'combnk' enumeration of combinations

Question

Salad Box 2020-1-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/499242-combnk-enumeration-of-combinations

回答： Stephen23 2020-1-7

采纳的回答： Stephen23

在 MATLAB Online 中打开

Hi,

If I use 'combnk' in a all positive region, it gives me all the possible combinations.

>> c = combnk(1:3,2)
c =
     1     2
     1     3
     2     3

However, if I use 'combnk' in a negative-to-positive region, it only gives me one combination.

>> c = combnk(-1:1,3)
c =
    -1     0     1

What I really like to obtain is something below with all the combinations.

How to achieve it? Should I not use 'combnk' but something else instead?

Please can you help?

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Answer 1

Stephen23 2020-1-7

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https://ww2.mathworks.cn/matlabcentral/answers/499242-combnk-enumeration-of-combinations#answer_409000

在 MATLAB Online 中打开

>> [X,Y,Z] = ndgrid([-1,0,1]);
>> M = [Z(:),Y(:),X(:)]
M =
  -1  -1  -1
  -1  -1   0
  -1  -1   1
  -1   0  -1
  -1   0   0
  -1   0   1
  -1   1  -1
  -1   1   0
  -1   1   1
   0  -1  -1
   0  -1   0
   0  -1   1
   0   0  -1
   0   0   0
   0   0   1
   0   1  -1
   0   1   0
   0   1   1
   1  -1  -1
   1  -1   0
   1  -1   1
   1   0  -1
   1   0   0
   1   0   1
   1   1  -1
   1   1   0
   1   1   1