10.5.2 实现

注意，reshape是不会改变数据在内存中的顺序的，而permute是会改变的，举例如下

x = tensor([[[ 0,  1,  2,  3],
           [ 4,  5,  6,  7],
           [ 8,  9, 10, 11]],
          [[12, 13, 14, 15],
           [16, 17, 18, 19],
           [20, 21, 22, 23]]])

如果执行y = x.permute(2, 0, 1)，那么有

y = tensor([[[ 0,  4,  8],
           [12, 16, 20]],
          [[ 1,  5,  9],
           [13, 17, 21]],
          [[ 2,  6, 10],
           [14, 18, 22]],
          [[ 3,  7, 11],
           [15, 19, 23]]])

如果再执行如下代码

cnt=0
for i in range(x.shape[0]):
    for j in range(x.shape[1]):
        for k in range(x.shape[2]):
            if x[i][j][k]!=y[k][i][j]:
                cnt+=1
cnt

会发现输出为$0$