How to load *.mat file from each directories in new script?

I have 15 directories and in each directories, I have minimum 8 sub-directories( varies in each directories). For each directory, I have .mat file that I have saved for future use. Now, I want to develop a new script which load .mat file in each directory? How do I load .mat file from each directory? The name of .mat file is same for each directory. Any idea is highly appreciated. Thank you

[Andrew Newell]

Depends what you want to do with each .mat file. Do you process its contents and then overwrite it with the next .mat file? Do you have a .mat file in each sub-directory? And do you know in advance what the directories are, or will you need to determine that automatically?

[sam moor]

No I don't want to overwrite each .mat file rather load each .mat file from each directory and save each .mat file in matrix form

[Andrew Newell]

Fortunately, the code I provided below is compatible with that.

Answer 1

[Image Analyst]

See attached demo. If you have R2016b or later, use that one, which has enhanced capabilities for dir() that mean you don't need to call genpath() anymore.

[Andrew Newell]

Fancy! Is this in the FEX?

[Image Analyst]

No. Currently I have about 250 demo scripts. I just put the most "important" ones in my File Exchange. I'm afraid if I put up every little demo that the important ones might get lost in the larger group of them. Every once in a while I think of zipping them all up into something like a "grab bag of Image Processing Demos" and upload that, but I haven't yet.

Answer 2

[Andrew Newell]

Here is a solution that assumes there is one of these .mat files in every subdirectory of each of the 15 directories. Let's also assume that all 15 directories are all in the same directory, and fullrootdirectoryname is its name. Also, there are no other directories in that space. Then you can do the following to visit each directory and load the file:

C = strsplit(genpath(fullrootdirectoryname),':'); % Generate a list of folders
startingFolder = pwd;
for ii=1:length(C)
  cd(C{ii})
  load yourFilename.mat
end
cd(startingFolder)

The business with startingFolder makes sure you end up back where you started, and not in some unexpected place. If any of the above assumptions are not met, this code will need to be modified.

[sam moor]

Hi Andrew, your code gave me error as: Error using cd Cannot CD to E (Name is nonexistent or not a directory).

Error in Untitled2 (line 4) cd(C{ii})

[Andrew Newell]

A thought just occurred to me - are you on a PC? If so, I'll need to see what the output looks like when you run

genpath(fullrootdirectoryname)

I don't have a PC, so I'll have to do some reverse engineering.

[Andrew Newell]

Try replacing the top line in my code by the following:

pp = genpath(fullrootdirectoryname);
searchstr = [':(?=.:',filesep,')'];
C = regexp(pp,searchstr,'split');

[sam moor]

still getting error

[Andrew Newell]

O.k., what platform are you running MATLAB on? And can you show me what the result of genpath is?

[Andrew Newell]

Fine, but that isn't the information I need.

[Walter Roberson]

The use of "File folder" suggests MS Windows to me.

[Andrew Newell]

As does the error "Cannot CD to E". But I don't know what the output of genpath looks like on Windows. I thought I could guess, but apparently not.

[sam moor]

when i only used genpath, it lists all the files and folders as a struct. but it gives error while trying to run all your scripts.

[sam moor]

I am using window platform

[Andrew Newell]

Really, a struct? That is totally unlike the expected behavior (see genpath). Two more questions:

1. Which version of MATLAB do you have?
2. Try running

which genpath -all

and please show me what you get.

[sam moor]

when I type which genpath -all it gives C:\Program Files\MATLAB\R2016a\toolbox\matlab\general\genpath.m

[Andrew Newell]

That also answers the question about the MATLAB version. So its output should be a string. Can you please show me the string?