How can I assign a variable to all the columns and all the rows of a matrix?

Asked by Mau Dudas on 23 Oct 2019

Latest activity Answered by Jos (10584) on 23 Oct 2019

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Got a 20x10 double matrix and I'd like to assign 'numsub' to the number of rows and 'numtrials' to the number of columns in the whole matrix so that I can use them as an index in a for loop for extracting values from certain subjects.

I will need to do something like this:

for i = 1:numsubs

disp(['sub' num2str(i)])

disp('Slow trial')

for j=1:numtrials

if RT(j,i)<=0.3

disp(['trial' num2str(j)])

end(x3)

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2 Answers

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Answer by Jos (10584) on 23 Oct 2019

Accepted Answer

Are you looking for the function SIZE?

data = rand(20,10) ;
[numsubs, numtrials] = size(data)

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Answer by Bob Nbob on 23 Oct 2019

You don't need to actually create a new variable for this, you can just use the results from size.

A = randi(100,20,10);
[r,c] = size(A); % Where r is the number of rows, and c is the number of columns
% You can also just put the function directly into your loop
for i = 1:size(A,1)
    ...
    for j = 1:size(A,2)
    ...
    end
end

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