How to generate and read tensorflow TFRecords files

This article mainly introduces the method of generating and reading tensorflow TFRecords files. It has certain reference value. Now I share it with you. Friends in need can refer to it.

TensorFlow provides TFRecords format to store data uniformly. In theory, TFRecords can store any form of data.

The data in the TFRecords file is stored in the format of tf.train.Example Protocol Buffer. The following code gives the definition of tf.train.Example.

message Example { 
  Features features = 1; 
}; 
message Features { 
  map<string, Feature> feature = 1; 
}; 
message Feature { 
  oneof kind { 
  BytesList bytes_list = 1; 
  FloatList float_list = 2; 
  Int64List int64_list = 3; 
} 
};

The following will introduce how to generate and read tfrecords files:

First introduce the generation of tfrecords files, directly The above code:

from random import shuffle 
import numpy as np 
import glob 
import tensorflow as tf 
import cv2 
import sys 
import os 
 
# 因为我装的是CPU版本的，运行起来会有'warning'，解决方法入下，眼不见为净~ 
os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2' 
 
shuffle_data = True 
image_path = '/path/to/image/*.jpg' 
 
# 取得该路径下所有图片的路径，type（addrs）= list 
addrs = glob.glob(image_path) 
# 标签数据的获得具体情况具体分析，type（labels）= list 
labels = ... 
 
# 这里是打乱数据的顺序 
if shuffle_data: 
  c = list(zip(addrs, labels)) 
  shuffle(c) 
  addrs, labels = zip(*c) 
 
# 按需分割数据集 
train_addrs = addrs[0:int(0.7*len(addrs))] 
train_labels = labels[0:int(0.7*len(labels))] 
 
val_addrs = addrs[int(0.7*len(addrs)):int(0.9*len(addrs))] 
val_labels = labels[int(0.7*len(labels)):int(0.9*len(labels))] 
 
test_addrs = addrs[int(0.9*len(addrs)):] 
test_labels = labels[int(0.9*len(labels)):] 
 
# 上面不是获得了image的地址么，下面这个函数就是根据地址获取图片 
def load_image(addr): # A function to Load image 
  img = cv2.imread(addr) 
  img = cv2.resize(img, (224, 224), interpolation=cv2.INTER_CUBIC) 
  img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB) 
  # 这里/255是为了将像素值归一化到[0，1] 
  img = img / 255. 
  img = img.astype(np.float32) 
  return img 
 
# 将数据转化成对应的属性 
def _int64_feature(value):  
  return tf.train.Feature(int64_list=tf.train.Int64List(value=[value])) 
 
 
def _bytes_feature(value): 
  return tf.train.Feature(bytes_list=tf.train.BytesList(value=[value])) 
 
 
def _float_feature(value): 
  return tf.train.Feature(float_list=tf.train.FloatList(value=[value])) 
 
# 下面这段就开始把数据写入TFRecods文件 
 
train_filename = '/path/to/train.tfrecords' # 输出文件地址 
 
# 创建一个writer来写 TFRecords 文件 
writer = tf.python_io.TFRecordWriter(train_filename) 
 
for i in range(len(train_addrs)): 
  # 这是写入操作可视化处理 
  if not i % 1000: 
    print('Train data: {}/{}'.format(i, len(train_addrs))) 
    sys.stdout.flush() 
  # 加载图片 
  img = load_image(train_addrs[i]) 
 
  label = train_labels[i] 
 
  # 创建一个属性（feature） 
  feature = {'train/label': _int64_feature(label), 
        'train/image': _bytes_feature(tf.compat.as_bytes(img.tostring()))} 
 
  # 创建一个 example protocol buffer 
  example = tf.train.Example(features=tf.train.Features(feature=feature)) 
 
  # 将上面的example protocol buffer写入文件 
  writer.write(example.SerializeToString()) 
 
writer.close() 
sys.stdout.flush()

The above only introduces the generation of the train.tfrecords file. Let’s draw inferences about the rest of the validation and test. .

Next, we will introduce the reading of tfrecords files:

import tensorflow as tf 
import numpy as np 
import matplotlib.pyplot as plt 
import os  
os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2' 
data_path = 'train.tfrecords' # tfrecords 文件的地址 
 
with tf.Session() as sess: 
  # 先定义feature，这里要和之前创建的时候保持一致 
  feature = { 
    'train/image': tf.FixedLenFeature([], tf.string), 
    'train/label': tf.FixedLenFeature([], tf.int64) 
  } 
  # 创建一个队列来维护输入文件列表 
  filename_queue = tf.train.string_input_producer([data_path], num_epochs=1) 
 
  # 定义一个 reader ，读取下一个 record 
  reader = tf.TFRecordReader() 
  _, serialized_example = reader.read(filename_queue) 
 
  # 解析读入的一个record 
  features = tf.parse_single_example(serialized_example, features=feature) 
 
  # 将字符串解析成图像对应的像素组 
  image = tf.decode_raw(features['train/image'], tf.float32) 
 
  # 将标签转化成int32 
  label = tf.cast(features['train/label'], tf.int32) 
 
  # 这里将图片还原成原来的维度 
  image = tf.reshape(image, [224, 224, 3]) 
 
  # 你还可以进行其他一些预处理.... 
 
  # 这里是创建顺序随机 batches(函数不懂的自行百度) 
  images, labels = tf.train.shuffle_batch([image, label], batch_size=10, capacity=30, min_after_dequeue=10) 
 
  # 初始化 
  init_op = tf.group(tf.global_variables_initializer(), tf.local_variables_initializer()) 
  sess.run(init_op) 
 
  # 启动多线程处理输入数据 
  coord = tf.train.Coordinator() 
  threads = tf.train.start_queue_runners(coord=coord) 
 
  .... 
 
  #关闭线程 
  coord.request_stop() 
  coord.join(threads) 
  sess.close()

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