Dynamic Variables in Loop

I need to import a lot of data from different files by specific criteria. Therefore i wrote an ImportLoop that reads all the data files.

Till now i have a problem generating different VariableNames in the Loop. The Variables shouldn't be named A1, A2,... like in the

eval( [ ['a' int2str(k) ] '=.....)

function. The VaribaleName MUST BE the name of the file i import in the loop, therefore i need the variable name to change dynamically inside:

path = 'C:\Users\(...)\*.txt';
files = dir(path);
names = {files.name};                        %Array with all the relevant FileNames

rootdir = "C:\Users\(...)\";

for k=1:numel(names)
   
    (...)
    
    [regexprep(extractBetween((names{k}),"A","."), '-', '')] = readtable(fullfile(rootdir, names{k}), opts);
     
end

I have read the whole despription why i shouldn't use dynamic variables but i havn't found any other solution that works cause the file names get imported randomly and therefore i need the FileName as VariableName to refer to it later in the code specifically.

So please don't just post me the Link, i have seen it 200 times so far.

Ty so much in advance.

[Stephen23]

Context of this question:

https://www.mathworks.com/matlabcentral/answers/640900-filepath-including-a-variable

"I have read the whole despription why i shouldn't use dynamic variables but i havn't found any other solution that works..."

Indexing works.

"... cause the file names get imported randomly..."

Have you tried using the answer you were given to your earlier question?:

https://www.mathworks.com/matlabcentral/answers/640785-import-all-files-of-one-folder-in-order

"The VaribaleName MUST BE the name of the file i import in the loop, therefore i need the variable name to change dynamically inside:"

I very much doubt that it "MUST BE" named the same, it is much easier to store meta-data (such as filenames) as data in their own right, and use indexing to store that data in a loop. Using indexing is also what that MATLAB documentation recommends:

https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html

Answer 1

[Ameer Hamza]

Now that you are already aware of the problem with using eval to create variable names dynamically, a better approach is to use cell arrays; however, if you want to link filenames to the data, then use a struct. For example,

path = 'C:\Users\(...)\*.txt';
files = dir(path);
data = struct();
for k=1:numel(files)
    opt = ..
    filename = fullfile(files(i).folder, files(i).name);
    variable_name = regexprep(extractBetween((names{k}),"A","."), '-', '');
    data.(variable_name) = readtable(filename, opts);
end

data is a struct that contains the same field name as the filenames.

Another solution is to use the file struct to save the data directly.

path = 'C:\Users\(...)\*.txt';
files = dir(path);
for k=1:numel(files)
    opt = ..
    filename = fullfile(files(i).folder, files(k).name);
    files(k).data = readtable(filename, opts);
end

[Stephen23]

The second option is much simpler, more efficient, and a better use of memory

@Ameer Hamza: the indexing needs to be corrected (you used both i and k)

[Ameer Hamza]

@Stephen, thanks for point out the issue with indexing.