tf.segment_sum和tf.unsorted_segment_sum理解实例

本文来自 guotong1988 的CSDN 博客 ，全文地址请点击：https://blog.csdn.net/guotong1988/article/details/77622790

import tensorflow as tf
c = tf.constant([[1,2,3,4], [-1,-2,-3,-4], [5,6,7,8]])
result = tf.segment_sum(c, tf.constant([0, 0, 1]))#第二个参数长度必须为3
result_ = tf.segment_sum(c, tf.constant([0, 1, 1]))
result__ = tf.segment_sum(c, tf.constant([0, 1, 2]))
result2 = tf.unsorted_segment_sum(c, tf.constant([2, 1, 1]),3)#第二个参数长度必须为3
result3 = tf.unsorted_segment_sum(c, tf.constant([1, 0, 1]),2)
#result4 = tf.unsorted_segment_sum(c, tf.constant([2, 0, 1]),2) #错误，segment_ids[0] = 2 is out of range [0, 2)
result4 = tf.unsorted_segment_sum(c, tf.constant([2, 0, 1]),3)
result5 = tf.unsorted_segment_sum(c, tf.constant([3, 1, 0]),5)
sess = tf.Session()
print("result")
print(sess.run(result))
print("result_")
print(sess.run(result_))
print("result__")
print(sess.run(result__))
print("result2")
print(sess.run(result2))
print("result3")
print(sess.run(result3))
print("result4")
print(sess.run(result4))
print("result5")
print(sess.run(result5))

运行结果：

result 
[[0 0 0 0] 
 [5 6 7 8]] 
result_ 
[[1 2 3 4] 
 [4 4 4 4]] 
result__ 
[[ 1  2  3  4] 
 [-1 -2 -3 -4] 
 [ 5  6  7  8]] 
result2 
[[0 0 0 0] 
 [4 4 4 4] 
 [1 2 3 4]] 
result3 
[[-1 -2 -3 -4] 
 [ 6  8 10 12]] 
result4 
[[-1 -2 -3 -4] 
 [ 5  6  7  8] 
 [ 1  2  3  4]] 
result5 
[[ 5  6  7  8] 
 [-1 -2 -3 -4] 
 [ 0  0  0  0] 
 [ 1  2  3  4] 
 [ 0  0  0  0]]

将索引值相同的进行求和，其余的按顺序计算。