举个例子：

import numpy as np

import tensorflow as tf

data = np.array([[[2],[1]],[[3],[4]],[[6],[7]]])

data = tf.convert_to_tensor(data)

lk = [[0,1],[1,0],[0,0]]

lookup_data = tf.nn.embedding_lookup(data,lk)

init = tf.global_variables_initializer()

先让我们看下不同数据对应的维度：

In [76]: data.shape

Out[76]: (3, 2, 1)

In [77]: np.array(lk).shape

Out[77]: (3, 2)

In [78]: lookup_data

Out[78]: <tf.Tensor 'embedding_lookup_8:0' shape=(3, 2, 2, 1) dtype=int64>

这个是怎么做到的呢？关键的部分来了，看下图：