MATLAB Answers


How to write txt file contain double array and text header?

Asked by Danupon Subanapong on 23 Mar 2019
Latest activity Commented on by Danupon Subanapong on 23 Mar 2019
I have to write a text file containg array and text header. My numeric array is in size of 33731x48. I knew that I can use fprint to output text file, but my double array has too many columns. I don't know how to set up the formatting operator for all double array element. I want all element to be floating point number (%f). I am thinking about writing 48 %f inside fprintf function For example,
fprintf(fid, '%f %f %f... %f r\n', array);
and there are 48 %f inside fprintf function, but it should be better way. So, could you please help me giving some advice?


Could you upload your numeric matrix as .mat file?
Hello Ravi,
Thank you so much for your reply. I attached part of numeric array. I cannot upload all data since it exceeds 5MB. But I think it is fine. Please check it.

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1 Answer

Answer by Rik
on 23 Mar 2019
Edited by Rik
on 23 Mar 2019
 Accepted Answer

You can use repmat or sprintf to construct the FormatSpec.
fid=fopen('test.txt','wt');%opening with the t flag auto-converts \n to \r\n on Windows
fprintf(fid,'some cool header text\n');
FormatSpec=[repmat('%f ',1,size(array,2)) 'r\n'];%or should that have been \r\n instead?
fprintf(fid,FormatSpec, array);


I have got an error as below.
Error using horzcat
Dimensions of arrays being concatenated are not consistent.
The error is caused by this line.
FormatSpec=[repmat('%f ',size(array,2)) 'r\n'];%or should that have been \r\n instead?
I have checked it repmat('%f ',size(array,2)) works fine, but when combining with 'r\n' string it gets error.
Sorry, that was a typo. The repmat function call now creates a 2D array, instead of a vector, I'll edit my code to fix this.
Thank you so much!! It really helps.

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