Convert from datenum to yymmddHHMMSS

I have a large list of dates which I previously converted from yymmddhhmmss format to datenum format using

dateFormat='yymmddHHMMSS';
date=datenum(date,dateFormat);   

Now, at the end of a lot of processing, I'd like to reverse this process, to make presentation of my data more readable.

I have tried this:

formatOut='yymmddHHMMSS'; %convert datenum back to original filename format
short_files=datestr(short_files, formatOut); 

out=('short_files.csv'); %.csv filename with serialNo 
[~,fnm,ext]=fileparts(out);
out = sprintf('%s_%d%s',fnm,serialNo,ext);

dlmwrite(fullfile(path,out),short_files,'delimiter',''); 

and while this works in my list of variables, when I export to .csv, the values I get look like this:

1.90704E+11 .

Answer 1

[Walter Roberson]

dlmwrite() assumes that the inputs are numeric unless you specify the 'precision' option with a format code such as '%s'

You should

outfile = fullfile(OutputDirectoryName, out);
fid = fopen(outfile, 'wt');
for K = 1 : size(short_files,1)
    fprintf(fid, '%s\n', short_files(K,:));
end
fclose(fid)

Or you should skip the problem by using datetime objects and tables and writetable()

[Louise Wilson]

Thank you Walter for getting back. I don't quite understand, where is it that you specify the code for dlmwrite?

I was wondering how to convert from datenum to datetime so that I can use writetable?

[Walter Roberson]

It appears I was mistaken about dlmwrite() details. What happens if you try

out = datestr(700000+rand(10,1)*1000,'yymmddHHMMSS');
dlmwrite('test.csv', out, 'delimiter', '')

When I try this, I get the expected output.

Note though that this would not be usable to also write any other non-character output at the same time.

[Louise Wilson]

Hi Walter, I figured it out by just doing this:

formatOut='yymmddHHMMSS';
short_files=datestr(short_files_list, formatOut);

out=('short_files.csv'); %.csv filename with serialNo 
[~,fnm,ext]=fileparts(out);
out = sprintf('%s_%d%s',fnm,serialNo,ext);

dlmwrite(fullfile(folder,out),short_files,'delimiter',''); %write output to separate .csv

...this converts the filename back to the format I am interested in and writes to the csv all good.

Thanks for your help