Dynamic matrix columns combinations

Question

mrish 2024-6-11

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2127421-dynamic-matrix-columns-combinations

评论： Stephen23 2024-6-11

Hello,

I would like to find all possible combinations of a matrix columns, with each column contribute a value, in each itteration of a loop. The matrix size changes in each itteration. For example:

A = [1 2 3

4 5 6

7 8 9].

should produce:

1 2 3

1 2 6

1 5 3 etc.

but should not produce:

1 4 2 for example.

My problems:

When insert the matrix to combvec function nothing happens. The function accept vectors - and since I do it with different matrix size in each Itteration of a loop I can't write it manually.
ndgrid also requires vectors - and since I need to choose a combination index in other variable - I'm not clear how this happens.
I don't have combination function in my Matlab version.

Is there a way to define vectors dynamically in a loop? any idea on to how overcome this? Do I need to write a combination function myself?

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Stephen23 2024-6-11

"Is there a way to define vectors dynamically in a loop?"

What exactly do you mean?

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Stephen23 2024-6-11

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2127421-dynamic-matrix-columns-combinations#answer_1470121

编辑：Stephen23 2024-6-11

在 MATLAB Online 中打开

"any idea on to how overcome this? Do I need to write a combination function myself?"

Use NDGRID with some comma-separated lists:

https://www.mathworks.com/matlabcentral/discussions/tips/847976-tutorial-comma-separated-lists-and-how-to-use-them

A = [1,2,3;4,5,6;7,8,9]
A = 3x3
     1     2     3
     4     5     6
     7     8     9
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
C = num2cell(A,1);
N = numel(C);
[C{:}] = ndgrid(C{:});
M = reshape(cat(1+N,C{:}),[],N)
M = 27x3
     1     2     3
     4     2     3
     7     2     3
     1     5     3
     4     5     3
     7     5     3
     1     8     3
     4     8     3
     7     8     3
     1     2     6
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>