fully_connected_feed源码分析

基础知识:

argparse:  用于在命令行运行python时,输入参数

例如proxy.py:

import argparse
parser = argparse.ArgumentParser()
parser.add_argument("square", help="display a square of a given number",
                    type=int)
args = parser.parse_args()
print args.square**2

命令行下:

$ python prog.py 4
16
$ python prog.py four
usage: prog.py [-h] square
prog.py: error: argument square: invalid int value: 'four'

解释:

parser.add_argument("square", help="display a square of a given number",
                    type=int)

# 插入参数square,并且要求该参数为int类型
# $ python prog.py 4      

# 16

 os和sys:  os模块负责程序与操作系统的交互，提供了访问操作系统底层的接口;sys模块负责程序与python解释器的交互，提供了一系列的函数和变量，用于操控python的运行时环境。

<os 常用方法>
os.remove(‘path/filename’) 删除文件
os.rename(oldname, newname) 重命名文件
os.walk() 生成目录树下的所有文件名
os.chdir('dirname') 改变目录
os.mkdir/makedirs('dirname')创建目录/多层目录
os.rmdir/removedirs('dirname') 删除目录/多层目录
os.listdir('dirname') 列出指定目录的文件
os.getcwd() 取得当前工作目录
os.chmod() 改变目录权限
os.path.basename(‘path/filename’) 去掉目录路径，返回文件名
os.path.dirname(‘path/filename’) 去掉文件名，返回目录路径
os.path.join(path1[,path2[,...]]) 将分离的各部分组合成一个路径名
os.path.split('path') 返回( dirname(), basename())元组
os.path.splitext() 返回 (filename, extension) 元组
os.path.getatimectimemtime 分别返回最近访问、创建、修改时间
os.path.getsize() 返回文件大小
os.path.exists() 是否存在
os.path.isabs() 是否为绝对路径
os.path.isdir() 是否为目录
os.path.isfile() 是否为文件

<sys 常用方法>
sys.argv 命令行参数List，第一个元素是程序本身路径
sys.modules.keys() 返回所有已经导入的模块列表
sys.exc_info() 获取当前正在处理的异常类,exc_type、exc_value、exc_traceback当前处理的异常详细信息
sys.exit(n) 退出程序，正常退出时exit(0)
sys.hexversion 获取Python解释程序的版本值，16进制格式如：0x020403F0
sys.version 获取Python解释程序的版本信息
sys.maxint 最大的Int值
sys.maxunicode 最大的Unicode值
sys.modules 返回系统导入的模块字段，key是模块名，value是模块
sys.path 返回模块的搜索路径，初始化时使用PYTHONPATH环境变量的值
sys.platform 返回操作系统平台名称
sys.stdout 标准输出
sys.stdin 标准输入
sys.stderr 错误输出
sys.exc_clear() 用来清除当前线程所出现的当前的或最近的错误信息
sys.exec_prefix 返回平台独立的python文件安装的位置
sys.byteorder 本地字节规则的指示器，big-endian平台的值是'big',little-endian平台的值是'little'
sys.copyright 记录python版权相关的东西
sys.api_version 解释器的C的API版本
sys.stdin,sys.stdout,sys.stderr

fully_connected_feed源码分析

import tensorflow as tf
from tensorflow.examples.tutorials.mnist import input_data
from tensorflow.examples.tutorials.mnist import mnist
from six.moves import xrange

# pylint: disable=missing-docstring
import argparse
import os
import sys
import time


# Basic model parameters as external flags.
FLAGS = None


def placeholder_inputs(batch_size):
  """
    定义两个placeholder,同时自定义placeholder的shape
  Args:
    batch_size: 分别定义images_placeholder和labels_placeholder的shape

  Returns:
    images_placeholder: Images placeholder.
    labels_placeholder: Labels placeholder.
  """
  # Note that the shapes of the placeholders match the shapes of the full
  # image and label tensors, except the first dimension is now batch_size
  # rather than the full size of the train or test data sets.
  images_placeholder = tf.placeholder(tf.float32, shape=(batch_size,
                                                         mnist.IMAGE_PIXELS))
  labels_placeholder = tf.placeholder(tf.int32, shape=(batch_size))
  return images_placeholder, labels_placeholder

def fill_feed_dict(data_set, images_pl, labels_pl):
  """
  将data_set放入images_pl和labels_pl的,然后再放入feed_dict中用于动态训练

  Args:
    data_set: 来自于input_data.read_data_sets()的数据集
    images_pl: 来自于laceholder_inputs()的images placeholder
    labels_pl: 来自于laceholder_inputs()的labels placeholder

  Returns:
    feed_dict: 向feed_dict中传入值images_feed和labels_feed
  """
  # Create the feed_dict for the placeholders filled with the next
  # `batch size` examples.
  images_feed, labels_feed = data_set.next_batch(FLAGS.batch_size,
                                                 FLAGS.fake_data)
  feed_dict = {
      images_pl: images_feed,
      labels_pl: labels_feed,
  }
  return feed_dict


def do_eval(sess,
            eval_correct,
            images_placeholder,
            labels_placeholder,
            data_set):
  """Runs one evaluation against the full epoch of data.

  Args:
    sess: The session in which the model has been trained.
    eval_correct: The Tensor that returns the number of correct predictions.
    images_placeholder: The images placeholder.
    labels_placeholder: The labels placeholder.
    data_set: The set of images and labels to evaluate, from
      input_data.read_data_sets().
  """
  # And run one epoch of eval.
  true_count = 0  # Counts the number of correct predictions.
  steps_per_epoch = data_set.num_examples // FLAGS.batch_size
  num_examples = steps_per_epoch * FLAGS.batch_size
  for step in xrange(steps_per_epoch):
    feed_dict = fill_feed_dict(data_set,
                               images_placeholder,
                               labels_placeholder)
    true_count += sess.run(eval_correct, feed_dict=feed_dict)
  precision = float(true_count) / num_examples
  print('Num examples: %d  Num correct: %d  Precision @ 1: %0.04f' %
        (num_examples, true_count, precision))


def run_training():
  """Train MNIST for a number of steps."""
  # Get the sets of images and labels for training, validation, and
  # test on MNIST.
  data_sets = input_data.read_data_sets(FLAGS.input_data_dir, FLAGS.fake_data)

  # Tell TensorFlow that the model will be built into the default Graph.
  with tf.Graph().as_default():
    # Generate placeholders for the images and labels.
    images_placeholder, labels_placeholder = placeholder_inputs(
        FLAGS.batch_size)

    # Build a Graph that computes predictions from the inference model.
    logits = mnist.inference(images_placeholder,
                             FLAGS.hidden1,
                             FLAGS.hidden2)

    # Add to the Graph the Ops for loss calculation.
    loss = mnist.loss(logits, labels_placeholder)

    # Add to the Graph the Ops that calculate and apply gradients.
    train_op = mnist.training(loss, FLAGS.learning_rate)

    # Add the Op to compare the logits to the labels during evaluation.
    eval_correct = mnist.evaluation(logits, labels_placeholder)

    # Build the summary Tensor based on the TF collection of Summaries.
    summary = tf.summary.merge_all()

    # Add the variable initializer Op.
    init = tf.global_variables_initializer()

    # Create a saver for writing training checkpoints.
    saver = tf.train.Saver()

    # Create a session for running Ops on the Graph.
    sess = tf.Session()

    # Instantiate a SummaryWriter to output summaries and the Graph.
    summary_writer = tf.summary.FileWriter(FLAGS.log_dir, sess.graph)

    # And then after everything is built:

    # Run the Op to initialize the variables.
    sess.run(init)

    # Start the training loop.
    for step in xrange(FLAGS.max_steps):
      start_time = time.time()

      # Fill a feed dictionary with the actual set of images and labels
      # for this particular training step.
      feed_dict = fill_feed_dict(data_sets.train,
                                 images_placeholder,
                                 labels_placeholder)

      # Run one step of the model.  The return values are the activations
      # from the `train_op` (which is discarded) and the `loss` Op.  To
      # inspect the values of your Ops or variables, you may include them
      # in the list passed to sess.run() and the value tensors will be
      # returned in the tuple from the call.
      _, loss_value = sess.run([train_op, loss],
                               feed_dict=feed_dict)

      duration = time.time() - start_time

      # Write the summaries and print an overview fairly often.
      if step % 100 == 0:
        # Print status to stdout.
        print('Step %d: loss = %.2f (%.3f sec)' % (step, loss_value, duration))
        # Update the events file.
        summary_str = sess.run(summary, feed_dict=feed_dict)
        summary_writer.add_summary(summary_str, step)
        summary_writer.flush()

      # Save a checkpoint and evaluate the model periodically.
      if (step + 1) % 1000 == 0 or (step + 1) == FLAGS.max_steps:
        checkpoint_file = os.path.join(FLAGS.log_dir, 'model.ckpt')
        saver.save(sess, checkpoint_file, global_step=step)
        # Evaluate against the training set.
        print('Training Data Eval:')
        do_eval(sess,
                eval_correct,
                images_placeholder,
                labels_placeholder,
                data_sets.train)
        # Evaluate against the validation set.
        print('Validation Data Eval:')
        do_eval(sess,
                eval_correct,
                images_placeholder,
                labels_placeholder,
                data_sets.validation)
        # Evaluate against the test set.
        print('Test Data Eval:')
        do_eval(sess,
                eval_correct,
                images_placeholder,
                labels_placeholder,
                data_sets.test)


def main(_):
  if tf.gfile.Exists(FLAGS.log_dir):
    tf.gfile.DeleteRecursively(FLAGS.log_dir)
  tf.gfile.MakeDirs(FLAGS.log_dir)
  run_training()


if __name__ == '__main__':
  parser = argparse.ArgumentParser()
  parser.add_argument(
      '--learning_rate',
      type=float,
      default=0.01,
      help='Initial learning rate.'
  )
  parser.add_argument(
      '--max_steps',
      type=int,
      default=2000,
      help='Number of steps to run trainer.'
  )
  parser.add_argument(
      '--hidden1',
      type=int,
      default=128,
      help='Number of units in hidden layer 1.'
  )
  parser.add_argument(
      '--hidden2',
      type=int,
      default=32,
      help='Number of units in hidden layer 2.'
  )
  parser.add_argument(
      '--batch_size',
      type=int,
      default=100,
      help='Batch size.  Must divide evenly into the dataset sizes.'
  )
  parser.add_argument(
      '--input_data_dir',
      type=str,
      default=os.path.join(os.getenv('TEST_TMPDIR', '/tmp'),
                           'tensorflow/mnist/input_data'),
      help='Directory to put the input data.'
  )
  parser.add_argument(
      '--log_dir',
      type=str,
      default=os.path.join(os.getenv('TEST_TMPDIR', '/tmp'),
                           'tensorflow/mnist/logs/fully_connected_feed'),
      help='Directory to put the log data.'
  )
  parser.add_argument(
      '--fake_data',
      default=False,
      help='If true, uses fake data for unit testing.',
      action='store_true'
  )

  FLAGS, unparsed = parser.parse_known_args()
  tf.app.run(main=main, argv=[sys.argv[0]] + unparsed)