Matlab save table with different file names in different files

Question

I'm trying to read different files (txt) using a datastore and readtable in order to parse them and write them into a .mat file. I'm using ds = datastore('*.txt').Files to get all the file names in a directory, then with a for loop I iterate through all the different files and I save them with different names. However when I import the file in matlab they have all the same table name (dat).

Here's the code:

ds = datastore('*.txt');
fnames = ds.Files;
l = length(fnames);

for i = 1:l
  dat = readtable(fnames{i}, 'Delimiter', '\t');
  dat.Properties.VariableNames(1:2) = {'rpm', 'p_coll'};
  dat = removevars(dat{i},20:width(dat));
  save([fnames{i} '.mat'],'dat');
end

I tried using an array of dat but it didn't work. Any ideas?

Why do you want different table names? What added benefit will you get with it? If there are 100 files, you want 100 different table variables? That'd be a very bad thing to do. — Sardar Usama

saastn saastn · Accepted Answer · 2019-11-13T23:35:03

As Sardar said there is no point in storing your data in L different variables. If you have to do so, there probably is a bigger problem in your program design. You'd better describe why you need that.

As an alternative, you can load those files in a single cell array:

L = 10;
for ii =1:L
   dat = 2*ii;
   fn = sprintf('dat%d.mat', ii);
   save(fn, 'dat');
end

dats = cell(L, 1);
for ii=1:L
    fn = sprintf('dat%d.mat', ii);
    load(fn);
    dats{ii} = dat;
end

Another option is to lad them in a struct:

dats = struct();
for ii=1:L
    fn = sprintf('dat%d.mat', ii);
    load(fn);
    dats.(sprintf('dat%d', ii)) = dat;
end

I do not see any advantage in this method compared to cell array, but it's kind of funny.

Finally, if you really have a reason to store data in multiple variables, you can use eval:

for ii =1:L
   dat = ii^2;
   eval(sprintf('dat%d=dat;', ii));
   fn = sprintf('dat%d.mat', ii);
   save(fn, sprintf('dat%d', ii));
end

for ii=1:L
    fn = sprintf('dat%d.mat', ii);
    load(fn);
end

Matlab save table with different file names in different files

1 Answers