Add resnet model. (#273)

resnet/BUILD

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+package(default_visibility = [":internal"])
+
+licenses(["notice"])  # Apache 2.0
+
+exports_files(["LICENSE"])
+
+package_group(
+    name = "internal",
+    packages = [
+        "//resnet/...",
+    ],
+)
+
+filegroup(
+    name = "py_srcs",
+    data = glob([
+        "**/*.py",
+    ]),
+)
+
+py_library(
+    name = "resnet_model",
+    srcs = ["resnet_model.py"],
+)
+
+py_binary(
+    name = "resnet_main",
+    srcs = [
+        "resnet_main.py",
+    ],
+    deps = [
+        ":cifar_input",
+        ":resnet_model",
+    ],
+)
+
+py_library(
+    name = "cifar_input",
+    srcs = ["cifar_input.py"],
+)

resnet/README.md

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+<font size=4><b>Reproduced ResNet on CIFAR-10 and CIFAR-100 dataset.</b></font>
+
+contact: panyx0718 (xpan@google.com)
+
+<b>Dataset:</b>
+
+https://www.cs.toronto.edu/~kriz/cifar.html
+
+<b>Related papers:</b>
+
+Identity Mappings in Deep Residual Networks
+
+https://arxiv.org/pdf/1603.05027v2.pdf
+
+Deep Residual Learning for Image Recognition
+
+https://arxiv.org/pdf/1512.03385v1.pdf
+
+Wide Residual Networks
+
+https://arxiv.org/pdf/1605.07146v1.pdf
+
+<b>Settings:</b>
+
+* Random split 50k training set into 45k/5k train/eval split.
+* Pad to 36x36 and random crop. Horizontal flip. Per-image whitenting. 
+* Momentum optimizer 0.9.
+* Learning rate schedule: 0.1 (40k), 0.01 (60k), 0.001 (>60k).
+* L2 weight decay: 0.002.
+* Batch size: 128. (28-10 wide and 1001 layer bottleneck use 64)
+
+<b>Results:</b>
+
+<left>
+![Precisions](g3doc/cifar_resnet.gif)
+</left>
+<left>
+![Precisions Legends](g3doc/cifar_resnet_legends.gif)
+</left>
+
+
+CIFAR-10 Model|Best Precision|Steps
+--------------|--------------|------
+32 layer|92.5%|~80k
+110 layer|93.6%|~80k
+164 layer bottleneck|94.5%|~80k
+1001 layer bottleneck|94.9%|~80k
+28-10 wide|95%|~90k
+
+CIFAR-100 Model|Best Precision|Steps
+---------------|--------------|-----
+32 layer|68.1%|~45k
+110 layer|71.3%|~60k
+164 layer bottleneck|75.7%|~50k
+1001 layer bottleneck|78.2%|~70k
+28-10 wide|78.3%|~70k
+
+<b>Prerequisite:</b>
+
+1. Install TensorFlow, Bazel.
+
+2. Download CIFAR-10/CIFAR-100 dataset.
+
+```shell
+curl -o cifar-10-binary.tar.gz https://www.cs.toronto.edu/~kriz/cifar-10-binary.tar.gz
+curl -o cifar-100-binary.tar.gz https://www.cs.toronto.edu/~kriz/cifar-100-binary.tar.gz
+```
+
+<b>How to run:</b>
+
+```shell
+# cd to the your workspace.
+# It contains an empty WORKSPACE file, resnet codes and cifar10 dataset.
+ls -R
+  .:
+  cifar10  resnet  WORKSPACE
+
+  ./cifar10:
+  test.bin  train.bin  validation.bin
+
+  ./resnet:
+  BUILD  cifar_input.py  g3doc  README.md  resnet_main.py  resnet_model.py
+
+# Build everything for GPU.
+bazel build -c opt --config=cuda resnet/...
+
+# Train the model.
+bazel-bin/resnet/resnet_main --train_data_path=cifar10/train.bin \
+                             --log_root=/tmp/resnet_model \
+                             --train_dir=/tmp/resnet_model/train \
+                             --dataset='cifar10' \
+                             --num_gpus=1
+
+# Evaluate the model.
+# Avoid running on the same GPU as the training job at the same time,
+# otherwise, you might run out of memory.
+bazel-bin/resnet/resnet_main --eval_data_path=cifar10/test.bin \
+                             --log_root=/tmp/resnet_model \
+                             --eval_dir=/tmp/resnet_model/test \
+                             --mode=eval \
+                             --dataset='cifar10' \
+                             --num_gpus=0
+```

resnet/cifar_input.py

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+# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+
+"""CIFAR dataset input module.
+"""
+
+import tensorflow as tf
+
+
+def build_input(dataset, data_path, batch_size, mode):
+  """Build CIFAR image and labels.
+
+  Args:
+    dataset: Either 'cifar10' or 'cifar100'.
+    data_path: Filename for data.
+    batch_size: Input batch size.
+    mode: Either 'train' or 'eval'.
+  Returns:
+    images: Batches of images. [batch_size, image_size, image_size, 3]
+    labels: Batches of labels. [batch_size, num_classes]
+  Raises:
+    ValueError: when the specified dataset is not supported.
+  """
+  image_size = 32
+  if dataset == 'cifar10':
+    label_bytes = 1
+    label_offset = 0
+    num_classes = 10
+  elif dataset == 'cifar100':
+    label_bytes = 1
+    label_offset = 1
+    num_classes = 100
+  else:
+    raise ValueError('Not supported dataset %s', dataset)
+
+  depth = 3
+  image_bytes = image_size * image_size * depth
+  record_bytes = label_bytes + label_offset + image_bytes
+
+  file_queue = tf.train.string_input_producer([data_path], shuffle=True)
+  # Read examples from files in the filename queue.
+  reader = tf.FixedLengthRecordReader(record_bytes=record_bytes)
+  _, value = reader.read(file_queue)
+
+  # Convert these examples to dense labels and processed images.
+  record = tf.reshape(tf.decode_raw(value, tf.uint8), [record_bytes])
+  label = tf.cast(tf.slice(record, [label_offset], [label_bytes]), tf.int32)
+  # Convert from string to [depth * height * width] to [depth, height, width].
+  depth_major = tf.reshape(tf.slice(record, [label_bytes], [image_bytes]),
+                           [depth, image_size, image_size])
+  # Convert from [depth, height, width] to [height, width, depth].
+  image = tf.cast(tf.transpose(depth_major, [1, 2, 0]), tf.float32)
+
+  if mode == 'train':
+    image = tf.image.resize_image_with_crop_or_pad(
+        image, image_size+4, image_size+4)
+    image = tf.random_crop(image, [image_size, image_size, 3])
+    image = tf.image.random_flip_left_right(image)
+    # Brightness/saturation/constrast provides small gains .2%~.5% on cifar.
+    # image = tf.image.random_brightness(image, max_delta=63. / 255.)
+    # image = tf.image.random_saturation(image, lower=0.5, upper=1.5)
+    # image = tf.image.random_contrast(image, lower=0.2, upper=1.8)
+    image = tf.image.per_image_whitening(image)
+
+    example_queue = tf.RandomShuffleQueue(
+        capacity=16 * batch_size,
+        min_after_dequeue=8 * batch_size,
+        dtypes=[tf.float32, tf.int32],
+        shapes=[[image_size, image_size, depth], [1]])
+    num_threads = 16
+  else:
+    image = tf.image.resize_image_with_crop_or_pad(
+        image, image_size, image_size)
+    image = tf.image.per_image_whitening(image)
+
+    example_queue = tf.FIFOQueue(
+        3 * batch_size,
+        dtypes=[tf.float32, tf.int32],
+        shapes=[[image_size, image_size, depth], [1]])
+    num_threads = 1
+
+  example_enqueue_op = example_queue.enqueue([image, label])
+  tf.train.add_queue_runner(tf.train.queue_runner.QueueRunner(
+      example_queue, [example_enqueue_op] * num_threads))
+
+  # Read 'batch' labels + images from the example queue.
+  images, labels = example_queue.dequeue_many(batch_size)
+  labels = tf.reshape(labels, [batch_size, 1])
+  indices = tf.reshape(tf.range(0, batch_size, 1), [batch_size, 1])
+  labels = tf.sparse_to_dense(
+      tf.concat(1, [indices, labels]),
+      [batch_size, num_classes], 1.0, 0.0)
+
+  assert len(images.get_shape()) == 4
+  assert images.get_shape()[0] == batch_size
+  assert images.get_shape()[-1] == 3
+  assert len(labels.get_shape()) == 2
+  assert labels.get_shape()[0] == batch_size
+  assert labels.get_shape()[1] == num_classes
+
+  # Display the training images in the visualizer.
+  tf.image_summary('images', images)
+  return images, labels

resnet/resnet_main.py

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+# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+
+"""ResNet Train/Eval module.
+"""
+import sys
+import time
+
+import cifar_input
+import numpy as np
+import resnet_model
+import tensorflow as tf
+
+FLAGS = tf.app.flags.FLAGS
+tf.app.flags.DEFINE_string('dataset', 'cifar10', 'cifar10 or cifar100.')
+tf.app.flags.DEFINE_string('mode', 'train', 'train or eval.')
+tf.app.flags.DEFINE_string('train_data_path', '', 'Filename for training data.')
+tf.app.flags.DEFINE_string('eval_data_path', '', 'Filename for eval data')
+tf.app.flags.DEFINE_integer('image_size', 32, 'Image side length.')
+tf.app.flags.DEFINE_string('train_dir', '',
+                           'Directory to keep training outputs.')
+tf.app.flags.DEFINE_string('eval_dir', '',
+                           'Directory to keep eval outputs.')
+tf.app.flags.DEFINE_integer('eval_batch_count', 50,
+                            'Number of batches to eval.')
+tf.app.flags.DEFINE_bool('eval_once', False,
+                         'Whether evaluate the model only once.')
+tf.app.flags.DEFINE_string('log_root', '',
+                           'Directory to keep the checkpoints. Should be a '
+                           'parent directory of FLAGS.train_dir/eval_dir.')
+tf.app.flags.DEFINE_integer('num_gpus', 0,
+                            'Number of gpus used for training. (0 or 1)')
+
+
+def train(hps):
+  """Training loop."""
+  images, labels = cifar_input.build_input(
+      FLAGS.dataset, FLAGS.train_data_path, hps.batch_size, FLAGS.mode)
+  model = resnet_model.ResNet(hps, images, labels, FLAGS.mode)
+  model.build_graph()
+  summary_writer = tf.train.SummaryWriter(FLAGS.train_dir)
+
+  sv = tf.train.Supervisor(logdir=FLAGS.log_root,
+                           is_chief=True,
+                           summary_op=None,
+                           save_summaries_secs=60,
+                           save_model_secs=300,
+                           global_step=model.global_step)
+  sess = sv.prepare_or_wait_for_session()
+
+  step = 0
+  total_prediction = 0
+  correct_prediction = 0
+  precision = 0.0
+  lrn_rate = 0.1
+
+  while not sv.should_stop():
+    (_, summaries, loss, predictions, truth, train_step) = sess.run(
+        [model.train_op, model.summaries, model.cost, model.predictions,
+         model.labels, model.global_step],
+        feed_dict={model.lrn_rate: lrn_rate})
+
+    if train_step < 40000:
+      lrn_rate = 0.1
+    elif train_step < 60000:
+      lrn_rate = 0.01
+    elif train_step < 80000:
+      lrn_rate = 0.001
+    else:
+      lrn_rate = 0.0001
+
+    predictions = np.argmax(predictions, axis=1)
+    truth = np.argmax(truth, axis=1)
+    for (t, p) in zip(truth, predictions):
+      if t == p:
+        correct_prediction += 1
+      total_prediction += 1
+    precision = float(correct_prediction) / total_prediction
+    correct_prediction = total_prediction = 0
+
+    step += 1
+    if step % 100 == 0:
+      precision_summ = tf.Summary()
+      precision_summ.value.add(
+          tag='Precision', simple_value=precision)
+      summary_writer.add_summary(precision_summ, train_step)
+      summary_writer.add_summary(summaries, train_step)
+      tf.logging.info('loss: %.3f, precision: %.3f\n' % (loss, precision))
+      summary_writer.flush()
+
+  sv.Stop()
+
+
+def evaluate(hps):
+  """Eval loop."""
+  images, labels = cifar_input.build_input(
+      FLAGS.dataset, FLAGS.eval_data_path, hps.batch_size, FLAGS.mode)
+  model = resnet_model.ResNet(hps, images, labels, FLAGS.mode)
+  model.build_graph()
+  saver = tf.train.Saver()
+  summary_writer = tf.train.SummaryWriter(FLAGS.eval_dir)
+
+  sess = tf.Session(config=tf.ConfigProto(allow_soft_placement=True))
+  tf.train.start_queue_runners(sess)
+
+  best_precision = 0.0
+  while True:
+    time.sleep(60)
+    try:
+      ckpt_state = tf.train.get_checkpoint_state(FLAGS.log_root)
+    except tf.errors.OutOfRangeError as e:
+      tf.logging.error('Cannot restore checkpoint: %s', e)
+      continue
+    if not (ckpt_state and ckpt_state.model_checkpoint_path):
+      tf.logging.info('No model to eval yet at %s', FLAGS.log_root)
+      continue
+    tf.logging.info('Loading checkpoint %s', ckpt_state.model_checkpoint_path)
+    saver.restore(sess, ckpt_state.model_checkpoint_path)
+
+    total_prediction, correct_prediction = 0, 0
+    for _ in xrange(FLAGS.eval_batch_count):
+      (summaries, loss, predictions, truth, train_step) = sess.run(
+          [model.summaries, model.cost, model.predictions,
+           model.labels, model.global_step])
+
+      best_predictions = np.argmax(predictions, axis=1)
+      truth = np.argmax(truth, axis=1)
+      for (t, p) in zip(truth, best_predictions):
+        if t == p:
+          correct_prediction += 1
+        total_prediction += 1
+
+    precision = 1.0 * correct_prediction / total_prediction
+    best_precision = max(precision, best_precision)
+
+    precision_summ = tf.Summary()
+    precision_summ.value.add(
+        tag='Precision', simple_value=precision)
+    summary_writer.add_summary(precision_summ, train_step)
+    best_precision_summ = tf.Summary()
+    best_precision_summ.value.add(
+        tag='Best Precision', simple_value=best_precision)
+    summary_writer.add_summary(best_precision_summ, train_step)
+    summary_writer.add_summary(summaries, train_step)
+    tf.logging.info('loss: %.3f, precision: %.3f, best precision: %.3f\n' %
+                    (loss, precision, best_precision))
+    summary_writer.flush()
+
+    if FLAGS.eval_once:
+      break
+
+
+def main(_):
+  if FLAGS.num_gpus == 0:
+    dev = '/cpu:0'
+  elif FLAGS.num_gpus == 1:
+    dev = '/gpu:0'
+  else:
+    raise ValueError('Only support 0 or 1 gpu.')
+
+  if FLAGS.mode == 'train':
+    batch_size = 128
+  elif FLAGS.mode == 'eval':
+    batch_size = 100
+
+  if FLAGS.dataset == 'cifar10':
+    num_classes = 10
+  elif FLAGS.dataset == 'cifar100':
+    num_classes = 100
+
+  hps = resnet_model.HParams(batch_size=batch_size,
+                             num_classes=num_classes,
+                             min_lrn_rate=0.0001,
+                             lrn_rate=0.1,
+                             num_residual_units=5,
+                             use_bottleneck=False,
+                             weight_decay_rate=0.0002,
+                             relu_leakiness=0.1,
+                             optimizer='mom')
+
+  with tf.device(dev):
+    if FLAGS.mode == 'train':
+      train(hps)
+    elif FLAGS.mode == 'eval':
+      evaluate(hps)
+
+
+if __name__ == '__main__':
+  tf.app.run()

resnet/resnet_model.py

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+# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+
+"""ResNet model.
+
+Related papers:
+https://arxiv.org/pdf/1603.05027v2.pdf
+https://arxiv.org/pdf/1512.03385v1.pdf
+https://arxiv.org/pdf/1605.07146v1.pdf
+"""
+from collections import namedtuple
+
+import numpy as np
+import tensorflow as tf
+
+from tensorflow.python.training import moving_averages
+
+
+HParams = namedtuple('HParams',
+                     'batch_size, num_classes, min_lrn_rate, lrn_rate, '
+                     'num_residual_units, use_bottleneck, weight_decay_rate, '
+                     'relu_leakiness, optimizer')
+
+
+class ResNet(object):
+  """ResNet model."""
+
+  def __init__(self, hps, images, labels, mode):
+    """ResNet constructor.
+
+    Args:
+      hps: Hyperparameters.
+      images: Batches of images. [batch_size, image_size, image_size, 3]
+      labels: Batches of labels. [batch_size, num_classes]
+      mode: One of 'train' and 'eval'.
+    """
+    self.hps = hps
+    self._images = images
+    self.labels = labels
+    self.mode = mode
+
+    self._extra_train_ops = []
+
+  def build_graph(self):
+    """Build a whole graph for the model."""
+    self.global_step = tf.Variable(0, name='global_step', trainable=False)
+    self._build_model()
+    if self.mode == 'train':
+      self._build_train_op()
+    self.summaries = tf.merge_all_summaries()
+
+  def _stride_arr(self, stride):
+    """Map a stride scalar to the stride array for tf.nn.conv2d."""
+    return [1, stride, stride, 1]
+
+  def _build_model(self):
+    """Build the core model within the graph."""
+    with tf.variable_scope('init'):
+      x = self._images
+      x = self._conv('init_conv', x, 3, 3, 16, self._stride_arr(1))
+
+    strides = [1, 2, 2]
+    activate_before_residual = [True, False, False]
+    if self.hps.use_bottleneck:
+      res_func = self._bottleneck_residual
+      filters = [16, 64, 128, 256]
+    else:
+      res_func = self._residual
+      filters = [16, 16, 32, 64]
+      # Uncomment the following codes to use w28-10 wide residual network.
+      # It is more memory efficient than very deep residual network and has
+      # comparably good performance.
+      # https://arxiv.org/pdf/1605.07146v1.pdf
+      # filters = [16, 160, 320, 640]
+      # Update hps.num_residual_units to 9
+
+    with tf.variable_scope('unit_1_0'):
+      x = res_func(x, filters[0], filters[1], self._stride_arr(strides[0]),
+                   activate_before_residual[0])
+    for i in xrange(1, self.hps.num_residual_units):
+      with tf.variable_scope('unit_1_%d' % i):
+        x = res_func(x, filters[1], filters[1], self._stride_arr(1), False)
+
+    with tf.variable_scope('unit_2_0'):
+      x = res_func(x, filters[1], filters[2], self._stride_arr(strides[1]),
+                   activate_before_residual[1])
+    for i in xrange(1, self.hps.num_residual_units):
+      with tf.variable_scope('unit_2_%d' % i):
+        x = res_func(x, filters[2], filters[2], self._stride_arr(1), False)
+
+    with tf.variable_scope('unit_3_0'):
+      x = res_func(x, filters[2], filters[3], self._stride_arr(strides[2]),
+                   activate_before_residual[2])
+    for i in xrange(1, self.hps.num_residual_units):
+      with tf.variable_scope('unit_3_%d' % i):
+        x = res_func(x, filters[3], filters[3], self._stride_arr(1), False)
+
+    with tf.variable_scope('unit_last'):
+      x = self._batch_norm('final_bn', x)
+      x = self._relu(x, self.hps.relu_leakiness)
+      x = self._global_avg_pool(x)
+
+    with tf.variable_scope('logit'):
+      logits = self._fully_connected(x, self.hps.num_classes)
+      self.predictions = tf.nn.softmax(logits)
+
+    with tf.variable_scope('costs'):
+      xent = tf.nn.softmax_cross_entropy_with_logits(
+          logits, self.labels)
+      self.cost = tf.reduce_mean(xent, name='xent')
+      self.cost += self._decay()
+
+      moving_avg = tf.train.ExponentialMovingAverage(
+          0.99, num_updates=self.global_step, name='moving_avg')
+      self._extra_train_ops.append(moving_avg.apply([self.cost]))
+      tf.scalar_summary('cost', moving_avg.average(self.cost))
+
+  def _build_train_op(self):
+    """Build training specific ops for the graph."""
+    self.lrn_rate = tf.constant(self.hps.lrn_rate, tf.float32)
+    tf.scalar_summary('learning rate', self.lrn_rate)
+
+    trainable_variables = tf.trainable_variables()
+    grads = tf.gradients(self.cost, trainable_variables)
+
+    if self.hps.optimizer == 'sgd':
+      optimizer = tf.train.GradientDescentOptimizer(self.lrn_rate)
+    elif self.hps.optimizer == 'mom':
+      optimizer = tf.train.MomentumOptimizer(self.lrn_rate, 0.9)
+
+    apply_op = optimizer.apply_gradients(
+        zip(grads, trainable_variables),
+        global_step=self.global_step, name='train_step')
+
+    train_ops = [apply_op] + self._extra_train_ops
+    self.train_op = tf.group(*train_ops)
+
+  # TODO(xpan): Consider batch_norm in contrib/layers/python/layers/layers.py
+  def _batch_norm(self, name, x):
+    """Batch normalization."""
+    with tf.variable_scope(name):
+      params_shape = [x.get_shape()[-1]]
+
+      beta = tf.get_variable(
+          'beta', params_shape, tf.float32,
+          initializer=tf.constant_initializer(0.0, tf.float32))
+      gamma = tf.get_variable(
+          'gamma', params_shape, tf.float32,
+          initializer=tf.constant_initializer(1.0, tf.float32))
+
+      if self.mode == 'train':
+        mean, variance = tf.nn.moments(x, [0, 1, 2], name='moments')
+
+        moving_mean = tf.get_variable(
+            'moving_mean', params_shape, tf.float32,
+            initializer=tf.constant_initializer(0.0, tf.float32),
+            trainable=False)
+        moving_variance = tf.get_variable(
+            'moving_variance', params_shape, tf.float32,
+            initializer=tf.constant_initializer(1.0, tf.float32),
+            trainable=False)
+
+        self._extra_train_ops.append(moving_averages.assign_moving_average(
+            moving_mean, mean, 0.9))
+        self._extra_train_ops.append(moving_averages.assign_moving_average(
+            moving_variance, variance, 0.9))
+      else:
+        mean = tf.get_variable(
+            'moving_mean', params_shape, tf.float32,
+            initializer=tf.constant_initializer(0.0, tf.float32),
+            trainable=False)
+        variance = tf.get_variable(
+            'moving_variance', params_shape, tf.float32,
+            initializer=tf.constant_initializer(1.0, tf.float32),
+            trainable=False)
+        tf.histogram_summary(mean.op.name, mean)
+        tf.histogram_summary(variance.op.name, variance)
+      # elipson used to be 1e-5. Maybe 0.001 solves NaN problem in deeper net.
+      y = tf.nn.batch_normalization(
+          x, mean, variance, beta, gamma, 0.001)
+      y.set_shape(x.get_shape())
+      return y
+
+  def _residual(self, x, in_filter, out_filter, stride,
+                activate_before_residual=False):
+    """Residual unit with 2 sub layers."""
+    if activate_before_residual:
+      with tf.variable_scope('shared_activation'):
+        x = self._batch_norm('init_bn', x)
+        x = self._relu(x, self.hps.relu_leakiness)
+        orig_x = x
+    else:
+      with tf.variable_scope('residual_only_activation'):
+        orig_x = x
+        x = self._batch_norm('init_bn', x)
+        x = self._relu(x, self.hps.relu_leakiness)
+
+    with tf.variable_scope('sub1'):
+      x = self._conv('conv1', x, 3, in_filter, out_filter, stride)
+
+    with tf.variable_scope('sub2'):
+      x = self._batch_norm('bn2', x)
+      x = self._relu(x, self.hps.relu_leakiness)
+      x = self._conv('conv2', x, 3, out_filter, out_filter, [1, 1, 1, 1])
+
+    with tf.variable_scope('sub_add'):
+      if in_filter != out_filter:
+        orig_x = tf.nn.avg_pool(orig_x, stride, stride, 'VALID')
+        orig_x = tf.pad(
+            orig_x, [[0, 0], [0, 0], [0, 0],
+                     [(out_filter-in_filter)//2, (out_filter-in_filter)//2]])
+      x += orig_x
+
+    tf.logging.info('image after unit %s', x.get_shape())
+    return x
+
+  def _bottleneck_residual(self, x, in_filter, out_filter, stride,
+                           activate_before_residual=False):
+    """Bottleneck resisual unit with 3 sub layers."""
+    if activate_before_residual:
+      with tf.variable_scope('common_bn_relu'):
+        x = self._batch_norm('init_bn', x)
+        x = self._relu(x, self.hps.relu_leakiness)
+        orig_x = x
+    else:
+      with tf.variable_scope('residual_bn_relu'):
+        orig_x = x
+        x = self._batch_norm('init_bn', x)
+        x = self._relu(x, self.hps.relu_leakiness)
+
+    with tf.variable_scope('sub1'):
+      x = self._conv('conv1', x, 1, in_filter, out_filter/4, stride)
+
+    with tf.variable_scope('sub2'):
+      x = self._batch_norm('bn2', x)
+      x = self._relu(x, self.hps.relu_leakiness)
+      x = self._conv('conv2', x, 3, out_filter/4, out_filter/4, [1, 1, 1, 1])
+
+    with tf.variable_scope('sub3'):
+      x = self._batch_norm('bn3', x)
+      x = self._relu(x, self.hps.relu_leakiness)
+      x = self._conv('conv3', x, 1, out_filter/4, out_filter, [1, 1, 1, 1])
+
+    with tf.variable_scope('sub_add'):
+      if in_filter != out_filter:
+        orig_x = self._conv('project', orig_x, 1, in_filter, out_filter, stride)
+      x += orig_x
+
+    tf.logging.info('image after unit %s', x.get_shape())
+    return x
+
+  def _decay(self):
+    """L2 weight decay loss."""
+    costs = []
+    for var in tf.trainable_variables():
+      if var.op.name.find(r'DW') > 0:
+        costs.append(tf.nn.l2_loss(var))
+        # tf.histogram_summary(var.op.name, var)
+
+    return tf.mul(self.hps.weight_decay_rate, tf.add_n(costs))
+
+  def _conv(self, name, x, filter_size, in_filters, out_filters, strides):
+    """Convolution."""
+    with tf.variable_scope(name):
+      n = filter_size * filter_size * out_filters
+      kernel = tf.get_variable(
+          'DW', [filter_size, filter_size, in_filters, out_filters],
+          tf.float32, initializer=tf.random_normal_initializer(
+              stddev=np.sqrt(2.0/n)))
+      return tf.nn.conv2d(x, kernel, strides, padding='SAME')
+
+  def _relu(self, x, leakiness=0.0):
+    """Relu, with optional leaky support."""
+    return tf.select(tf.less(x, 0.0), leakiness * x, x, name='leaky_relu')
+
+  def _fully_connected(self, x, out_dim):
+    """FullyConnected layer for final output."""
+    x = tf.reshape(x, [self.hps.batch_size, -1])
+    w = tf.get_variable(
+        'DW', [x.get_shape()[1], out_dim],
+        initializer=tf.uniform_unit_scaling_initializer(factor=1.0))
+    b = tf.get_variable('biases', [out_dim],
+                        initializer=tf.constant_initializer())
+    return tf.nn.xw_plus_b(x, w, b)
+
+  def _global_avg_pool(self, x):
+    assert x.get_shape().ndims == 4
+    return tf.reduce_mean(x, [1, 2])