How to speed up saving data to .txt file?

Question

AStro 2021-9-2

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1445349-how-to-speed-up-saving-data-to-txt-file

编辑： Jan 2021-9-26

Hi,

I am working on large data - several hundered waveforems, each with sampling rate of 10e7. My goal is to save data in to the txt file. Currently I am using 'writematrix' and 'append' for including all the information I need. The part of my code looks as follow:

for i = 1:length(Signal)

writematrix('Sampling Rate [Hz]:',SaveFile,'WriteMode','append');

writematrix(SampRate,SaveFile,'WriteMode','append');

writematrix('Test Time [sec]:',SaveFile,'WriteMode','append');

writematrix(TestTime(i),SaveFile,'WriteMode','append');

writematrix('Amplitude [mV]:',SaveFile,'WriteMode','append');

writematrix(Signal{i},SaveFile,'Delimiter','space','WriteMode','append');

writematrix('',SaveFile,'WriteMode','append');

end

As for now, the procoess of saving the data take forever. Is there any way to speed it up?

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Answer 1

Jan 2021-9-2

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1445349-how-to-speed-up-saving-data-to-txt-file#answer_779574

编辑：Jan 2021-9-26

在 MATLAB Online 中打开

fopen, fprintf or even better fwrite is much faster than the very smart writematrix. Appending requires to open the file and searching the end. It is much faster to open the file once only and write the data directly.

fid = open(Savefile, 'W');
for i = 1:length(Signal)
    fprintf(fid, 'Sampling Rate [Hz]: %d\n', SampRate);
    fprintf(fid, 'Test Time [sec]: %g', TestTime(i));
    fprintf(fid, 'Amplitude [mV]:\n');
    fprintf(fid, '%g ', Signal{i});
    fprintf(fid, '\n');
end
fclose(fid);