将N ^ 2个3x3矩阵级联为3Nx3N矩阵 [英] concatenation of N^2 3x3 matrixes into a 3Nx3N matrix

问题描述

我有N ^ 2个矩阵. 每个矩阵都是3x3矩阵. 将它们串联到3Nx3N矩阵的一种方法是编写 A(:,:,i)= # 3x3 matrix i=1:N^2

I have N^2 matrixes. Each one is a 3x3 matrix. One way to concatenation them to a 3Nx3N matrix is to write A(:,:,i)= # 3x3 matrix i=1:N^2

B=[A11 A12 ..A1N;A21 ...A2N;...] 但是当N大时，是一件繁琐的工作. 您提供什么?

B=[A11 A12 ..A1N;A21 ...A2N;...] But When N is large is a tedious work. What do you offer?

推荐答案

这是一个非常快的单行代码，仅使用 PERMUTE :

Here's a really fast one-liner that only uses RESHAPE and PERMUTE:

B = reshape(permute(reshape(A,3,3*N,N),[2 1 3]),3*N,3*N).';

和测试:

>> N=2;
>> A = rand(3,3,N^2)
A(:,:,1) =
    0.5909    0.6571    0.8082
    0.7118    0.6090    0.7183
    0.4694    0.9588    0.5582
A(:,:,2) =
    0.1791    0.6844    0.6286
    0.4164    0.4140    0.5833
    0.1380    0.1099    0.8970
A(:,:,3) =
    0.2232    0.2355    0.1214
    0.1782    0.6873    0.3394
    0.5645    0.4745    0.9763
A(:,:,4) =
    0.5334    0.7559    0.9984
    0.8454    0.7618    0.1065
    0.0549    0.5029    0.3226

>> B = reshape(permute(reshape(A,3,3*N,N),[2 1 3]),3*N,3*N).'
B =
    0.5909    0.6571    0.8082    0.1791    0.6844    0.6286
    0.7118    0.6090    0.7183    0.4164    0.4140    0.5833
    0.4694    0.9588    0.5582    0.1380    0.1099    0.8970
    0.2232    0.2355    0.1214    0.5334    0.7559    0.9984
    0.1782    0.6873    0.3394    0.8454    0.7618    0.1065
    0.5645    0.4745    0.9763    0.0549    0.5029    0.3226

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