image.png
tf.nn.embedding_lookup函数的用法主要是选取一个张量里面索引对应的元素。tf.nn.embedding_lookup（params, ids）:params可以是张量也可以是数组等，id就是对应的索引，其他的参数不介绍。
例如：ids只有一行：
#c = np.random.random([10, 1]) # 随机生成一个10*1的数组
#b = tf.nn.embedding_lookup(c, [1, 3])#查找数组中的序号为1和3的
p=tf.Variable(tf.random_normal([10,1]))#生成10*1的张量
b = tf.nn.embedding_lookup(p, [1, 3])#查找张量中的序号为1和3的
with tf.Session() as sess:
sess.run(tf.global_variables_initializer())
print(sess.run(b))
#print(c)
print(sess.run(p))
print(p)
print(type(p))
输出：
[[0.15791859]
[0.6468804 ]]
[[-0.2737084 ]
[ 0.15791859]
[-0.01315552]
[ 0.6468804 ]
[-1.4090979 ]
[ 2.1583703 ]
[ 1.4137447 ]
[ 0.20688428]
[-0.32815856]
[-1.0601649 ]]
<tf.Variable 'Variable:0' shape=(10, 1) dtype=float32_ref>
<class 'tensorflow.python.ops.variables.Variable'>
分析：输出为张量的第一和第三个元素。
如果ids是多行
import tensorflow as tf
import numpy as np
a = [[0.1, 0.2, 0.3], [1.1, 1.2, 1.3], [2.1, 2.2, 2.3], [3.1, 3.2, 3.3], [4.1, 4.2, 4.3]]
a = np.asarray(a)
idx1 = tf.Variable([0, 2, 3, 1], tf.int32)
idx2 = tf.Variable([[0, 2, 3, 1], [4, 0, 2, 2]], tf.int32)
out1 = tf.nn.embedding_lookup(a, idx1)
out2 = tf.nn.embedding_lookup(a, idx2)
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
print sess.run(out1)
print out1
print '=================='
print sess.run(out2)
print out2
输出：
[[ 0.1 0.2 0.3]
[ 2.1 2.2 2.3]
[ 3.1 3.2 3.3]
[ 1.1 1.2 1.3]]
Tensor("embedding_lookup:0", shape=(4, 3), dtype=float64)
==================
[[[ 0.1 0.2 0.3]
[ 2.1 2.2 2.3]
[ 3.1 3.2 3.3]
[ 1.1 1.2 1.3]]
[[ 4.1 4.2 4.3]
[ 0.1 0.2 0.3]
[ 2.1 2.2 2.3]
[ 2.1 2.2 2.3]]]
Tensor("embedding_lookup_1:0", shape=(2, 4, 3), dtype=float64)
