how to remove repetition in matrix without changing length

Hi,

I'm trying to create an experiment with matlab and I am using 2 columns in a matrix with number I have randomized according to an index.

I cannot however have a repetition within one column and the two columns have to stay separated and keep the length of 36 elements.

so this is how I created my matrix:

for n = 1:6
   l((n-1)*6+1:n*6,1)=n
   l((n-1)*6+1:n*6,2)=[1:6]
end
vec_index=randperm(36)

vec_randomised=l(vec_index',:)

which gives me this:

5     3
   4     2
   4     1
   4     6
   5     5
   6     3
   1     5
   1     2
   1     6
   6     5
   3     2
   6     1
   5     4
   1     4
   2     3
   3     5
   5     2
   2     2
   6     2
   4     3
   2     6
   3     6
   5     1
   2     5
   6     4
   2     1
   6     6
   3     4
   3     3
   4     4
   5     6
   1     1
   2     4
   3     1
   1     3
   4     5

as you can see there are repetitions for example the 3x4 in the first column.

I made a for-loop to detect the repetition but this does not help me to remove them and keeping the same numbers/amount of numbers in the column.

I also tried shuffle but this gives me different numbers.

I hope I need this as I want to couple this array to words and sounds (which I'm also failing at)

Hopefully someone can help! thx

[Jan]

EDITED, Code formatted.

What exactly is your question? I do not really understand this sentence: "I cannot however have a repetition within one column and the two columns have to stay separated and keep the length of 36 elements." Can the 2 columns do anything but staying separated?

What is the criterion for the matrix? Values from 1 to 6, the values in a row must be different, neighboring elements in the columns must be different?

[Ilse Coolen]

I have 6 words and 6 sounds that have to be played together. Each word has to be linked to each sound once and a word can not be the same word in the following trial or a sound can not b the same sound in the following trial if that makes sense.

so in arrays I would have : words: 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 5 5 5 6 6 6 6 6 6 and next to that I would have the sounds: 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6.

It then has to be randomised but I keep getting repetitions

Answer 1

[Guillaume]

with the size of your matrix, a brute force approach of generating a new permutation until it matches your requirement seems feasible. On the few test I did, it only took a maximum of 1 second:

%a better way to generate the original matrix:
numwords = 6;
numsounds = 6; %doesn't have to be the same number as numwords
wordperm = repmat(1:numwords, numsounds, 1);
wordsound = [wordperm(:), repmat([1:numsounds]', numwords, 1)];

%brute force search of random permutation with no two consecutive number in any column
tic
while any(any(diff(wordsound) == 0))
    wordsound = wordsound(randperm(numwords * numsounds), :);
end
toc
wordsound

[Ilse Coolen]

thank you!!!

Answer 2

[harjeet singh]

use this code

for n = 1:6 
    l((n-1)*6+1:n*6,1)=n;
    l((n-1)*6+1:n*6,2)=[1:6];
end

c=1:36;
B=c(randperm(length(l)));
vec_randomised=l(B',:);

[Ilse Coolen]

still get the same numbers following each other

[harjeet singh]

where you are getting the same numbers? in which row?

vec_randomised =

     1     5
     2     5
     5     5
     5     2
     3     4
     6     2
     2     6
     5     3
     6     3
     4     3
     1     1
     3     2
     1     2
     6     1
     2     3
     5     4
     4     4
     2     4
     4     5
     1     3
     6     6
     5     6
     3     6
     2     1
     1     4
     3     1
     6     5
     4     1
     4     6
     5     1
     1     6
     2     2
     3     3
     6     4
     3     5
     4     2

[Ilse Coolen]

not in the rows but in the columns. In the first column it goes: 1 2 5 5 ... this is what I would want to avoid