[10, 10, 10],
                                      n_classes=2)
    classifier.train(input_fn=train_input_fn, steps=1000)

    return

这会产生以下输出：

feature {
  key: "label"
  value {
    int64_list {
      value: 4
    }
  }
}
feature {
  key: "x"
  value {
    int64_list {
      value: 7
    }
  }
}

readsingleexample Tensor("arg0:0", shape=(), dtype=string)
{'x': <tf.Tensor 'ParseSingleExample/ParseSingleExample:1' shape=() dtype=int64>, 'label': <tf.Tensor 'ParseSingleExample/ParseSingleExample:0' shape=() dtype=int64>}
WARNING:tensorflow:Using temporary folder as model directory: C:\Users\eeark\AppData\Local\Temp\tmpcl47b2ut
Traceback (most recent call last):
  File "<pyshell#2>", line 1, in <module>
    tfrecords_test.TFRecordsTest(fn)
  File "C:\_P4\user_feindselig\_python\tfrecords_test.py", line 60, in TFRecordsTest
    classifier.train(input_fn=train_input_fn, steps=1000)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\estimator\estimator.py", line 352, in train
    loss = self._train_model(input_fn, hooks, saving_listeners)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\estimator\estimator.py", line 812, in _train_model
    features, labels, model_fn_lib.ModeKeys.TRAIN, self.config)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\estimator\estimator.py", line 793, in _call_model_fn
    model_fn_results = self._model_fn(features=features, **kwargs)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\estimator\canned\dnn.py", line 354, in _model_fn
    config=config)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\estimator\canned\dnn.py", line 185, in _dnn_model_fn
    logits = logit_fn(features=features, mode=mode)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\estimator\canned\dnn.py", line 91, in dnn_logit_fn
    features=features, feature_columns=feature_columns)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\feature_column\feature_column.py", line 273, in input_layer
    trainable, cols_to_vars)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\feature_column\feature_column.py", line 198, in _internal_input_layer
    trainable=trainable)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\feature_column\feature_column.py", line 2080, in _get_dense_tensor
    return inputs.get(self)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\feature_column\feature_column.py", line 1883, in get
    transformed = column._transform_feature(self)  # pylint: disable=protected-access
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\feature_column\feature_column.py", line 2048, in _transform_feature
    input_tensor = inputs.get(self.key)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\feature_column\feature_column.py", line 1870, in get
    feature_tensor = self._get_raw_feature_as_tensor(key)
  File "C:\Program Files\Python352\lib\site-packages\tensorflow\python\feature_column\feature_column.py", line 1924, in _get_raw_feature_as_tensor
    key, feature_tensor))
ValueError: Feature (key: x) cannot have rank 0. Give: Tensor("IteratorGetNext:0", shape=(), dtype=int64, device=/device:CPU:0)

错误是什么意思？可能出现什么问题？

Answer 1

以下似乎有效：至少没有出现错误。使用tf.parse_example([serialized], ...)代替tf.parse_single_example(serialized, ...)。 （此外，合成数据中的标签被改为小于类的数量。）

import tensorflow as tf

def readsingleexample(serialized):
    print("readsingleexample", serialized)
    feature = dict()
    feature['x'] = tf.FixedLenFeature([], tf.int64)
    feature['label'] = tf.FixedLenFeature([], tf.int64)
    parsed_example = tf.parse_example([serialized], features=feature)
    print(parsed_example)
    return parsed_example['x'], parsed_example['label']

def TestParse(filename):
    record_iterator=tf.python_io.tf_record_iterator(path=filename)
    for string_record in record_iterator:
        example=tf.train.Example()
        example.ParseFromString(string_record)
        print(example.features)

def TestRead(filename):
    record_iterator=tf.python_io.tf_record_iterator(path=filename)
    for string_record in record_iterator:
        feats, label = readsingleexample(string_record)
        print(feats, label)

def _int64_feature(value):
    return tf.train.Feature(int64_list=tf.train.Int64List(value=[value]))

def TFRecordsTest(filename):

    example=tf.train.Example(features=tf.train.Features(feature={
        'x': _int64_feature(7),
        'label': _int64_feature(0)
        }))
    writer = tf.python_io.TFRecordWriter(filename)
    writer.write(example.SerializeToString())

    record_iterator=tf.python_io.tf_record_iterator(path=filename)
    for string_record in record_iterator:
        example=tf.train.Example()
        example.ParseFromString(string_record)
        print(example.features)

    dataset=tf.data.TFRecordDataset(filenames=[filename])
    dataset=dataset.map(readsingleexample)
    dataset=dataset.repeat()

    def train_input_fn():
        iterator=dataset.make_one_shot_iterator()
        feats_tensor, labels_tensor = iterator.get_next()
        return {'x':feats_tensor}, labels_tensor

    feature_columns = []
    feature_columns.append(tf.feature_column.numeric_column(key='x'))

    classifier = tf.estimator.DNNClassifier(feature_columns=feature_columns,
                                      hidden_units=[10, 10, 10],
                                      n_classes=2)
    classifier.train(input_fn=train_input_fn, steps=1000)

    return

Answer 2

等级0表示它是标量

所以

example=tf.train.Example(features=tf.train.Features(feature={
    'x': [_int64_feature(7)],
    'label': _int64_feature(4)
    }))

将使其排名为1或向量，即添加[]