captcha_train.py

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import time
from datetime import datetime
import argparse
import sys

import tensorflow as tf
import captcha_model as captcha

FLAGS = None

def run_train():
  """Train CAPTCHA for a number of steps."""

  with tf.Graph().as_default():
    images, labels = captcha.inputs(train=True, batch_size=FLAGS.batch_size)

    logits = captcha.inference(images, keep_prob=0.5)

    loss = captcha.loss(logits, labels)

    train_op = captcha.training(loss)

    saver = tf.train.Saver(tf.global_variables())

    init_op = tf.group(tf.global_variables_initializer(),
                       tf.local_variables_initializer())

    sess = tf.Session()

    sess.run(init_op)

    coord = tf.train.Coordinator()
    threads = tf.train.start_queue_runners(sess=sess, coord=coord)
    try:
      step = 0
      while not coord.should_stop():
        start_time = time.time()
        _, loss_value = sess.run([train_op, loss])
        duration = time.time() - start_time
        if step % 10 == 0:
          print('>> Step %d run_train: loss = %.2f (%.3f sec)' % (step, loss_value,
                                                     duration))
        if step % 100 == 0:
          print('>> %s Saving in %s' % (datetime.now(), FLAGS.checkpoint))
          saver.save(sess, FLAGS.checkpoint, global_step=step)
        step += 1
    except Exception as e:
      print('>> %s Saving in %s' % (datetime.now(), FLAGS.checkpoint))
      saver.save(sess, FLAGS.checkpoint, global_step=step)
      coord.request_stop(e)
    finally:
      coord.request_stop()
    coord.join(threads)
    sess.close()


def main(_):
  if tf.gfile.Exists(FLAGS.train_dir):
    tf.gfile.DeleteRecursively(FLAGS.train_dir)
  tf.gfile.MakeDirs(FLAGS.train_dir)
  run_train()


if __name__ == '__main__':
  parser = argparse.ArgumentParser()
  parser.add_argument(
      '--batch_size',
      type=int,
      default=128,
      help='Batch size.'
  )
  parser.add_argument(
      '--train_dir',
      type=str,
      default='./captcha_train',
      help='Directory where to write event logs.'
  )
  parser.add_argument(
      '--checkpoint',
      type=str,
      default='./captcha_train/captcha',
      help='Directory where to write checkpoint.'
  )
  FLAGS, unparsed = parser.parse_known_args()
  tf.app.run(main=main, argv=[sys.argv[0]] + unparsed)