How can I use the output of "sprintf" to read the content of a matrix

Dear all,

I am trying to use a loop to read into different matrices which are: results_USA, results_UK, results_JAP and results_UK. I am trying to do it with a loop using sprintf

%% here is my code

c={'USA','EUR','JAP','UK'};

for j=1:length(c)

for i=0:10

   AA=sprintf('results_%s',c{j})

 [zMin,idx]=min(AA(:,i+1:i+5),[],2);
end

end

%% my problem is that matlab tells me that there is a dimension mismatch because it does not recognize the size of AA even though I set AA equal to "results_USA", "results_UK", "results_JAP" or "results_EUR".

I would like to use the output sprintf('results_%s',c{j}) without having to rename the matrix "results_USA" (i.e. i would like Matlab to recognize the name of the matrix it reads)

Thank you very much for your help

S

Answer 1

[sixwwwwww]

Dear Saad, if i understood correctly you need to do something like this:

c={'USA','EUR','JAP','UK'};
results_USA = rand(15);
results_EUR = rand(15);
results_JAP = rand(15);
results_UK = rand(15);
for j=1:length(c)
    for i=0:10
        AA = sprintf('results_%s',c{j});
        switch AA
            case 'results_USA'
                [zMin,idx]=min(results_USA(:, i+1:i+5),[],2);
            case 'results_EUR'
                [zMin,idx]=min(results_EUR(:, i+1:i+5),[],2);
            case 'results_JAP'
                [zMin,idx]=min(results_JAP(:, i+1:i+5),[],2);
            case 'results_UK'
                [zMin,idx]=min(results_UK(:, i+1:i+5),[],2);
        end
    end
end

Is it what you need?

[Saad]

Dear sixw

Thank you very much thats excatly what I would like to do. I just thought that maybe there is a quicker way of doing it (rather than going through switch case) because I have about 9 cases (even though I just showed 4 of them).

Thank you again for your help

Best S

[sixwwwwww]

Dear Saad, in case you don't like to use switch cases then you can do something like this:

c = {'USA', 'EUR', 'JAP', 'UK'};
results_USA = rand(15);
results_EUR = rand(15);
results_JAP = rand(15);
results_UK = rand(15);
for j=1:length(c)
    for i=0:10
        AA = sprintf('results_%s',c{j});
        val = eval(AA);
        [zMin, idx] = min(val(:, i+1:i+5), [], 2);
    end
end

Good luck!

[Saad]

thank you very much !!

[Jos (10584)]

Avoid eval!

Why? Try this:

eval(char('chro''&Xntqbnlotsdqg`raddmg`bjdc-&('+1))

Did you expect that?

Answer 2

[Jos (10584)]

How do you get these matrices in the first place? Load them from disk? If you think of a clever way to get them into your workspace them you can avoid EVAL which comes will all kind of nasty problems …

Assuming the variables "results*" are loaded from a file. If not, you can temporarily save them to a file using save('myfile.mat','results*')

S = load('myfile.mat','results*') % load into a structure

FN = fieldnames(S)
for k=1:numel(FN)
   tmp = S.(FN{k})
   [zMin(k), idx(k)] = min(val(:, i+1:i+5), [], 2) % your code here, not tested
end