Reading and storing data efficiently - from spreadsheet to cell array

Hello everybody,

I am wondering what is the most efficient way to read data from a spreadsheet file and store it in the most efficient data structure. The question is general, but I also provide the way I do to welcome any suggestion.

I read data from very long spreadsheet (hundred-of-thousands rows for each sheet), and I need to store only one column for each sheet.

for j = 1:12
        Data = readtable(filename, 'Sheet', j+1, 'ReadVariableNames', false);
        Data = table2array(Data(:,3));
        Data = rmmissing(Data);
        
        filenameOutput = [outputDir, indexName{i}, monthName{j}, '.mat'];
        save(filenameOutput, 'Data');
end

What is the most efficient way to do it?

And what about if I want to store the data in a cell format (that is, a N(i)x1 cell where N(i) is the variable length of each column)?

Thank you very much in advance