Load file with changeable variable

Dear all,

I would like to load some .mat file in this way:

File1 = 'D:\prj\MyComp\name.mat';
File2 = 'D:\prj\MyComp\anothername.mat';
File3 = 'D:\prj\MyComp\anotherdifferentname.mat';

namesWork = who;
outStr = regexpi(namesWork,'File');
ind = ~cellfun('isempty',outStr);
ind = ind(ind==1);

for h = 1:length(ind)
     load(['File' num2str(h)])
     ...
end

But it returns this error message:

Error using load
Unable to read file 'File1'. No such file or directory.

Thanks in advance, JOE

[Stephen23]

What you are trying to do is load a file named 'File1', because that is the string that you are giving to load. To generate the value of the variable File1 you would have to evaluate the string. But that would be a bad way to write code: Slow, buggy, obfuscated, and really hard to debug:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Answer 1

[Stephen23]

Don't waste your life writing buggy code. Much simpler and much more reliable would be to use a cell array:

C = {...
   'D:\prj\MyComp\name.mat',...
   'D:\prj\MyComp\anothername.mat',...
   'D:\prj\MyComp\anotherdifferentname.mat'};
for k = 1:numel(C)
    S = load(C{K});
    ...
end

By choosing to use a simple, easy-to-understand way of writing code (i.e. a cell array) I solved your task in just a few efficient lines of code. This is explained very well in the documentation and on this forum:

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

https://www.mathworks.com/matlabcentral/answers/57446-faq-how-can-i-process-a-sequence-of-files

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Answer 2

[Geoff Hayes]

J - when you call

 load(['File' num2str(h)])

you end up trying to load a file whose name is (if h is one) File1. This is a string and not the variable that you had previously initialized and so the error message makes sense.

What I would do is to add all of your file names to a cell array and then iterate over each element in the array. As each element is a valid file name, then you should be able to load the file. For example,

 myFiles = cell(3,1);
 myFiles{1} = 'D:\prj\MyComp\name.mat';
 myFiles{2} = 'D:\prj\MyComp\anothername.mat';
 myFiles{3} = 'D:\prj\MyComp\anotherdifferentname.mat';

and then

 for k=1:length(myFiles)
     X = load(myFiles{k});
     % do something
 end