How do I obtain size data from multi loaded text files?

I'm loading up a pair of text files (from the working directory) containing numerical data with the following code;

files = dir('*.txt');
for i=1:length(files)
    eval(['load ' files(i).name ' -ascii']);

end

Is there a way to obtain the size dimensions (for each text file) using this approach within the for loop?

Answer 1

[dpb]

Well, I misspoke on eval; to use the command-line form the filename can't be in a variable so that's the only way to do it.

What you really likely ought to do is switch over to using the functional form for load and also assign the result to a variable so you know the name.

The problem is that when you use the default assignment as done here, load "poofs" the variable name from the file name base name into the workplace(). That's ok for interactive use but difficult to handle easily programmatically in a script or function as then the only way to get access to that variable is either thru *eval or, perhaps a named structure field.

The latter would be something like...

[~,fn]=fileparts(files(i).name);       % get the base name from the file name
s.(fn)=load(files(i).name,'-ascii');   % load a structure w/ field that name
[nr,nc]=size(s.(fn));                  % and find out how big 'tis

Other than that you're at the mercy of eval and that's no road down which to travel..

See the documentation on structures in the 'Data Types' section for more details on using the dynamic name fields. Basically, the deal is if enclose a field name in paren's, that causes the variable to be evaluated and the value thereof to be used as the field name. Same idea as building a string for eval but much less error-prone.

() Even that isn't strictly true always, depending on the file name. There are a bunch of exceptions for filenames that include numerics or other special symbols so that you can't always get the imported variable name at all easily programmatically. See the doc for *load for details, but it isn't pretty...

[Brad]

Had to use the load function as you suggested. Working with legacy code does have its occasional pit fall. Thanks for the input.

Answer 2

[dpb]

files = dir('*.txt');
for i=1:length(files)
  eval(['load ' files(i).name ' -ascii']);

No need for eval here, just write

load file(i).name '-ascii';

As to the question, depends on what you mean by size as to how.

files(i).bytes

contains the disk storage of the file, the size function returns the size of the arrays in Matlab storage. There's also

doc whos  % not optional parameters for various uses

I don't understand the question title of "multi-loaded" text files?

[Brad]

dpb, sorry about the confusion. I'm looking to obtain the number of columns and rows for each text file loaded by the load function.

And thanks for the heads up on eval.