MATLAB export multiple .csv files at one time

Question

I have a matrix where I need to export each column into a separate .csv file. I know the number of columns and I can achieve my desired result if I specifically select one column to export. I would do this by:

dlmwrite('1.csv',data(:,1), 'precision', 9)

Therefore if I want column 2 I would change the variable to data (:,2) and save this as 2.csv .

So I want a loop that will do all this automatically. I have tried

for i=1:Number_of_Columns
    dlmwrite('(i).csv',csv_data(:,(i)), 'precision', 9)
end

which clearly won't work but I am unsure how to do it.

Any help or advice would be much appreciated

Answer 1

Your problem is the filename. If you put i between quotes it will be taken as character instead of a variable. (In your case your filename will always be "(i).csv")

You can concatenate strings using [ ], and since i is an integer you have to convert it to string using num2str()

Try:

for i=1:Number_of_Columns
    dlmwrite([num2str(i) '.csv'], csv_data(:,i), 'precision', 9)
end

PD: Since you are storing each column (not each row) in a file, I'm not sure if you want a file where each element is in a separate line, or if you want the column to be stored as a row and separated by commas.

If you want the latter, transpose your column:

dlmwrite([num2str(i) '.csv'], csv_data(:,i).', 'precision', 9)

Note that the transpose operator is .' instead of the complex conjugate ' (this is a common misuse since the results are the same as long as you only use real numbers)