Matrix with all possibilities

Rik
2012 12 28
4 个回答
更新时间：2021 1 20
4 次查看（30 天）

0 个投票

Dear all,
I would like to create a matrix with all possibilities, such as the following: [1 1 1; 1 1 0; 1 0 1; 0 1 1; 1 0 0; 0 1 0; 0 0 1; 0 0 0]
I have tried to use nchoosek([0 0 0 1 1 1],3) but this function fails in ordering. Furthermore I tried C = npermutek([ones(1,3) zeros(1,3)],3); D = unique(C,'rows'), but this one gives a out of memory error for larger vectors (8 instead of 3). For this function see: http://www.mathworks.com/matlabcentral/fileexchange/11462-npermutek/
How to create such a matrix?

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回答（4 个）

Jan
Jan 2012-12-28

0 个投票

Searching the FileExchange for the terms "combinations" and "permutations" helps to find:
Azzi Abdelmalek
Azzi Abdelmalek 2012-12-28
编辑：Azzi Abdelmalek 2012-12-28

0 个投票

out=[]
n=3
for k=1:n
s=[ones(2^(n-k ),1) ;zeros(2^(n-k ),1)]
s=repmat(s,2^(k-1),1)
out=[out s]
end
Roger Stafford
Roger Stafford 2012-12-29

0 个投票

Here is a variation on Azzi's solution:
A = ones(2^n,n);
p = 1;
for k = 0:n-1
A(p+1:2*p,n-k:n) = [zeros(p,1),A(1:p,n-k+1:n)];
p = 2*p;
end
To count up instead of down, swap the 'ones' and 'zeros' calls.
Antonio Adaldo
Antonio Adaldo 2021-1-20

0 个投票

The matrix that you want is the same as the matrix containing the binary digits of the numbers from zero to seven. For example: "0 0 0" is zero, "0 0 1" is one, "0 1 0" is two, etc.
If you have Communications Toolbox installed, MATLAB offers the function "de2bi" to produce that matrix. For example:
de2bi(0:7)
ans =
0 0 0
1 0 0
0 1 0
1 1 0
0 0 1
1 0 1
0 1 1
1 1 1
Documentation for "de2bi" is found here: https://www.mathworks.com/help/comm/ref/de2bi.html

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Rik
Rik
2012-12-28

回答：

Antonio Adaldo
Antonio Adaldo
2021-1-20

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