How do I get cd to work properly?

I want to create a code that will parse through 15 folders (X_1, X_2, X_3) and open a subfolder folder 'Y_*' in each of these fifteen folders and open one document in the directory (example: X_1/Y_1/*.coord) I can do this easily in the command window using cd and I am able to code a for loop that will parse through the main X folders but I cannot figure out a way to open a folder with only part of the string. All of the subfolders start with Y_ but end with different numbers. I want Matlab to open the folder regardless of what number it is and only examine 'Y_'

I have tried doing this but I always get an error. How do I write this?

cd X_1/Y_*

Error using cd
Unable to change current folder to '/users/mss.system.V2roDc/Y_*' (Name is nonexistent or not a folder).

Answer 1

[Steven Lord]

The cd function doesn't accept wildcards. You could use dir (which does) and iterate through the list of directories in its output. I would avoid actually using cd to change directory; instead use fullfile to assemble the path to the file and then pass that path into whatever file reader you're using.

d = fullfile(matlabroot, 'toolbox', 'matlab', 'general')

d = '/MATLAB/toolbox/matlab/general'

howManyFilesAndDirs = numel(dir(d))

howManyFilesAndDirs = 82

f = fullfile(d, 'bench.dat')

f = '/MATLAB/toolbox/matlab/general/bench.dat'

theText = fileread(f);
theLines = split(theText, newline);
theLines(1:5)

ans = 5×1 cell array
    {'MATLAB(R) Benchmark Data.'                                                                                       }
    {' '                                                                                                               }
    {'Copyright 1984-2022 The MathWorks(R), Inc.'                                                                      }
    {'                                                                    LU      FFT     ODE     Sparse   2-D     3-D'}
    {'Mac mini, macOS 10.15.7, Intel Core i7 @ 2.3 GHz                 1.6177  0.5956  0.7646  0.6468  0.8542  0.5738' }

[Abinand Rejimon]

This is really helpful! Thank you so much for your assistance.

Answer 2

[Image Analyst]

I agree with Steve and the FAQ:

https://matlab.fandom.com/wiki/FAQ#Where_did_my_file_go?_The_risks_of_using_the_cd_function.

Don't use cd. Use fullfile and possibly sprintf to build up your full file name (folder plus base file name plus extension).

[Abinand Rejimon]

Thank you! I will look into those functions.