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

Question

Raguram N 2017-6-23

4
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https://ww2.mathworks.cn/matlabcentral/answers/346058-how-to-write-a-mixed-data-text-and-number-in-a-csv-file

评论： dpb 2021-10-10

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 2017-6-23

How are the data stored in variables in memory?

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Answer 1

per isakson 2017-6-23

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https://ww2.mathworks.cn/matlabcentral/answers/346058-how-to-write-a-mixed-data-text-and-number-in-a-csv-file#answer_271767

编辑：per isakson 2017-6-23

在 MATLAB Online 中打开

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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Answer 2

dpb 2017-6-23

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/346058-how-to-write-a-mixed-data-text-and-number-in-a-csv-file#answer_271766

在 MATLAB Online 中打开

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 2019-2-20

编辑：Daelyn Greene 2019-2-20

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 2019-2-21

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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