先放关键代码：

i = tf.train.range_input_producer(NUM_EXPOCHES, num_epochs=1, shuffle=False).dequeue()
inputs = tf.slice(array, [i * BATCH_SIZE], [BATCH_SIZE])

原理解析：

第一行会产生一个队列，队列包含0到NUM_EXPOCHES-1的元素，如果num_epochs有指定，则每个元素只产生num_epochs次，否则循环产生。shuffle指定是否打乱顺序，这里shuffle=False表示队列的元素是按0到NUM_EXPOCHES-1的顺序存储。在Graph运行的时候，每个线程从队列取出元素，假设值为i，然后按照第二行代码切出array的一小段数据作为一个batch。例如NUM_EXPOCHES=3，如果num_epochs=2，则队列的内容是这样子；

0,1,2,0,1,2

队列只有6个元素，这样在训练的时候只能产生6个batch，迭代6次以后训练就结束。

如果num_epochs不指定，则队列内容是这样子：

0,1,2,0,1,2,0,1,2,0,1,2...

队列可以一直生成元素，训练的时候可以产生无限的batch，需要自己控制什么时候停止训练。

下面是完整的演示代码。

数据文件test.txt内容：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35

main.py内容：

import tensorflow as tf
import codecs
 
BATCH_SIZE = 6
NUM_EXPOCHES = 5
 
 
def input_producer():
 array = codecs.open("test.txt").readlines()
	array = map(lambda line: line.strip(), array)
 i = tf.train.range_input_producer(NUM_EXPOCHES, num_epochs=1, shuffle=False).dequeue()
 inputs = tf.slice(array, [i * BATCH_SIZE], [BATCH_SIZE])
 return inputs
 
 
class Inputs(object):
 def __init__(self):
  self.inputs = input_producer()
 
 
def main(*args, **kwargs):
 inputs = Inputs()
 init = tf.group(tf.initialize_all_variables(),
     tf.initialize_local_variables())
 sess = tf.Session()
 coord = tf.train.Coordinator()
 threads = tf.train.start_queue_runners(sess=sess, coord=coord)
 sess.run(init)
 try:
  index = 0
  while not coord.should_stop() and index<10:
   datalines = sess.run(inputs.inputs)
   index += 1
   print("step: %d, batch data: %s" % (index, str(datalines)))
 except tf.errors.OutOfRangeError:
  print("Done traing:-------Epoch limit reached")
 except KeyboardInterrupt:
  print("keyboard interrput detected, stop training")
 finally:
  coord.request_stop()
 coord.join(threads)
 sess.close()
 del sess
	
if __name__ == "__main__":
 main()

输出：

step: 1, batch data: ['1' '2' '3' '4' '5' '6']
step: 2, batch data: ['7' '8' '9' '10' '11' '12']
step: 3, batch data: ['13' '14' '15' '16' '17' '18']
step: 4, batch data: ['19' '20' '21' '22' '23' '24']
step: 5, batch data: ['25' '26' '27' '28' '29' '30']
Done traing:-------Epoch limit reached

如果range_input_producer去掉参数num_epochs=1，则输出：

step: 1, batch data: ['1' '2' '3' '4' '5' '6']
step: 2, batch data: ['7' '8' '9' '10' '11' '12']
step: 3, batch data: ['13' '14' '15' '16' '17' '18']
step: 4, batch data: ['19' '20' '21' '22' '23' '24']
step: 5, batch data: ['25' '26' '27' '28' '29' '30']
step: 6, batch data: ['1' '2' '3' '4' '5' '6']
step: 7, batch data: ['7' '8' '9' '10' '11' '12']
step: 8, batch data: ['13' '14' '15' '16' '17' '18']
step: 9, batch data: ['19' '20' '21' '22' '23' '24']
step: 10, batch data: ['25' '26' '27' '28' '29' '30']