How can I create paths relative to a specific folder to facilitate moving project folders to other locations?

Hello everyone!

I would like to find a better way to use paths in Matlab. I often use Matlab scripts to postprocess data, for example by going through many text files and reading their content into Matlab for further analysis. The "problem" I have is that when I have my files in very nested locations and I move the folder containing the files and the script, I have to re-specified the whole path again in the script. I would like to specify the location of the txt files to read relative to the folder that contains the script. How can I achieve this?

Example of project folder:

C:\Users\myusername\Documents\subfolder1\subfolder2\subfolder3\myProject_Folder

'myProject_Folder' contains my txt files in a subfolder:

C:\Users\myusername\Documents\subfolder1\subfolder2\subfolder3\myProject_Folder\txt_files_Folder

and a script, for example

script.m

In script.m I have these lines for example:

outputDir = 'C:\Users\myusername\Documents\subfolder1\subfolder2\subfolder3\myProject_Folder'; %same as Project Folder
txt_files_path = ' C:\Users\myusername\Documents\subfolder1\subfolder2\subfolder3\myProject_Folder\txt_files_Folder'

I would like to have \myProject_Folder as the root folder, so that when I move myProject_Folder and its subfolders to another computer I do not have reenter all the paths again in script.m.

Thanks in advance!

Best regards,

Adriel Perez

Answer 1

[David Goodmanson]

Hi Adriel,

Here's one approach, concatenation

% give the path a short name, the idea is on the computer you only have to specify this once

outD = 'C:\Users\myusername\Documents\subfolder1\subfolder2\subfolder3\myProject_Folder';

% then
txt_files_path = [outD, '\txt_files_Folder']
txt_files_path2 = [outD, '\new_txt_files_Folder2']
% and so forth.

You can also make use of the cd function. In my case

Cpath = cd

Cpath = 'c:\users\dave\tech\matlab'

which is a string you can concatenate with something else as with outD, or lop part of it off.

If you have a home base and want to go to the end of some path and temporarily make it the local directory you can do

home_path = cd        % save your location
% and
cd(txt_files_path)

Then you can read files in and out locally with no path prefix. After that, cd(home_path) takes you back from whence you came.

Lots of possibilities, this is kind of the 'original' way and if there are more sophisticated ways I imagine others will weigh in.

[Image Analyst]

More robust would be to use the fullfile() function instead of []:

txt_files_path  = fullfile(outD, 'txt_files_Folder')
txt_files_path2 = fullfile(outD, 'new_txt_files_Folder2')

[Stephen23]

Note that cd is slow and make debugging harder: it is better to use absolute or relative filenames:

https://www.mathworks.com/help/matlab/matlab_env/specify-file-names.html

And as Image Analyst already pointed out, use fullfile rather than concatenating.

[Adriel Perez Tellez]

Thanks everyone!

@ David Goodmanson Thanks! I still need to specify the full path at least once, as you did with

outD

Ideally I would need a line of code in my script that would retrieve the full path to the script. I did not know about cd, thanks!

[Adriel Perez Tellez]

Hi again! Just wanted to share this. This code:

[outD, ~  , ~] = fileparts(which(mfilename))

gives me the folder containing my script

Answer 2

[Adriel Perez Tellez]

I will be using

fullfile

from now on, thanks!

Answer 3

[Sean de Wolski]

mfilename('fullpath'), fullfile, fileparts, pwd are my best friends for this type of work.