Read a .mat file and write .csv without opening matlab

I would like to read a ".mat" file and write it out as ".csv" file without opening matlab.

Basically this:

M = dlmread('FileName.mat', '\t', 1, 0);
csvwrite('FileName.csv', M)

but then without opening matlab.

I'm using linux command line.

Thanks!

Answer 1

[Marc Jakobi]

You won't be able to run a Matlab-file without opening Matlab - unless you use another program that is compatible.

However, you could write a bash script that runs Matlab in a "hidden" mode:

#!/bin/bash
matlab -nodisplay -nodesktop -r "run /path_to_script/my_script.m"

P. S. I wouldn't recommend csvwrite. fprintf is a lot more flexible and faster.

fid = fopen('filename.csv','w');
fprintf(fid, formatSpec, data);
fclose(fid);

[Michael02139]

Hi Marc, thanks for your suggestions.

I'm starting with your suggestion to use fprintf and did this:

>> clear all
>> fid = fopen('FileName.mat','w');
fprintf(fid, formatSpec, data);
fclose(fid);

But I get this:

??? Undefined function or variable 'formatSpec'.

Any clue why? (your example text suggests opening a .csv file but I'm starting with .mat...)

thanks,

[Marc Jakobi]

You have to declare formatSpec as a variable first: According to the data you are writing to the CSV file.

Here's an example:

t = (0:900:31535100)';
P = rand(size(t));
fid = fopen('filename.csv','w');
formatSpec = '%d;%d\n';
fprintf(fid, formatSpec, [t, P]);
fclose(fid);

The formatSpec tells to write two columns of doubles (%d), delimeted with a semicolon. "\n" tells it to start a new line.

If you type

doc fprintf

in Matlab's command window, you will find a description and examples of how to use format operators.

[Walter Roberson]

You would want

fprintf(fid, formatSpec, [t, P].');

to write t and P into columns.

Answer 2

[Michael02139]

Thanks for all the tips. I'm just lost even after those tips. Which part of the tips are aimed at helping me to read in a *mat file? And which parts are aimed at writing out a *csv file?

[Marc Jakobi]

That was all about writing a CSV file. Loading a MAT file should be trivial:

 load('matFileName.mat')

If you don't know which variables are contained in the mat file, you can load it into a struct:

 S = load('matFileName.mat');
 varNames = fieldnames(S);

etc.

[Michael02139]

Thanks a lot for following up and responding again! That helped! I have it working.

Answer 3

[Walter Roberson]

Is the mat file text with tab delimiters or is it a binary file created by save()?

If it is text with tab delimiters then consider just using sed to change the tabs into comma

[Michael02139]

Got it! I like "sed" but it wasn't necessary this time.