Looping through a cell with datasets

Hi everybody,

I have a question about looping through a cell with multiple dataset (1x9 cell with each cell being 19x19 double). I try to use the following script:

DataFiles = {dataset1, dataset2, dataset3};

for iity = 1:length(DataFiles) [row, col] = ind2sub(size(DataFiles(1,iity)), find(DataFiles(1,iity)>0.5)); sig_results = row; sig_results(:,2) = col;

    plot.cs = sig_results;
end

and I keep getting the following error:

Undefined function 'gt' for input arguments of type 'cell'.

Does anyone know what that means? And what seems to be the problem?

Best regards,

Christian

Answer 1

[Stephen23]

This error message is telling you that the function gt (which you use the alias of with ...>0.5 ) is not defined for cell array input values. The function gt requires numeric array inputs, which you have inside your cell array... the trick is to use the correct indexing to get the numeric arrays back out. The difference is in the braces/brackets:

DataFiles = {dataset1, dataset2, dataset3};

for iity = 1:length(DataFiles)
      [row, col] = ind2sub(size(DataFiles{iity}), find(DataFiles{iity}>0.5));
      sig_results(:,1) = row;
      sig_results(:,2) = col;
      plot.cs = sig_results;
end

In essence:

• Brackets () always refer to the elements of the array that they are indexing, so MATLAB returns an array of the same type as the array that you are indexing into.
• Braces {} can be used with cell arrays to return whatever is inside those cells of a cell array (referred to as "content indexing" in the documentation):

http://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

http://blogs.mathworks.com/loren/2006/06/21/cell-arrays-and-their-contents/

http://www.mathworks.com/help/matlab/ref/specialcharacters.html

[Eric]

Thank you very much Stephen.

Best regards,

Christian