使用 Tensorflow 中的索引为二维张量赋值

Question

我有一个二维张量 A，我希望用另一个张量 B 替换它的非零项，如下所示。

A = tf.constant([[1.0,0,1.0],[0,1.0,0],[1.0,0,1.0]],dtype=tf.float32)
B = tf.constant([1.0,2.0,3.0,4,0,5.0],dtype=tf.float32)

所以我希望最后的 A 为

 A = tf.constant([[1.0,0.0,2.0],[0,3.0,0.0],[4.0,0.0,5.0]],dtype=tf.float32)

然后我得到 A 的非零元素的索引如下

where_nonzero = tf.not_equal(A, tf.constant(0, dtype=tf.float32))
indices = tf.where(where_nonzero)

indices = <tf.Tensor: shape=(5, 2), dtype=int64, numpy=
array([[0, 0],
   [0, 2],
   [1, 1],
   [2, 0],
   [2, 2]])>

有人可以帮忙吗？

Answer 1

IIUC，你应该可以使用 tf.tensor_scatter_nd_update:

import tensorflow as tf

A = tf.constant([[1.0,0,1.0],[0,1.0,0],[1.0,0,1.0]],dtype=tf.float32)
B = tf.constant([1.0, 2.0, 3.0, 4.0, 5.0],dtype=tf.float32)

where_nonzero = tf.not_equal(A, tf.constant(0, dtype=tf.float32))
indices = tf.where(where_nonzero)
A = tf.tensor_scatter_nd_update(A, indices, B)
print(A)

tf.Tensor(
[[1. 0. 2.]
 [0. 3. 0.]
 [4. 0. 5.]], shape=(3, 3), dtype=float32)

Answer 2

你可以试试SparseTensor

c = tf.constant([[0.0, 0.0, 0.0],
                 [0.0, 0.0, 0.0],
                 [0.0, 0.0, 0.0]])

indices = [[1, 1]]  # A list of coordinates to update.

values = [1.0]  # A list of values corresponding to the respective
                # coordinate in indices.

shape = [3, 3]  # The shape of the corresponding dense tensor, same as `c`.

delta = tf.SparseTensor(indices, values, shape)

或scatter_update:

tf.scatter_update(c, indices, values)

使用 Tensorflow 中的索引为二维张量赋值

Assigning values to a 2D tensor using indices in Tensorflow

python

assign

keras

tensorflow

tensor