python - 二维数组作为 Pytorch 中的索引

Question

我想使用一组规则“增长”一个矩阵。

规则示例：

0->[[1,1,1],[0,0,0],[2,2,2]],
1->[[2,2,2],[2,2,2],[2,2,2]],
2->[[0,0,0],[0,0,0],[0,0,0]]

增长矩阵的示例：

[[0]]->[[1,1,1],[0,0,0],[2,2,2]]->
[[2,2,2,2,2,2,2,2,2],[2,2,2,2,2,2,2,2,2],[2,2,2,2,2,2,2,2,2],
[1,1,1,1,1,1,1,1,1],[0,0,0,0,0,0,0,0,0],[2,2,2,2,2,2,2,2,2],
[0,0,0,0,0,0,0,0,0],[0,0,0,0,0,0,0,0,0],[0,0,0,0,0,0,0,0,0]]

这是我一直试图在 Pytorch 中工作的代码

rules = np.random.randint(256,size=(10,256,3,3,3))
rules_tensor = torch.randint(256,size=(10,
            256, 3, 3, 3),
            dtype=torch.uint8, device = torch.device('cuda'))

rules = rules[0]
rules_tensor = rules_tensor[0]

seed = np.array([[128]])
seed_tensor = seed_tensor = torch.cuda.ByteTensor([[128]])

decode = np.empty((3**3, 3**3, 3))
decode_tensor = torch.empty((3**3,
                3**3, 3), dtype=torch.uint8,
                device = torch.device('cuda'))

for i in range(3):
    grow = seed
    grow_tensor = seed_tensor
    for j in range(1,4):
        grow = rules[grow,:,:,i].reshape(3**j,-1)
        grow_tensor = rules_tensor[grow_tensor,:,:,i].reshape(3**j,-1)

    decode[..., i] = grow
    decode_tensor[..., i] = grow_tensor

在这一行中，我似乎无法像在 Numpy 中那样选择索引：

grow = rules[grow,:,:,i].reshape(3**j,-1)

有没有办法在 Pytorch 中执行以下操作？

标签： pythonnumpymatrixindexingpytorch

Answer 1

您可以考虑使用torch.index_select()，在重塑结果之前展平您的索引张量：

代码：

import torch
import numpy as np

rules_np = np.array([
    [[1,1,1],[0,0,0],[2,2,2]],  # for value 0
    [[2,2,2],[2,2,2],[2,2,2]],  # for value 1
    [[0,0,0],[0,0,0],[0,0,0]]]) # for value 2, etc.
rules = torch.from_numpy(rules_np).long()
rule_shape = rules[0].shape

seed = torch.zeros(1).long()
num_growth = 2
print("Seed:")
print(seed)

grow = seed
for i in range(num_growth):
    grow = (torch.index_select(rules, 0, grow.view(-1))
            .view(grow.shape + rule_shape)
            .squeeze())
    print("Growth #{}:".format(i))
    print(grow)

日志：

Seed:
tensor([ 0])
Growth #0:
tensor([[ 1,  1,  1], [ 0,  0,  0], [ 2,  2,  2]])
Growth #1:
tensor([[[[ 2,  2,  2], [ 2,  2,  2], [ 2,  2,  2]],
         [[ 2,  2,  2], [ 2,  2,  2], [ 2,  2,  2]],
         [[ 2,  2,  2], [ 2,  2,  2], [ 2,  2,  2]]],

        [[[ 1,  1,  1], [ 0,  0,  0], [ 2,  2,  2]],
         [[ 1,  1,  1], [ 0,  0,  0], [ 2,  2,  2]],
         [[ 1,  1,  1], [ 0,  0,  0], [ 2,  2,  2]]],

        [[[ 0,  0,  0], [ 0,  0,  0], [ 0,  0,  0]],
         [[ 0,  0,  0], [ 0,  0,  0], [ 0,  0,  0]],
         [[ 0,  0,  0], [ 0,  0,  0], [ 0,  0,  0]]]])