How can i make a partition matrix

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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

Accepted Answer

JESUS DAVID ARIZA ROYETH
JESUS DAVID ARIZA ROYETH on 9 Nov 2019
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)
  1 Comment
Jesus Montiel
Jesus Montiel on 9 Nov 2019
Thanks a lot, the first example works fine and faster.

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More Answers (1)

Praveen Iyyappan Valsala
Praveen Iyyappan Valsala on 9 Nov 2019
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),:))

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