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How to write a mixed data (text and number) in a CSV file ?

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Raguram N
Raguram N 23 Jun 2017
답변: breathi 13 Dec 2019
I need to write a CSV file with text matrix in the first column and numbers matrix in the second column.
Example
matrix1 = {'water';'space';'fire'};
matrix2 = [100;200;300];
CSV file output as:
water,100
space,200
fire,300
Please provide me some direction to solve this problem. Please let me know for further information.
Thanks in advance, Ram

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per isakson
per isakson 23 Jun 2017
How are the data stored in variables in memory?

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답변(3개)

per isakson
per isakson 23 Jun 2017
편집: per isakson 23 Jun 2017
matrix1 = {'water';'space';'fire'};
matrix2 = [100;200;300];
fid = fopen( 'matrix.csv', 'w' );
for jj = 1 : length( matrix1 )
fprintf( fid, '%s,%d\n', matrix1{jj}, matrix2(jj) );
end
fclose( fid );
The format specifier %d assumes that matrix2 contains whole numbers, if not use %f

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dpb
dpb 23 Jun 2017
It seems like "'round Robin Hood's barn!" way to get there, but believe it or not,
fname='yourfile.csv';
writetable(cell2table([matrix1 num2cell(matrix2),fname,'writevariablenames',0)
is about as simple a way to do the job as there is.
The mid-level routines such as dlmwrite are simply unable to deal with the cellstr content while the low-level routine fprintf requires you to handle all the formatting and loop writing each record one-at-a-time to build the file. Not terribly difficult but tedious at best and seems much harder than it actually is when just getting started. TMW has done quite a bit on the input side; the output side is lagging although writetable is a start, Matlab needs better high-level tools for outputting data that is something other than just double arrays.

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Daelyn Greene
Daelyn Greene 20 Feb 2019
Is there a way to append new data to the end of an existing file using this? I am wanting to do something exactly like this, only with data being gradually input over time from selections in a UI.
dpb
dpb 21 Feb 2019
With this workaround, no; not directly to text file; writetable has no "append" option.
You could take the additional circuitious route of writing to a spreadsheet and then saving it, but that would require keeping track of the number of lines written to compute the right range to specify so, while possible, not of more than theoretical interest.
In that case, there are any number of posts/answers but Per's solution below is the trick except you must open the file with the 'append' flag of 'a' or 'a+' instead of 'w' to not overwrite existing data in the file.

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breathi
breathi 13 Dec 2019
Since R2019a,
writecell
is doing this perfectly for a cell array.

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