how to do correlation tests to a cell array

Hi,

I have a cell array with 24 cells. I am trying to write a correlation between the variables inside each cell. In each cell, there is a table with dimensions 20*20. How can I write efficiently a code to automate it? Right now, my for cycle returns me an error, so I am sure something must be changed/added.

for i=1:1:24
figure;
set(gcf,"Visible","on");
correlationP1= corr(mydada{1, i},"rows","pairwise","type","Pearson")
end

I thank you in advance,

Best regards

Answer 1

[Arjun]

Hi @Hugo,

I see that there is a cell array in which each entry is a 20x20 table and you want to do correlation test on these tables.

The “corr” function in MATLAB expects inputs to be matrices but, in the code, provided, a table is passed as an input argument to the “corr” function which might be the cause of the error you are facing. It is suggested to use “table2array” function of MATLAB to convert the table to array and then pass it to the “corr” function.

Please refer to the code below for better understanding:

% creating some random data in the same format 

mydata = cell(1, 24); 

for i = 1:24 

    randomData = rand(20, 20); 

    mydata{1, i} = array2table(randomData); 

end 

% calculation of correlation matrix 

for i = 1:24 

    currentTable = mydata{1, i}; 

    % Calculate the correlation matrix 

    correlationP1 = corr(table2array(currentTable), 'rows', 'pairwise', 'type', 'Pearson'); 

    % Display the correlation matrix as per need 

    figure; 

    imagesc(correlationP1);  

    colorbar;  

    title(['Correlation Matrix for Cell ', num2str(i)]); 

    xlabel('Variable Index'); 

    ylabel('Variable Index'); 

    set(gcf, 'Visible', 'on'); 

end 

Kindly go through the documentation of “corr” and “table2array” function for better understanding:

• corr:https://www.mathworks.com/help/releases/R2022a/stats/corr.html
• table2array: https://www.mathworks.com/help/releases/R2022a/matlab/ref/table2array.html

I hope this will help!