MATLAB: Export data from CSV file as a vector.

csvexport

I am using an app to try different sources of energy, the problem is that the app exports the data in CSV format, even though it is okay to get the amplitude from the file, it isn't working to get the time. It is in HH:MM:SS.FFF, and I am not being able to export it to matlab as a variable (so I can plot time vs amplitude). I have to export the B column as a vector, any idea?

Best Answer

As I miss your sample of data, I have created one by myself (attached Data.csv). Below you can find a script that read this type of data.

fid = fopen('Data.csv');
if fid > 0
    data = textscan(fid,'%d %s %f %d','Delimiter',',');
    fclose(fid);
end
refTime=cellfun(@(x) datenum(x,'mm/dd/yyyy HH:MM:SS:FFF'),data(:,2),'UniformOutput',0);
plot(refTime{:},data{:,3})
datetick('x','mm/dd/yyyy HH:MM:SS:FFF');

data will be a cell array, with its second column containing all of the date strings of the format

'01/09/2014 15:27:18:322'

To convert this to number you use the datenum

Regards

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To combine DateTime and data, they both need to be cell arrays, because one of them contains strings. This will work to produce a combined array

combined = [DateTime, num2cell(data)];

However, that won't solve your problem, because you can't write a cell array with dlmwrite.

One possibility is to do something like the code below, using fprintf to do the tab-separated data. Note that this code uses the original numerical data matrix, and that you may need to fiddle with the format for the numbers to get the precision you need.

outfile = 'path/output.out';
header = { ...
    '        DateTime', ...
    'data1','data2','data3','data4', ...
    'data5','data6','data7','data8', ...
    'data9','data10','data11','data12'};
fid = fopen(outfile, 'w');
if fid == -1; error('Cannot open file: %s', outfile); end
fprintf(fid, '%10s\t', header{:});
fprintf(fid, '\n');
for ii = 1:size(data, 1)
    fprintf(fid, '%s\t', DateTime{ii});
    fprintf(fid, '%10.6g\t', data(ii,:));
    fprintf(fid, '\n');
end
fclose(fid);

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posix_timestamp = 1.524216883857000e+09;
datetime(posix_timestamp,'convertfrom','posixtime', 'Format', 'yyyy-MM-dd HH:mm:ss.SSS')

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