How can i make a partition matrix

Question

Jesus Montiel 2019-11-9

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回答： Praveen Iyyappan Valsala 2019-11-9

I tried to make a mxn partition matrix that all her columns sum 1.0, i have this, but is very slow

c=5; k=3;
matrixTemp = zeros(c, k);
randoms = [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9];
idx_r = zeros(1,k);
for i = 1:c
    s = 0;
     while s ~= 1
          idx_r = randperm(9,k);
           s = sum(randoms(idx_r));
     end
     matrixTemp(i,:) = randoms(idx_r);
end

It is posible more easy?

The partition matrix is the same that fuzzy c means.

I need this for example:

c1 | 0.5 0.6 0.1

c2 | 0,2 0.2 0.5

c3 | 0.3 0.2 0.4

----------------------

R | 1.0 1.0 1.0 % sum each column equals to 1.0

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Answer 1

JESUS DAVID ARIZA ROYETH 2019-11-9

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在 MATLAB Online 中打开

If you are not interested in decimals, just add one, the solution is easy:

c=5;
k=3;
matrixTemp=rand(c,k);
matrixTemp=matrixTemp./sum(matrixTemp)

if you want the entire matrix to have only one decimal place :

c=5;
k=3;
while true
matrixTemp=rand(c,k);
matrixTemp=matrixTemp./sum(matrixTemp);
matrixTemp=round(matrixTemp*10)/10;
if prod(prod(matrixTemp))~=0
    break;
end
end
disp(matrixTemp)

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Jesus Montiel 2019-11-9

Thanks a lot, the first example works fine and faster.

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Answer 2

Praveen Iyyappan Valsala 2019-11-9

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/490180-how-can-i-make-a-partition-matrix#answer_400661

在 MATLAB Online 中打开

If you want to list all possible partitions. Not suitable for large k.

randoms = 0.1:0.1:0.9;
%Index of all permutations with repetitions
[k1,k2,k3] = ndgrid(1:length(randoms)) ; %manually type all k;)
allperm = [k1(:) k2(:) k3(:)] ; 
% use the idex to set up permutation matrix of random
random_allperm=randoms(allperm); 
%Pick the permuations with sum==1
AllPartitions=randoms(allperm((sum(random_allperm,2)==1),:));
%% pick c number of partitions according to your needs
c=5; 
disp(AllPartitions(randperm(length(AllPartitions),c),:))