Reading mat files with variables that have different names

Hi there,

I am trying to load a bunch of mat files, the contents of which are CELL variables. For example when I load a file named "part1_240_T_1200_sig_25.mat", I get a variable named new_X1 which is a cell of size 1 by 240.........I tried various things like calling it in a structure, loading it like new_X = load('part1_240_T_1200_sig_25.mat'), but I still cant automate the process. At the end, I woud like to load the files in a loop (which I have done) but also change the variable names dynamically as the loop goes through several mat files.

So, if I could get something like

for ii = 1:files_length
  eval(['load ' files(ii).name ])
  num = size(new_X*{"ii"}*,2); %......change the cell variable name with the loop index
end

Would num2str work?? Thanks

Answer 1

[Image Analyst]

Just do something like this:

for ii = 1:files_length
    % Get filename
    filename = fullfile(pwd, files(ii).name)
    % Load the file into a structure.
    storedStructure = load(filename);
    % Extract the new_X1 into a vector.  We expect that it's a scalar.
    % Otherwise use 
    %   new_X{loopIndex} = storedStructure.new_X1;
    % to put it into one cell of a cell array.
    new_X(loopIndex) = storedStructure.new_X1;
    % Now do something with new_X in this loop.
end

You're reading in the files incorrectly (by using eval). See the FAQ for some correct ways to read in the various files in a loop: http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F. While you're at it, read this FAQ entry also: http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

Answer 2

[Jan]

Avoid eval(). Whenever you think of using this evil function, I promise, that there is a better, nicer, faster and more reliable method. (Phew, the frequent readers of the forum know, that even I know one task, which can be solved by eval() only - beside the evalulation of symbolic expressions).

eval(['load ' files(ii).name ])

 ==>

load(files(ii).name);

But it is even better to catch the loaded values in a struct:

Data = load(files(ii).name);

[chane moges]

you answer is incorrect because it jump the sequence of the foor loop. So you correct it and post again.

[Image Analyst]

See my (Image Analyst) answer above. I added a bunch of comments that will hopefully explain it.

Answer 3

[TUSHAR ANDRIYAS]

Both methods work like a charm.....that is exactly wat I wanted.....Thanks guys