TensorFlow學(xué)習(xí)筆記:Inception_v3源碼分析

Inception_v3 函數(shù)列表
retrain.py代碼結(jié)構(gòu)清晰卵沉,模塊化非常易懂逼蒙,有部分代碼是為了兼容MobleNet而寫沟沙,可以忽略撕彤。
有些注釋可能很詳細(xì)须肆,有些可能比較少虫溜,后續(xù)可能會(huì)補(bǔ)充游桩,也可能不會(huì)補(bǔ)充牲迫,主要看是否需要改寫。代碼中有tab縮進(jìn)借卧,也有雙空格縮進(jìn)盹憎,有tab的地方肯定是我看過的。如果需要運(yùn)行建議參考:

另外铐刘,代碼還可以參考TensorFlow學(xué)習(xí)筆記之源碼分析(3)---- retrain.py陪每,這個(gè)版本相對(duì)較早,沒有設(shè)計(jì)Moblenet镰吵,不過核心模塊基本相同檩禾,可能函數(shù)名會(huì)有些許改動(dòng)。
具體代碼及注釋如下:

# -*- coding: utf-8 -*-
"""
Created on Mon Oct  9 20:32:19 2017
Retrain with Inception_v3
@author: Dexter
"""
# Copyright 2015 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.
# ==============================================================================
r"""Simple transfer learning with Inception v3 or Mobilenet models.
基于Inception_v3的簡單的遷移學(xué)習(xí)疤祭,支持TensorBoard
With support for TensorBoard.
This example shows how to take a Inception v3 or Mobilenet model trained on
ImageNet images, and train a new top layer that can recognize other classes of
images.
此例展示如何利用(基于ImageNet圖像訓(xùn)練好的)Inception_v3模型盼产,并訓(xùn)練新的頂層以實(shí)現(xiàn)圖像分類
The top layer receives as input a 2048-dimensional vector (1001-dimensional for
Mobilenet) for each image. We train a softmax layer on top of this
representation. Assuming the softmax layer contains N labels, this corresponds
to learning N + 2048*N (or 1001*N)  model parameters corresponding to the
learned biases and weights.
每個(gè)圖像(預(yù)測(cè))里,頂層接收一個(gè)2048維度的向量作為輸入勺馆,在這一表示(基礎(chǔ))上
我們訓(xùn)練一個(gè)softmax層戏售,假設(shè)這個(gè)softmax層含有N個(gè)類別,這對(duì)應(yīng)于學(xué)習(xí)N+2048*N個(gè)
模型參數(shù)對(duì)應(yīng)于學(xué)習(xí)偏差和權(quán)重草穆。
Here's an example, which assumes you have a folder containing class-named
subfolders, each full of images for each label. The example folder flower_photos
should have a structure like this:
這里有一個(gè)例子灌灾,假設(shè)你有一文件夾,其包含以類別命名的子文件夾悲柱,每個(gè)子文件夾中都
放置對(duì)應(yīng)類別的圖片锋喜。示例文件夾flower_photos中含有(這樣的)結(jié)構(gòu):
~/flower_photos/daisy/photo1.jpg
~/flower_photos/daisy/photo2.jpg
...
~/flower_photos/rose/anotherphoto77.jpg
...
~/flower_photos/sunflower/somepicture.jpg
The subfolder names are important, since they define what label is applied to
each image, but the filenames themselves don't matter. Once your images are
prepared, you can run the training with a command like this:
子文件夾的名字很重要,它們定義了每張圖片的歸類標(biāo)簽豌鸡,而每張圖片的名字是什么本身是沒關(guān)系的跑芳。
一旦你的圖片準(zhǔn)備好了,你可以使用如下命令啟動(dòng)訓(xùn)練: 
bash:
bazel build tensorflow/examples/image_retraining:retrain && \
bazel-bin/tensorflow/examples/image_retraining/retrain \
    --image_dir ~/flower_photos

Or, if you have a pip installation of tensorflow, `retrain.py` can be run
without bazel:
bash:
python tensorflow/examples/image_retraining/retrain.py \
    --image_dir ~/flower_photos

Or, if you have a pip installation of tensorflow, `retrain.py` can be run
without bazel:
bash:
python tensorflow/examples/image_retraining/retrain.py \
    --image_dir ~/flower_photos

You can replace the image_dir argument with any folder containing subfolders of
images. The label for each image is taken from the name of the subfolder it's
in.
你可以替換image_dir 參數(shù)為包含所需圖片子文件夾的任何文件直颅。每張圖片的標(biāo)簽來自子文件夾的名字博个。 
This produces a new model file that can be loaded and run by any TensorFlow
program, for example the label_image sample code.
程序?qū)a(chǎn)生一個(gè)新的模型文件用于任何TensorFlow項(xiàng)目的加載和運(yùn)行,例如label_image樣例代碼功偿。
By default this script will use the high accuracy, but comparatively large and
slow Inception v3 model architecture. 
默認(rèn)情況下這個(gè)腳本將使用高精度盆佣,但是相當(dāng)大且慢的Inception_v3模型結(jié)構(gòu)往堡。
It's recommended that you start with this
to validate that you have gathered good training data, but if you want to deploy
on resource-limited platforms, you can try the `--architecture` flag with a
Mobilenet model. For example:
我們推薦使用Inception v3,但是如果因?yàn)槠脚_(tái)的限制共耍,你也可以使用Mobilenet模型:
bash:
python tensorflow/examples/image_retraining/retrain.py \
    --image_dir ~/flower_photos --architecture mobilenet_1.0_224

There are 32 different Mobilenet models to choose from, with a variety of file
size and latency options. The first number can be '1.0', '0.75', '0.50', or
'0.25' to control the size, and the second controls the input image size, either
'224', '192', '160', or '128', with smaller sizes running faster. See
https://research.googleblog.com/2017/06/mobilenets-open-source-models-for.html
for more information on Mobilenet.
To use with TensorBoard:
By default, this script will log summaries to /tmp/retrain_logs directory
Visualize the summaries with this command:
tensorboard --logdir /tmp/retrain_logs
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import argparse
# 用于解析命令行參數(shù)和選項(xiàng)的標(biāo)準(zhǔn)模塊
from datetime import datetime
import hashlib
# 用于加密相關(guān)的操作虑灰,代替了md5模塊和sha模塊,
# 主要提供SHA1痹兜,SHA224穆咐,SHA256,SHA384字旭,SHA512,MD5算法对湃。
import os.path
import random
import re
# 正則化模塊
import sys
# 系統(tǒng)模塊
import tarfile
# 壓縮與解壓縮模塊

import numpy as np
from six.moves import urllib
# Six is a Python 2 and 3 compatibility library
import tensorflow as tf

from tensorflow.python.framework import graph_util
from tensorflow.python.framework import tensor_shape
from tensorflow.python.platform import gfile
from tensorflow.python.util import compat

FLAGS = None

# These are all parameters that are tied to the particular model architecture
# we're using for Inception v3. These include things like tensor names and their
# sizes. If you want to adapt this script to work with another model, you will
# need to update these to reflect the values in the network you're using.
MAX_NUM_IMAGES_PER_CLASS = 2 ** 27 - 1  # ~134M


def create_image_lists(image_dir, testing_percentage, validation_percentage):
    # 從系統(tǒng)文件中獲取圖片并構(gòu)建一個(gè)訓(xùn)練集,以及測(cè)試集和驗(yàn)證集
    # 輸入為含有對(duì)應(yīng)分類的子目錄的目錄遗淳,以及測(cè)試集與驗(yàn)證集的劃分百分比
    # 輸出為一個(gè)對(duì)應(yīng)分類的子目錄入口(字典)拍柒,劃分為訓(xùn)練、測(cè)試屈暗、驗(yàn)證集
    """Builds a list of training images from the file system.
    Analyzes the sub folders in the image directory, splits them into stable
    training, testing, and validation sets, and returns a data structure
    describing the lists of images for each label and their paths.
    Args:
        image_dir: String path to a folder containing subfolders of images.
        testing_percentage: Integer percentage of the images to reserve for tests.
        validation_percentage: Integer percentage of images reserved for validation.
    Returns:
        A dictionary containing an entry for each label subfolder, with images split
        into training, testing, and validation sets within each label.
    """
    # 如果image_dir不存在
    if not gfile.Exists(image_dir):
        tf.logging.error("Image directory '" + image_dir + "' not found.")
        return None
    # 新建存放結(jié)果的字典
    result = {}
    # 通過os.walk遍歷整個(gè)目錄拆讯,獲取子目錄地址,形成一個(gè)列表
    sub_dirs = [x[0] for x in gfile.Walk(image_dir)]
    # The root directory comes first, so skip it.
    # 獲取的列表sub_dirs中第一個(gè)為根目錄养叛,應(yīng)當(dāng)舍去
    is_root_dir = True
    for sub_dir in sub_dirs:
        if is_root_dir:
            is_root_dir = False
            continue
        extensions = ['jpg', 'jpeg', 'JPG', 'JPEG']
        file_list = []
        dir_name = os.path.basename(sub_dir)
        if dir_name == image_dir:
            continue
        tf.logging.info("Looking for images in '" + dir_name + "'")
        for extension in extensions:
            file_glob = os.path.join(image_dir, dir_name, '*.' + extension)
            file_list.extend(gfile.Glob(file_glob))
        if not file_list:
            tf.logging.warning('No files found')
            continue
        if len(file_list) < 20:
            tf.logging.warning(
                'WARNING: Folder has less than 20 images, which may cause issues.')
        elif len(file_list) > MAX_NUM_IMAGES_PER_CLASS:
            tf.logging.warning(
                'WARNING: Folder {} has more than {} images. Some images will '
                'never be selected.'.format(dir_name, MAX_NUM_IMAGES_PER_CLASS))
        label_name = re.sub(r'[^a-z0-9]+', ' ', dir_name.lower())
        training_images = []
        testing_images = []
        validation_images = []
        for file_name in file_list:
            base_name = os.path.basename(file_name)
            # We want to ignore anything after '_nohash_' in the file name when
            # deciding which set to put an image in, the data set creator has a way of
            # grouping photos that are close variations of each other. For example
            # this is used in the plant disease data set to group multiple pictures of
            # the same leaf.
            hash_name = re.sub(r'_nohash_.*$', '', file_name)
            # This looks a bit magical, but we need to decide whether this file should
            # go into the training, testing, or validation sets, and we want to keep
            # existing files in the same set even if more files are subsequently
            # added.
            # To do that, we need a stable way of deciding based on just the file name
            # itself, so we do a hash of that and then use that to generate a
            # probability value that we use to assign it.
            hash_name_hashed = hashlib.sha1(compat.as_bytes(hash_name)).hexdigest()
            percentage_hash = ((int(hash_name_hashed, 16) %
                              (MAX_NUM_IMAGES_PER_CLASS + 1)) *
                             (100.0 / MAX_NUM_IMAGES_PER_CLASS))
            if percentage_hash < validation_percentage:
                validation_images.append(base_name)
            elif percentage_hash < (testing_percentage + validation_percentage):
                testing_images.append(base_name)
            else:
                training_images.append(base_name)
            result[label_name] = {
                'dir': dir_name,
                'training': training_images,
                'testing': testing_images,
                'validation': validation_images,
            }
    return result


def get_image_path(image_lists, label_name, index, image_dir, category):
  """"Returns a path to an image for a label at the given index.
  Args:
    image_lists: Dictionary of training images for each label.
    label_name: Label string we want to get an image for.
    index: Int offset of the image we want. This will be moduloed by the
    available number of images for the label, so it can be arbitrarily large.
    image_dir: Root folder string of the subfolders containing the training
    images.
    category: Name string of set to pull images from - training, testing, or
    validation.
  Returns:
    File system path string to an image that meets the requested parameters.
  """
  if label_name not in image_lists:
    tf.logging.fatal('Label does not exist %s.', label_name)
  label_lists = image_lists[label_name]
  if category not in label_lists:
    tf.logging.fatal('Category does not exist %s.', category)
  category_list = label_lists[category]
  if not category_list:
    tf.logging.fatal('Label %s has no images in the category %s.',
                     label_name, category)
  mod_index = index % len(category_list)
  base_name = category_list[mod_index]
  sub_dir = label_lists['dir']
  full_path = os.path.join(image_dir, sub_dir, base_name)
  return full_path


def get_bottleneck_path(image_lists, label_name, index, bottleneck_dir,
                        category, architecture):
  """"Returns a path to a bottleneck file for a label at the given index.
  Args:
    image_lists: Dictionary of training images for each label.
    label_name: Label string we want to get an image for.
    index: Integer offset of the image we want. This will be moduloed by the
    available number of images for the label, so it can be arbitrarily large.
    bottleneck_dir: Folder string holding cached files of bottleneck values.
    category: Name string of set to pull images from - training, testing, or
    validation.
    architecture: The name of the model architecture.
  Returns:
    File system path string to an image that meets the requested parameters.
  """
  return get_image_path(image_lists, label_name, index, bottleneck_dir,
                        category) + '_' + architecture + '.txt'


def create_model_graph(model_info):
    
    """"Creates a graph from saved GraphDef file and returns a Graph object.
    Args:
        model_info: Dictionary containing information about the model architecture.
    Returns:
        Graph holding the trained Inception network, and various tensors we'll be
        manipulating.
    """
    # 設(shè)置默認(rèn)graph圖
    with tf.Graph().as_default() as graph:
        # 獲取model路徑
        model_path = os.path.join(FLAGS.model_dir, model_info['model_file_name'])
    # 讀取包含model的pb文件
    with gfile.FastGFile(model_path, 'rb') as f:
        graph_def = tf.GraphDef()
        # 讀取字節(jié)流并解析
        graph_def.ParseFromString(f.read())
        # 通過指派model_info獲取bottleneck_tensor與resized_input_tensor
        bottleneck_tensor, resized_input_tensor = (tf.import_graph_def(
            graph_def,
            name='',
            return_elements=[
                model_info['bottleneck_tensor_name'],
                model_info['resized_input_tensor_name'],
            ]))
    # 返回默認(rèn)圖graph與bottleneck_tensor和resized_input_tensor
    return graph, bottleneck_tensor, resized_input_tensor


def run_bottleneck_on_image(sess, image_data, image_data_tensor,
                            decoded_image_tensor, resized_input_tensor,
                            bottleneck_tensor):
  """Runs inference on an image to extract the 'bottleneck' summary layer.
  Args:
    sess: Current active TensorFlow Session.
    image_data: String of raw JPEG data.
    image_data_tensor: Input data layer in the graph.
    decoded_image_tensor: Output of initial image resizing and preprocessing.
    resized_input_tensor: The input node of the recognition graph.
    bottleneck_tensor: Layer before the final softmax.
  Returns:
    Numpy array of bottleneck values.
  """
  # First decode the JPEG image, resize it, and rescale the pixel values.
  resized_input_values = sess.run(decoded_image_tensor,
                                  {image_data_tensor: image_data})
  # Then run it through the recognition network.
  bottleneck_values = sess.run(bottleneck_tensor,
                               {resized_input_tensor: resized_input_values})
  bottleneck_values = np.squeeze(bottleneck_values)
  return bottleneck_values


def maybe_download_and_extract(data_url):
    # 判斷模型是否存在种呐,否則下載
    """Download and extract model tar file.
    If the pretrained model we're using doesn't already exist, this function
    downloads it from the TensorFlow.org website and unpacks it into a directory.
    Args:
        data_url: Web location of the tar file containing the pretrained model.
    """
    dest_directory = FLAGS.model_dir
    if not os.path.exists(dest_directory):
        os.makedirs(dest_directory)
    filename = data_url.split('/')[-1]
    filepath = os.path.join(dest_directory, filename)
    if not os.path.exists(filepath):

        def _progress(count, block_size, total_size):
            sys.stdout.write('\r>> Downloading %s %.1f%%' %
                            (filename,
                            float(count * block_size) / float(total_size) * 100.0))
            sys.stdout.flush()

        filepath, _ = urllib.request.urlretrieve(data_url, filepath, _progress)
        print()
        statinfo = os.stat(filepath)
        tf.logging.info('Successfully downloaded', filename, statinfo.st_size,
                        'bytes.')
    tarfile.open(filepath, 'r:gz').extractall(dest_directory)


def ensure_dir_exists(dir_name):
  """Makes sure the folder exists on disk.
  Args:
    dir_name: Path string to the folder we want to create.
  """
  if not os.path.exists(dir_name):
    os.makedirs(dir_name)


bottleneck_path_2_bottleneck_values = {}


def create_bottleneck_file(bottleneck_path, image_lists, label_name, index,
                           image_dir, category, sess, jpeg_data_tensor,
                           decoded_image_tensor, resized_input_tensor,
                           bottleneck_tensor):
  """Create a single bottleneck file."""
  tf.logging.info('Creating bottleneck at ' + bottleneck_path)
  image_path = get_image_path(image_lists, label_name, index,
                              image_dir, category)
  if not gfile.Exists(image_path):
    tf.logging.fatal('File does not exist %s', image_path)
  image_data = gfile.FastGFile(image_path, 'rb').read()
  try:
    bottleneck_values = run_bottleneck_on_image(
        sess, image_data, jpeg_data_tensor, decoded_image_tensor,
        resized_input_tensor, bottleneck_tensor)
  except Exception as e:
    raise RuntimeError('Error during processing file %s (%s)' % (image_path,
                                                                 str(e)))
  bottleneck_string = ','.join(str(x) for x in bottleneck_values)
  with open(bottleneck_path, 'w') as bottleneck_file:
    bottleneck_file.write(bottleneck_string)


def get_or_create_bottleneck(sess, image_lists, label_name, index, image_dir,
                             category, bottleneck_dir, jpeg_data_tensor,
                             decoded_image_tensor, resized_input_tensor,
                             bottleneck_tensor, architecture):
  """Retrieves or calculates bottleneck values for an image.
  If a cached version of the bottleneck data exists on-disk, return that,
  otherwise calculate the data and save it to disk for future use.
  Args:
    sess: The current active TensorFlow Session.
    image_lists: Dictionary of training images for each label.
    label_name: Label string we want to get an image for.
    index: Integer offset of the image we want. This will be modulo-ed by the
    available number of images for the label, so it can be arbitrarily large.
    image_dir: Root folder string of the subfolders containing the training
    images.
    category: Name string of which set to pull images from - training, testing,
    or validation.
    bottleneck_dir: Folder string holding cached files of bottleneck values.
    jpeg_data_tensor: The tensor to feed loaded jpeg data into.
    decoded_image_tensor: The output of decoding and resizing the image.
    resized_input_tensor: The input node of the recognition graph.
    bottleneck_tensor: The output tensor for the bottleneck values.
    architecture: The name of the model architecture.
  Returns:
    Numpy array of values produced by the bottleneck layer for the image.
  """
  label_lists = image_lists[label_name]
  sub_dir = label_lists['dir']
  sub_dir_path = os.path.join(bottleneck_dir, sub_dir)
  ensure_dir_exists(sub_dir_path)
  bottleneck_path = get_bottleneck_path(image_lists, label_name, index,
                                        bottleneck_dir, category, architecture)
  if not os.path.exists(bottleneck_path):
    create_bottleneck_file(bottleneck_path, image_lists, label_name, index,
                           image_dir, category, sess, jpeg_data_tensor,
                           decoded_image_tensor, resized_input_tensor,
                           bottleneck_tensor)
  with open(bottleneck_path, 'r') as bottleneck_file:
    bottleneck_string = bottleneck_file.read()
  did_hit_error = False
  try:
    bottleneck_values = [float(x) for x in bottleneck_string.split(',')]
  except ValueError:
    tf.logging.warning('Invalid float found, recreating bottleneck')
    did_hit_error = True
  if did_hit_error:
    create_bottleneck_file(bottleneck_path, image_lists, label_name, index,
                           image_dir, category, sess, jpeg_data_tensor,
                           decoded_image_tensor, resized_input_tensor,
                           bottleneck_tensor)
    with open(bottleneck_path, 'r') as bottleneck_file:
      bottleneck_string = bottleneck_file.read()
    # Allow exceptions to propagate here, since they shouldn't happen after a
    # fresh creation
    bottleneck_values = [float(x) for x in bottleneck_string.split(',')]
  return bottleneck_values


def cache_bottlenecks(sess, image_lists, image_dir, bottleneck_dir,
                      jpeg_data_tensor, decoded_image_tensor,
                      resized_input_tensor, bottleneck_tensor, architecture):
    """Ensures all the training, testing, and validation bottlenecks are cached.
    Because we're likely to read the same image multiple times (if there are no
    distortions applied during training) it can speed things up a lot if we
    calculate the bottleneck layer values once for each image during
    preprocessing, and then just read those cached values repeatedly during
    training. Here we go through all the images we've found, calculate those
    values, and save them off.
    Args:
        sess: The current active TensorFlow Session.
        image_lists: Dictionary of training images for each label.
        image_dir: Root folder string of the subfolders containing the training
        images.
        bottleneck_dir: Folder string holding cached files of bottleneck values.
        jpeg_data_tensor: Input tensor for jpeg data from file.
        decoded_image_tensor: The output of decoding and resizing the image.
        resized_input_tensor: The input node of the recognition graph.
        bottleneck_tensor: The penultimate output layer of the graph.
        architecture: The name of the model architecture.
    Returns:
        Nothing.
    """
    how_many_bottlenecks = 0
    ensure_dir_exists(bottleneck_dir)
    for label_name, label_lists in image_lists.items():
        for category in ['training', 'testing', 'validation']:
            category_list = label_lists[category]
            for index, unused_base_name in enumerate(category_list):
                get_or_create_bottleneck(
                    sess, image_lists, label_name, index, image_dir, category,
                    bottleneck_dir, jpeg_data_tensor, decoded_image_tensor,
                    resized_input_tensor, bottleneck_tensor, architecture)

                how_many_bottlenecks += 1
                if how_many_bottlenecks % 100 == 0:
                    tf.logging.info(
                        str(how_many_bottlenecks) + ' bottleneck files created.')


def get_random_cached_bottlenecks(sess, image_lists, how_many, category,
                                  bottleneck_dir, image_dir, jpeg_data_tensor,
                                  decoded_image_tensor, resized_input_tensor,
                                  bottleneck_tensor, architecture):
    # 檢索緩存圖像的BN值
    """檢索緩存圖像的瓶頸值。 
    如果沒有應(yīng)用扭曲弃甥,這個(gè)函數(shù)可以直接從磁盤檢索圖像緩存的瓶頸值爽室。它從指定類別的圖像挑選了一套隨機(jī)的數(shù)據(jù)集。 
    Args: 
        sess:當(dāng)前活動(dòng)的tensorflow會(huì)話潘飘。 
        image_lists:每個(gè)標(biāo)簽的訓(xùn)練圖像的詞典。 
        how_many:如果為正數(shù)掉缺,將選擇一個(gè)隨機(jī)樣本的尺寸大小卜录。如果為負(fù)數(shù),則將檢索所有瓶頸眶明。 
        category:從圖像訓(xùn)練艰毒、測(cè)試或驗(yàn)證集提取的圖像的字符串名稱。 
        bottleneck_dir:保存著緩存文件瓶頸值的文件夾字符串搜囱。 
        image_dir:包含訓(xùn)練圖像的子文件夾的根文件夾字符串丑瞧。 
        jpeg_data_tensor:JPEG圖像數(shù)據(jù)導(dǎo)入的層。 
        bottleneck_tensor:CNN圖的瓶頸輸出層蜀肘。 
    Returns: 
        瓶頸數(shù)組的列表绊汹,它們對(duì)應(yīng)于ground truths和相關(guān)的文件名。 
    """  
    """Retrieves bottleneck values for cached images.
    If no distortions are being applied, this function can retrieve the cached
    bottleneck values directly from disk for images. It picks a random set of
    images from the specified category.
    Args:
        sess: Current TensorFlow Session.
        image_lists: Dictionary of training images for each label.
        how_many: If positive, a random sample of this size will be chosen.
        If negative, all bottlenecks will be retrieved.
        category: Name string of which set to pull from - training, testing, or
        validation.
        bottleneck_dir: Folder string holding cached files of bottleneck values.
        image_dir: Root folder string of the subfolders containing the training
        images.
        jpeg_data_tensor: The layer to feed jpeg image data into.
        decoded_image_tensor: The output of decoding and resizing the image.
        resized_input_tensor: The input node of the recognition graph.
        bottleneck_tensor: The bottleneck output layer of the CNN graph.
        architecture: The name of the model architecture.
    Returns:
        List of bottleneck arrays, their corresponding ground truths, and the
        relevant filenames.
    """
  class_count = len(image_lists.keys())
  bottlenecks = []
  ground_truths = []
  filenames = []
  if how_many >= 0:
    # Retrieve a random sample of bottlenecks.
    for unused_i in range(how_many):
      label_index = random.randrange(class_count)
      label_name = list(image_lists.keys())[label_index]
      image_index = random.randrange(MAX_NUM_IMAGES_PER_CLASS + 1)
      image_name = get_image_path(image_lists, label_name, image_index,
                                  image_dir, category)
      bottleneck = get_or_create_bottleneck(
          sess, image_lists, label_name, image_index, image_dir, category,
          bottleneck_dir, jpeg_data_tensor, decoded_image_tensor,
          resized_input_tensor, bottleneck_tensor, architecture)
      ground_truth = np.zeros(class_count, dtype=np.float32)
      ground_truth[label_index] = 1.0
      bottlenecks.append(bottleneck)
      ground_truths.append(ground_truth)
      filenames.append(image_name)
  else:
    # Retrieve all bottlenecks.
    for label_index, label_name in enumerate(image_lists.keys()):
      for image_index, image_name in enumerate(
          image_lists[label_name][category]):
        image_name = get_image_path(image_lists, label_name, image_index,
                                    image_dir, category)
        bottleneck = get_or_create_bottleneck(
            sess, image_lists, label_name, image_index, image_dir, category,
            bottleneck_dir, jpeg_data_tensor, decoded_image_tensor,
            resized_input_tensor, bottleneck_tensor, architecture)
        ground_truth = np.zeros(class_count, dtype=np.float32)
        ground_truth[label_index] = 1.0
        bottlenecks.append(bottleneck)
        ground_truths.append(ground_truth)
        filenames.append(image_name)
  return bottlenecks, ground_truths, filenames


def get_random_distorted_bottlenecks(
    sess, image_lists, how_many, category, image_dir, input_jpeg_tensor,
    distorted_image, resized_input_tensor, bottleneck_tensor):
  """Retrieves bottleneck values for training images, after distortions.
  If we're training with distortions like crops, scales, or flips, we have to
  recalculate the full model for every image, and so we can't use cached
  bottleneck values. Instead we find random images for the requested category,
  run them through the distortion graph, and then the full graph to get the
  bottleneck results for each.
  Args:
    sess: Current TensorFlow Session.
    image_lists: Dictionary of training images for each label.
    how_many: The integer number of bottleneck values to return.
    category: Name string of which set of images to fetch - training, testing,
    or validation.
    image_dir: Root folder string of the subfolders containing the training
    images.
    input_jpeg_tensor: The input layer we feed the image data to.
    distorted_image: The output node of the distortion graph.
    resized_input_tensor: The input node of the recognition graph.
    bottleneck_tensor: The bottleneck output layer of the CNN graph.
  Returns:
    List of bottleneck arrays and their corresponding ground truths.
  """
  class_count = len(image_lists.keys())
  bottlenecks = []
  ground_truths = []
  for unused_i in range(how_many):
    label_index = random.randrange(class_count)
    label_name = list(image_lists.keys())[label_index]
    image_index = random.randrange(MAX_NUM_IMAGES_PER_CLASS + 1)
    image_path = get_image_path(image_lists, label_name, image_index, image_dir,
                                category)
    if not gfile.Exists(image_path):
      tf.logging.fatal('File does not exist %s', image_path)
    jpeg_data = gfile.FastGFile(image_path, 'rb').read()
    # Note that we materialize the distorted_image_data as a numpy array before
    # sending running inference on the image. This involves 2 memory copies and
    # might be optimized in other implementations.
    distorted_image_data = sess.run(distorted_image,
                                    {input_jpeg_tensor: jpeg_data})
    bottleneck_values = sess.run(bottleneck_tensor,
                                 {resized_input_tensor: distorted_image_data})
    bottleneck_values = np.squeeze(bottleneck_values)
    ground_truth = np.zeros(class_count, dtype=np.float32)
    ground_truth[label_index] = 1.0
    bottlenecks.append(bottleneck_values)
    ground_truths.append(ground_truth)
  return bottlenecks, ground_truths


def should_distort_images(flip_left_right, random_crop, random_scale,
                          random_brightness):
    # 判斷命令行是否有需要進(jìn)行數(shù)據(jù)增強(qiáng)處理:翻轉(zhuǎn)扮宠、剪裁西乖、縮放、明暗
    # 輸出為布爾值:是否需要預(yù)處理
    """Whether any distortions are enabled, from the input flags.
    Args:
        flip_left_right: Boolean whether to randomly mirror images horizontally.
        random_crop: Integer percentage setting the total margin used around the
        crop box.
        random_scale: Integer percentage of how much to vary the scale by.
        random_brightness: Integer range to randomly multiply the pixel values by.
    Returns:
        Boolean value indicating whether any distortions should be applied.
    """
    return (flip_left_right or (random_crop != 0) or (random_scale != 0) or
            (random_brightness != 0))


def add_input_distortions(flip_left_right, random_crop, random_scale,
                          random_brightness, input_width, input_height,
                          input_depth, input_mean, input_std):
  """Creates the operations to apply the specified distortions.
  During training it can help to improve the results if we run the images
  through simple distortions like crops, scales, and flips. These reflect the
  kind of variations we expect in the real world, and so can help train the
  model to cope with natural data more effectively. Here we take the supplied
  parameters and construct a network of operations to apply them to an image.
  Cropping
  ~~~~~~~~
  Cropping is done by placing a bounding box at a random position in the full
  image. The cropping parameter controls the size of that box relative to the
  input image. If it's zero, then the box is the same size as the input and no
  cropping is performed. If the value is 50%, then the crop box will be half the
  width and height of the input. In a diagram it looks like this:
  <       width         >
  +---------------------+
  |                     |
  |   width - crop%     |
  |    <      >         |
  |    +------+         |
  |    |      |         |
  |    |      |         |
  |    |      |         |
  |    +------+         |
  |                     |
  |                     |
  +---------------------+
  Scaling
  ~~~~~~~
  Scaling is a lot like cropping, except that the bounding box is always
  centered and its size varies randomly within the given range. For example if
  the scale percentage is zero, then the bounding box is the same size as the
  input and no scaling is applied. If it's 50%, then the bounding box will be in
  a random range between half the width and height and full size.
  Args:
    flip_left_right: Boolean whether to randomly mirror images horizontally.
    random_crop: Integer percentage setting the total margin used around the
    crop box.
    random_scale: Integer percentage of how much to vary the scale by.
    random_brightness: Integer range to randomly multiply the pixel values by.
    graph.
    input_width: Horizontal size of expected input image to model.
    input_height: Vertical size of expected input image to model.
    input_depth: How many channels the expected input image should have.
    input_mean: Pixel value that should be zero in the image for the graph.
    input_std: How much to divide the pixel values by before recognition.
  Returns:
    The jpeg input layer and the distorted result tensor.
  """

  jpeg_data = tf.placeholder(tf.string, name='DistortJPGInput')
  decoded_image = tf.image.decode_jpeg(jpeg_data, channels=input_depth)
  decoded_image_as_float = tf.cast(decoded_image, dtype=tf.float32)
  decoded_image_4d = tf.expand_dims(decoded_image_as_float, 0)
  margin_scale = 1.0 + (random_crop / 100.0)
  resize_scale = 1.0 + (random_scale / 100.0)
  margin_scale_value = tf.constant(margin_scale)
  resize_scale_value = tf.random_uniform(tensor_shape.scalar(),
                                         minval=1.0,
                                         maxval=resize_scale)
  scale_value = tf.multiply(margin_scale_value, resize_scale_value)
  precrop_width = tf.multiply(scale_value, input_width)
  precrop_height = tf.multiply(scale_value, input_height)
  precrop_shape = tf.stack([precrop_height, precrop_width])
  precrop_shape_as_int = tf.cast(precrop_shape, dtype=tf.int32)
  precropped_image = tf.image.resize_bilinear(decoded_image_4d,
                                              precrop_shape_as_int)
  precropped_image_3d = tf.squeeze(precropped_image, squeeze_dims=[0])
  cropped_image = tf.random_crop(precropped_image_3d,
                                 [input_height, input_width, input_depth])
  if flip_left_right:
    flipped_image = tf.image.random_flip_left_right(cropped_image)
  else:
    flipped_image = cropped_image
  brightness_min = 1.0 - (random_brightness / 100.0)
  brightness_max = 1.0 + (random_brightness / 100.0)
  brightness_value = tf.random_uniform(tensor_shape.scalar(),
                                       minval=brightness_min,
                                       maxval=brightness_max)
  brightened_image = tf.multiply(flipped_image, brightness_value)
  offset_image = tf.subtract(brightened_image, input_mean)
  mul_image = tf.multiply(offset_image, 1.0 / input_std)
  distort_result = tf.expand_dims(mul_image, 0, name='DistortResult')
  return jpeg_data, distort_result


def variable_summaries(var):
  """Attach a lot of summaries to a Tensor (for TensorBoard visualization)."""
  with tf.name_scope('summaries'):
    mean = tf.reduce_mean(var)
    tf.summary.scalar('mean', mean)
    with tf.name_scope('stddev'):
      stddev = tf.sqrt(tf.reduce_mean(tf.square(var - mean)))
    tf.summary.scalar('stddev', stddev)
    tf.summary.scalar('max', tf.reduce_max(var))
    tf.summary.scalar('min', tf.reduce_min(var))
    tf.summary.histogram('histogram', var)


def add_final_training_ops(class_count, final_tensor_name, bottleneck_tensor,
                           bottleneck_tensor_size):
    # 新增一個(gè)softmax和全連接層用作訓(xùn)練
    """Adds a new softmax and fully-connected layer for training.
    We need to retrain the top layer to identify our new classes, so this function
    adds the right operations to the graph, along with some variables to hold the
    weights, and then sets up all the gradients for the backward pass.
    The set up for the softmax and fully-connected layers is based on:
    https://www.tensorflow.org/versions/master/tutorials/mnist/beginners/index.html
    Args:
        class_count: Integer of how many categories of things we're trying to
        recognize.
        final_tensor_name: Name string for the new final node that produces results.
        bottleneck_tensor: The output of the main CNN graph.
        bottleneck_tensor_size: How many entries in the bottleneck vector.
    Returns:
        The tensors for the training and cross entropy results, and tensors for the
        bottleneck input and ground truth input.
    """
    with tf.name_scope('input'):
        bottleneck_input = tf.placeholder_with_default(
            bottleneck_tensor,
            shape=[None, bottleneck_tensor_size],
            name='BottleneckInputPlaceholder')

        ground_truth_input = tf.placeholder(tf.float32,
                                            [None, class_count],
                                            name='GroundTruthInput')

    # Organizing the following ops as `final_training_ops` so they're easier
    # to see in TensorBoard
    layer_name = 'final_training_ops'
    with tf.name_scope(layer_name):
        with tf.name_scope('weights'):
            initial_value = tf.truncated_normal(
                [bottleneck_tensor_size, class_count], stddev=0.001)

            layer_weights = tf.Variable(initial_value, name='final_weights')

            variable_summaries(layer_weights)
        with tf.name_scope('biases'):
            layer_biases = tf.Variable(tf.zeros([class_count]), name='final_biases')
            variable_summaries(layer_biases)
        with tf.name_scope('Wx_plus_b'):
            logits = tf.matmul(bottleneck_input, layer_weights) + layer_biases
            tf.summary.histogram('pre_activations', logits)

    final_tensor = tf.nn.softmax(logits, name=final_tensor_name)
    tf.summary.histogram('activations', final_tensor)

    with tf.name_scope('cross_entropy'):
        cross_entropy = tf.nn.softmax_cross_entropy_with_logits(
            labels=ground_truth_input, logits=logits)
        with tf.name_scope('total'):
            cross_entropy_mean = tf.reduce_mean(cross_entropy)
    tf.summary.scalar('cross_entropy', cross_entropy_mean)

    with tf.name_scope('train'):
        optimizer = tf.train.GradientDescentOptimizer(FLAGS.learning_rate)
        train_step = optimizer.minimize(cross_entropy_mean)

    return (train_step, cross_entropy_mean, bottleneck_input, ground_truth_input,
            final_tensor)


def add_evaluation_step(result_tensor, ground_truth_tensor):
  """Inserts the operations we need to evaluate the accuracy of our results.
  Args:
    result_tensor: The new final node that produces results.
    ground_truth_tensor: The node we feed ground truth data
    into.
  Returns:
    Tuple of (evaluation step, prediction).
  """
  with tf.name_scope('accuracy'):
    with tf.name_scope('correct_prediction'):
      prediction = tf.argmax(result_tensor, 1)
      correct_prediction = tf.equal(
          prediction, tf.argmax(ground_truth_tensor, 1))
    with tf.name_scope('accuracy'):
      evaluation_step = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))
  tf.summary.scalar('accuracy', evaluation_step)
  return evaluation_step, prediction


def save_graph_to_file(sess, graph, graph_file_name):
  output_graph_def = graph_util.convert_variables_to_constants(
      sess, graph.as_graph_def(), [FLAGS.final_tensor_name])
  with gfile.FastGFile(graph_file_name, 'wb') as f:
    f.write(output_graph_def.SerializeToString())
  return


def prepare_file_system():
    # 新建目錄用于寫入TensorBoard的summaries:
    # 判斷是否已經(jīng)存在,如有則刪除
    # Setup the directory we'll write summaries to for TensorBoard
    if tf.gfile.Exists(FLAGS.summaries_dir):
        tf.gfile.DeleteRecursively(FLAGS.summaries_dir)
    tf.gfile.MakeDirs(FLAGS.summaries_dir)
    if FLAGS.intermediate_store_frequency > 0:
        ensure_dir_exists(FLAGS.intermediate_output_graphs_dir)
    return


def create_model_info(architecture):
    # 給定模型名稱获雕,返回包含inception/mobilenet模型結(jié)構(gòu)信息的字典dict
    # 此函數(shù)只定義了inception/mobilenet兩種模型薄腻,其他模型將報(bào)錯(cuò)
    """Given the name of a model architecture, returns information about it.
    There are different base image recognition pretrained models that can be
    retrained using transfer learning, and this function translates from the name
    of a model to the attributes that are needed to download and train with it.
    Args:
        architecture: Name of a model architecture.
    Returns:
        Dictionary of information about the model, or None if the name isn't
        recognized
    Raises:
        ValueError: If architecture name is unknown.
    """
    architecture = architecture.lower()
    # 定義inception_v3模型的參數(shù)信息
    if architecture == 'inception_v3':
        # pylint: disable=line-too-long
        data_url = 'http://download.tensorflow.org/models/image/imagenet/inception-2015-12-05.tgz'
        # pylint: enable=line-too-long
        bottleneck_tensor_name = 'pool_3/_reshape:0'
        bottleneck_tensor_size = 2048
        input_width = 299
        input_height = 299
        input_depth = 3
        resized_input_tensor_name = 'Mul:0'
        model_file_name = 'classify_image_graph_def.pb'
        input_mean = 128
        input_std = 128
    # 定義mobilenet模型的參數(shù)信息(mobilenet含有多個(gè)版本)
    elif architecture.startswith('mobilenet_'):
        parts = architecture.split('_')
        if len(parts) != 3 and len(parts) != 4:
            tf.logging.error("Couldn't understand architecture name '%s'",
                           architecture)
            return None
        version_string = parts[1]
        if (version_string != '1.0' and version_string != '0.75' and
            version_string != '0.50' and version_string != '0.25'):
            tf.logging.error(
              """"The Mobilenet version should be '1.0', '0.75', '0.50', or '0.25',
      but found '%s' for architecture '%s'""",
                version_string, architecture)
            return None
        size_string = parts[2]
        if (size_string != '224' and size_string != '192' and
            size_string != '160' and size_string != '128'):
            tf.logging.error(
                  """The Mobilenet input size should be '224', '192', '160', or '128',
         but found '%s' for architecture '%s'""",
                size_string, architecture)
            return None
        if len(parts) == 3:
            is_quantized = False
        else:
            if parts[3] != 'quantized':
                tf.logging.error(
                    "Couldn't understand architecture suffix '%s' for '%s'", parts[3],
                    architecture)
                return None
            is_quantized = True
        data_url = 'http://download.tensorflow.org/models/mobilenet_v1_'
        data_url += version_string + '_' + size_string + '_frozen.tgz'
        bottleneck_tensor_name = 'MobilenetV1/Predictions/Reshape:0'
        bottleneck_tensor_size = 1001
        input_width = int(size_string)
        input_height = int(size_string)
        input_depth = 3
        resized_input_tensor_name = 'input:0'
        if is_quantized:
            model_base_name = 'quantized_graph.pb'
        else:
            model_base_name = 'frozen_graph.pb'
        model_dir_name = 'mobilenet_v1_' + version_string + '_' + size_string
        model_file_name = os.path.join(model_dir_name, model_base_name)
        input_mean = 127.5
        input_std = 127.5
    # 如果既不是mobilenet模型也不是inception_v3模型則報(bào)錯(cuò)
    else:
        tf.logging.error("Couldn't understand architecture name '%s'", architecture)
        raise ValueError('Unknown architecture', architecture)
    # 返回一個(gè)包含inception/mobilenet模型結(jié)構(gòu)信息的字典dict
    return {
        'data_url': data_url,
        'bottleneck_tensor_name': bottleneck_tensor_name,
        'bottleneck_tensor_size': bottleneck_tensor_size,
        'input_width': input_width,
        'input_height': input_height,
        'input_depth': input_depth,
        'resized_input_tensor_name': resized_input_tensor_name,
        'model_file_name': model_file_name,
        'input_mean': input_mean,
        'input_std': input_std,
    }


def add_jpeg_decoding(input_width, input_height, input_depth, input_mean,
                      input_std):
    """Adds operations that perform JPEG decoding and resizing to the graph..
    Args:
        input_width: Desired width of the image fed into the recognizer graph.
        input_height: Desired width of the image fed into the recognizer graph.
        input_depth: Desired channels of the image fed into the recognizer graph.
        input_mean: Pixel value that should be zero in the image for the graph.
        input_std: How much to divide the pixel values by before recognition.
    Returns:
        Tensors for the node to feed JPEG data into, and the output of the
        preprocessing steps.
    """
  jpeg_data = tf.placeholder(tf.string, name='DecodeJPGInput')
  decoded_image = tf.image.decode_jpeg(jpeg_data, channels=input_depth)
  decoded_image_as_float = tf.cast(decoded_image, dtype=tf.float32)
  decoded_image_4d = tf.expand_dims(decoded_image_as_float, 0)
  resize_shape = tf.stack([input_height, input_width])
  resize_shape_as_int = tf.cast(resize_shape, dtype=tf.int32)
  resized_image = tf.image.resize_bilinear(decoded_image_4d,
                                           resize_shape_as_int)
  offset_image = tf.subtract(resized_image, input_mean)
  mul_image = tf.multiply(offset_image, 1.0 / input_std)
  return jpeg_data, mul_image


def main(_):
    # Needed to make sure the logging output is visible.
    # See https://github.com/tensorflow/tensorflow/issues/3047
    tf.logging.set_verbosity(tf.logging.INFO)

    # Prepare necessary directories that can be used during training
    # 新建目錄用于寫入TensorBoard的summaries:
    # 判斷是否已經(jīng)存在,如有則刪除
    prepare_file_system()

    # Gather information about the model architecture we'll be using.
    # 獲取模型結(jié)構(gòu)信息處在在model_info的字典中以供取用
    model_info = create_model_info(FLAGS.architecture)
    if not model_info:
        tf.logging.error('Did not recognize architecture flag')
        return -1

    # Set up the pre-trained graph.
    # 判斷模型是否存在届案,否則下載
    maybe_download_and_extract(model_info['data_url'])
    # 調(diào)用create_model_graph函數(shù)庵楷,獲取graph, 
    # bottleneck_tensor和resized_image_tensor
    graph, bottleneck_tensor, resized_image_tensor = (
        create_model_graph(model_info))

    # Look at the folder structure, and create lists of all the images.
    # 從系統(tǒng)文件中獲取圖片并構(gòu)建一個(gè)訓(xùn)練集,以及測(cè)試集和驗(yàn)證集
    # 輸入為含有對(duì)應(yīng)分類的子目錄的目錄楣颠,以及測(cè)試集與驗(yàn)證集的劃分百分比
    # 輸出為一個(gè)對(duì)應(yīng)分類的子目錄入口(字典)尽纽,劃分為訓(xùn)練、測(cè)試球碉、驗(yàn)證集
    image_lists = create_image_lists(FLAGS.image_dir, FLAGS.testing_percentage,
                                    FLAGS.validation_percentage)
    # 獲取數(shù)據(jù)集類別數(shù)
    class_count = len(image_lists.keys())
        if class_count == 0:
            tf.logging.error('No valid folders of images found at ' + FLAGS.image_dir)
            return -1
        if class_count == 1:
            tf.logging.error('Only one valid folder of images found at ' +
                            FLAGS.image_dir +
                            ' - multiple classes are needed for classification.')
            return -1

    # See if the command-line flags mean we're applying any distortions.
    # 判斷命令行是否有需要進(jìn)行數(shù)據(jù)增強(qiáng)處理:翻轉(zhuǎn)蜓斧、剪裁、縮放睁冬、明暗
    # 輸出為布爾值:是否需要預(yù)處理
    do_distort_images = should_distort_images(
        FLAGS.flip_left_right, FLAGS.random_crop, FLAGS.random_scale,
        FLAGS.random_brightness)

    with tf.Session(graph=graph) as sess:
        # Set up the image decoding sub-graph.
        jpeg_data_tensor, decoded_image_tensor = add_jpeg_decoding(
            model_info['input_width'], model_info['input_height'],
            model_info['input_depth'], model_info['input_mean'],
            model_info['input_std'])

        if do_distort_images:
            # 圖像增強(qiáng)操作
            # We will be applying distortions, so setup the operations we'll need.
            (distorted_jpeg_data_tensor,
            distorted_image_tensor) = add_input_distortions(
                FLAGS.flip_left_right, FLAGS.random_crop, FLAGS.random_scale,
                FLAGS.random_brightness, model_info['input_width'],
                model_info['input_height'], model_info['input_depth'],
                model_info['input_mean'], model_info['input_std'])
        else:
            # We'll make sure we've calculated the 'bottleneck' image summaries and
            # cached them on disk.
            # 確定計(jì)算bottleneck圖像summaries并緩存在磁盤上
            cache_bottlenecks(sess, image_lists, FLAGS.image_dir,
                                FLAGS.bottleneck_dir, jpeg_data_tensor,
                                decoded_image_tensor, resized_image_tensor,
                                bottleneck_tensor, FLAGS.architecture)
        
        # 添加我們需要訓(xùn)練的新層
        # Add the new layer that we'll be training.
        (train_step, cross_entropy, bottleneck_input, ground_truth_input,
         final_tensor) = add_final_training_ops(
            len(image_lists.keys()), FLAGS.final_tensor_name, bottleneck_tensor,
            model_info['bottleneck_tensor_size'])
        
        # 創(chuàng)建對(duì)新層的精度評(píng)估與預(yù)測(cè)
        # Create the operations we need to evaluate the accuracy of our new layer.
        evaluation_step, prediction = add_evaluation_step(
            final_tensor, ground_truth_input)

        # 合并所有的summaries并寫入到默認(rèn)地址
        # Merge all the summaries and write them out to the summaries_dir
        merged = tf.summary.merge_all()
        train_writer = tf.summary.FileWriter(FLAGS.summaries_dir + '/train',
                                             sess.graph)

        validation_writer = tf.summary.FileWriter(
            FLAGS.summaries_dir + '/validation')
        
        # 初始化所有變量
        # Set up all our weights to their initial default values.
        init = tf.global_variables_initializer()
        sess.run(init)
        
        # 按照命令行要求運(yùn)行多個(gè)周期的訓(xùn)練
        # Run the training for as many cycles as requested on the command line.
        for i in range(FLAGS.how_many_training_steps):
            # 獲取一批輸入瓶頸值挎春,用以增強(qiáng)(扭曲)處理或者存儲(chǔ)在磁盤上
            # Get a batch of input bottleneck values, either calculated fresh every
            # time with distortions applied, or from the cache stored on disk.
            
            # 增強(qiáng)處理
            if do_distort_images:
                (train_bottlenecks,
                 train_ground_truth) = get_random_distorted_bottlenecks(
                    sess, image_lists, FLAGS.train_batch_size, 'training',
                    FLAGS.image_dir, distorted_jpeg_data_tensor,
                    distorted_image_tensor, resized_image_tensor, bottleneck_tensor)
            # 獲取一批對(duì)應(yīng)圖像的BN值
            else:
                (train_bottlenecks,
                 train_ground_truth, _) = get_random_cached_bottlenecks(
                    sess, image_lists, FLAGS.train_batch_size, 'training',
                    FLAGS.bottleneck_dir, FLAGS.image_dir, jpeg_data_tensor,
                    decoded_image_tensor, resized_image_tensor, bottleneck_tensor,
                    FLAGS.architecture)
            # 給(計(jì)算流圖)graph提供BN值和相應(yīng)的ground truth,然后運(yùn)行訓(xùn)練過程豆拨。
            # 捕捉訓(xùn)練的summaries用以TensorBoard
            # Feed the bottlenecks and ground truth into the graph, and run a training
            # step. Capture training summaries for TensorBoard with the `merged` op.
            # TensorBoard部分:
            train_summary, _ = sess.run(
                [merged, train_step],
                feed_dict={bottleneck_input: train_bottlenecks,
                            ground_truth_input: train_ground_truth})
            train_writer.add_summary(train_summary, i)

            # 每隔一段時(shí)間直奋,打印計(jì)算流圖的訓(xùn)練程度
            # Every so often, print out how well the graph is training.
            is_last_step = (i + 1 == FLAGS.how_many_training_steps)
            # 循環(huán),每個(gè)FLAGS.eval_step_interval間隔打印一次施禾,
            # 若為最后一次循環(huán)脚线,打印一次
            if (i % FLAGS.eval_step_interval) == 0 or is_last_step:
                train_accuracy, cross_entropy_value = sess.run(
                    [evaluation_step, cross_entropy],
                    feed_dict={bottleneck_input: train_bottlenecks,
                           ground_truth_input: train_ground_truth})
                           
                tf.logging.info('%s: Step %d: Train accuracy = %.1f%%' %
                            (datetime.now(), i, train_accuracy * 100))
                tf.logging.info('%s: Step %d: Cross entropy = %f' %
                            (datetime.now(), i, cross_entropy_value))
                # 從驗(yàn)證集提取一個(gè)batch的BN數(shù)據(jù)            
                validation_bottlenecks, validation_ground_truth, _ = (
                    get_random_cached_bottlenecks(
                        sess, image_lists, FLAGS.validation_batch_size, 'validation',
                        FLAGS.bottleneck_dir, FLAGS.image_dir, jpeg_data_tensor,
                        decoded_image_tensor, resized_image_tensor, bottleneck_tensor,
                        FLAGS.architecture))
                # 運(yùn)行驗(yàn)證部分,為TensorBoard收集訓(xùn)練summaries
                # Run a validation step and capture training summaries for TensorBoard
                # with the `merged` op.
                validation_summary, validation_accuracy = sess.run(
                    [merged, evaluation_step],
                    feed_dict={bottleneck_input: validation_bottlenecks,
                                ground_truth_input: validation_ground_truth})
                validation_writer.add_summary(validation_summary, i)
                tf.logging.info('%s: Step %d: Validation accuracy = %.1f%% (N=%d)' %
                                (datetime.now(), i, validation_accuracy * 100,
                                len(validation_bottlenecks)))
            
            # 保存臨時(shí)數(shù)據(jù)/中間量
            # Store intermediate results
            intermediate_frequency = FLAGS.intermediate_store_frequency

            if (intermediate_frequency > 0 and (i % intermediate_frequency == 0)
                and i > 0):
                intermediate_file_name = (FLAGS.intermediate_output_graphs_dir +
                                          'intermediate_' + str(i) + '.pb')
                tf.logging.info('Save intermediate result to : ' +
                                intermediate_file_name)
                save_graph_to_file(sess, graph, intermediate_file_name)

        # 至此弥搞,已經(jīng)完成所有訓(xùn)練邮绿,現(xiàn)在最后的測(cè)試集(之前訓(xùn)練沒涉及過的數(shù)據(jù))上
        # 進(jìn)行最后的測(cè)試評(píng)估
        # We've completed all our training, so run a final test evaluation on
        # some new images we haven't used before.
        
        # 從測(cè)試集中提取數(shù)據(jù)
        test_bottlenecks, test_ground_truth, test_filenames = (
            get_random_cached_bottlenecks(
                sess, image_lists, FLAGS.test_batch_size, 'testing',
                FLAGS.bottleneck_dir, FLAGS.image_dir, jpeg_data_tensor,
                decoded_image_tensor, resized_image_tensor, bottleneck_tensor,
                FLAGS.architecture))
                
        # 評(píng)估
        test_accuracy, predictions = sess.run(
            [evaluation_step, prediction],
            feed_dict={bottleneck_input: test_bottlenecks,
                       ground_truth_input: test_ground_truth})
        tf.logging.info('Final test accuracy = %.1f%% (N=%d)' %
                        (test_accuracy * 100, len(test_bottlenecks)))

        if FLAGS.print_misclassified_test_images:
            tf.logging.info('=== MISCLASSIFIED TEST IMAGES ===')
            for i, test_filename in enumerate(test_filenames):
                if predictions[i] != test_ground_truth[i].argmax():
                    tf.logging.info('%70s  %s' %
                              (test_filename,
                               list(image_lists.keys())[predictions[i]]))
        
        # 將訓(xùn)練好的最后一層的權(quán)重和偏置變量固化為常量
        # Write out the trained graph and labels with the weights stored as
        # constants.
        save_graph_to_file(sess, graph, FLAGS.output_graph)
        with gfile.FastGFile(FLAGS.output_labels, 'w') as f:
            f.write('\n'.join(image_lists.keys()) + '\n')

# 命令行定義
if __name__ == '__main__':
  parser = argparse.ArgumentParser()
  parser.add_argument(
      '--image_dir',
      type=str,
      default='',
      help='Path to folders of labeled images.'
  )
  parser.add_argument(
      '--output_graph',
      type=str,
      default='/tmp/output_graph.pb',
      help='Where to save the trained graph.'
  )
  parser.add_argument(
      '--intermediate_output_graphs_dir',
      type=str,
      default='/tmp/intermediate_graph/',
      help='Where to save the intermediate graphs.'
  )
  parser.add_argument(
      '--intermediate_store_frequency',
      type=int,
      default=0,
      help="""\
         How many steps to store intermediate graph. If "0" then will not
         store.\
      """
  )
  parser.add_argument(
      '--output_labels',
      type=str,
      default='/tmp/output_labels.txt',
      help='Where to save the trained graph\'s labels.'
  )
  parser.add_argument(
      '--summaries_dir',
      type=str,
      default='/tmp/retrain_logs',
      help='Where to save summary logs for TensorBoard.'
  )
  parser.add_argument(
      '--how_many_training_steps',
      type=int,
      default=4000,
      help='How many training steps to run before ending.'
  )
  parser.add_argument(
      '--learning_rate',
      type=float,
      default=0.01,
      help='How large a learning rate to use when training.'
  )
  parser.add_argument(
      '--testing_percentage',
      type=int,
      default=10,
      help='What percentage of images to use as a test set.'
  )
  parser.add_argument(
      '--validation_percentage',
      type=int,
      default=10,
      help='What percentage of images to use as a validation set.'
  )
  parser.add_argument(
      '--eval_step_interval',
      type=int,
      default=10,
      help='How often to evaluate the training results.'
  )
  parser.add_argument(
      '--train_batch_size',
      type=int,
      default=100,
      help='How many images to train on at a time.'
  )
  parser.add_argument(
      '--test_batch_size',
      type=int,
      default=-1,
      help="""\
      How many images to test on. This test set is only used once, to evaluate
      the final accuracy of the model after training completes.
      A value of -1 causes the entire test set to be used, which leads to more
      stable results across runs.\
      """
  )
  parser.add_argument(
      '--validation_batch_size',
      type=int,
      default=100,
      help="""\
      How many images to use in an evaluation batch. This validation set is
      used much more often than the test set, and is an early indicator of how
      accurate the model is during training.
      A value of -1 causes the entire validation set to be used, which leads to
      more stable results across training iterations, but may be slower on large
      training sets.\
      """
  )
  parser.add_argument(
      '--print_misclassified_test_images',
      default=False,
      help="""\
      Whether to print out a list of all misclassified test images.\
      """,
      action='store_true'
  )
  parser.add_argument(
      '--model_dir',
      type=str,
      default='/tmp/imagenet',
      help="""\
      Path to classify_image_graph_def.pb,
      imagenet_synset_to_human_label_map.txt, and
      imagenet_2012_challenge_label_map_proto.pbtxt.\
      """
  )
  parser.add_argument(
      '--bottleneck_dir',
      type=str,
      default='/tmp/bottleneck',
      help='Path to cache bottleneck layer values as files.'
  )
  parser.add_argument(
      '--final_tensor_name',
      type=str,
      default='final_result',
      help="""\
      The name of the output classification layer in the retrained graph.\
      """
  )
  parser.add_argument(
      '--flip_left_right',
      default=False,
      help="""\
      Whether to randomly flip half of the training images horizontally.\
      """,
      action='store_true'
  )
  parser.add_argument(
      '--random_crop',
      type=int,
      default=0,
      help="""\
      A percentage determining how much of a margin to randomly crop off the
      training images.\
      """
  )
  parser.add_argument(
      '--random_scale',
      type=int,
      default=0,
      help="""\
      A percentage determining how much to randomly scale up the size of the
      training images by.\
      """
  )
  parser.add_argument(
      '--random_brightness',
      type=int,
      default=0,
      help="""\
      A percentage determining how much to randomly multiply the training image
      input pixels up or down by.\
      """
  )
  parser.add_argument(
      '--architecture',
      type=str,
      default='inception_v3',
      help="""\
      Which model architecture to use. 'inception_v3' is the most accurate, but
      also the slowest. For faster or smaller models, chose a MobileNet with the
      form 'mobilenet_<parameter size>_<input_size>[_quantized]'. For example,
      'mobilenet_1.0_224' will pick a model that is 17 MB in size and takes 224
      pixel input images, while 'mobilenet_0.25_128_quantized' will choose a much
      less accurate, but smaller and faster network that's 920 KB on disk and
      takes 128x128 images. See https://research.googleblog.com/2017/06/mobilenets-open-source-models-for.html
      for more information on Mobilenet.\
      """)
  FLAGS, unparsed = parser.parse_known_args()
  tf.app.run(main=main, argv=[sys.argv[0]] + unparsed)

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