Combination of numbers with specific order

Question

Fayyaz 2017-10-13

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/361132-combination-of-numbers-with-specific-order

评论： Fayyaz 2017-10-13

采纳的回答： Andrei Bobrov

在 MATLAB Online 中打开

Hi all,

I would like to create a matrix of combination of numbers (with five columns). The number are: 4,6,8,10,12,14

The matrix should be like this:

4 4 4 4 4
4 4 4 4 6
4 4 4 6 6
.
.
.
.
14 14 14 14 14

Please help me out!

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Fayyaz 2017-10-13

编辑：Walter Roberson 2017-10-13

在 MATLAB Online 中打开

image.png

Many thanks for the comment. Your comment made me think about it. I was a bit vague. Please see the attached.

4  4  4  4
4  4  4  6
4  4  6  6
4  6  6  6
6  6  6  6
4  4  4  8
4  4  8  8
4  8  8  8
8  8  8  8
4  4  4  10
4  4  10  10
4  10  10  10
10  10  10  10
4  4  4  12
4  4  12  12
4  12  12  12
12  12  12  12
4  4  4  14
4  4  14  14
4  14  14  14
14  14  14  14
6  6  6  8
6  6  8  8
6  8  8  8
8  8  8  8
6  6  6  10

Walter Roberson 2017-10-13

Probably a couple of for loops is the easiest way to handle it.

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Answer 1

Andrei Bobrov 2017-10-13

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https://ww2.mathworks.cn/matlabcentral/answers/361132-combination-of-numbers-with-specific-order#answer_285608

编辑：Andrei Bobrov 2017-10-13

在 MATLAB Online 中打开

out = nchoosek(kron(4:2:14,ones(1,5)),5);

or

x = kron(4:2:14,ones(1,5));
out = hankel(x(1:end-4),x(end-4:end));

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Fayyaz 2017-10-13

image.png

Dear Andrei, many thanks.

It works but there is a small problem. I got this matrix (with a number of repetitions):

4 4 4 4 4

4 4 4 4 6

4 4 4 4 8

Any recommendation how would I be able to get a unique sequence like:

4 4 4 4 4

4 4 4 4 6

4 4 4 6 6

Thanks in advance.

Andrei Bobrov 2017-10-13

See my answer: part after word "or".

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Answer 2

Walter Roberson 2017-10-13

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https://ww2.mathworks.cn/matlabcentral/answers/361132-combination-of-numbers-with-specific-order#answer_285616

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Slightly vectorized:

V = 4 : 2 : 14;
num_V = length(V);
pattern = [1 1 1 1 2;
           1 1 1 2 2;
           1 1 2 2 2;
           1 2 2 2 2];
num_pattern = size(pattern,1);
nrow = num_pattern * (num_V - 1) + 1;
out = zeros(nrow, 5);
out(1, :) = V(1);
for idx = 2 : num_V
  pair = [V(1), V(idx)];
  this_set = pair(pattern);
  start = 1 + (idx-2) * num_pattern;
  out(start + 1 : start + num_pattern, :) = this_set;
end

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Fayyaz 2017-10-13

Many thanks. It works perfectly. I have already written manually since it was not that long. However, for my next enumeration, I will keep this handy!!

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