How to randomly select an element in adjacent entries in a matrix in for loop

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0 个投票

here's my code:

    % code
  for j=1:tmax
    for i=1:n
    if mat(i)==0 && rand() < r*(1-(zerfre)^2);
        idx = 1 + fix(rand(1,1)*numel(mat)); 
        mat(i)=mat(idx);
    elseif mat(i)==1 && rand() < r*(1-(onefre)^2);
        idx = 1 + fix(rand(1,1)*numel(mat));
        mat(i)= mat(idx);
    elseif mat(i)==2 && rand() < r*(1-(twofre)^2);
        idx = 1 + fix(rand(1,1)*numel(mat));
        mat(i)= mat(idx);
    elseif mat(i)==3 && rand() < r*(1-(thrfre)^2);
        idx = 1 + fix(rand(1,1)*numel(mat));
        mat(i)= mat(idx);
    elseif mat(i)==4 && rand() < r*(1-(foufre)^2);
        idx = 1 + fix(rand(1,1)*numel(mat));
        mat(i)= mat(idx);
    elseif mat(i)==5 && rand() < r*(1-(fivfre)^2);
        idx = 1 + fix(rand(1,1)*numel(mat));
        mat(i)= mat(idx);
    end
    last=mat;
    end  
    % code

Basically I'm updating my initial matrix mat with probability rules. What the rule does is, with some probability, it's replacing the entry with another entry that's randomly selected from the rest of the entire matrix.

Instead of this, I need to randomly select an element from an adjacent neighbourhood of entries, then replace the old entry with that.

By adjacent I mean within the closest 10*10 entries.

How would I do this?

Thanks a lot for your help!

4 个评论
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Image Analyst 2013-4-3

If I'm processing element 85 and I want to replace it with some other element from 75 to 95, taken at random, then what does it matter if mat(85) is 3 or 1 or pi or 42 or whatever? Who cares what it is? Yet you check for it.

Edgaris Rhomer 2013-4-3

I haven't coded this yet and I guess thats why you're not satisfied with my code. Later on it's going to matter to me if mat(85) is 3 or 1, because what I'm ultimately interested in seeing is the rise of a majority language, (i.e. the most frequent entry) and how a special minority language like French is doing. Later on, what I hope to do is I'll detect some clusters of French, then I'll reduce the switching probability so that French is more likely to stay there than other languages, etc.

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