About function in methods of a class

Hi guys, I'm doing a project.

To use function in methods of one of my class I defined, I made this one :

function [y, Fs] = getRandomMusic(feeling)
    path_name = strcat('C:\Users\Jack\Desktop\music','\',feeling);
    music_lists = dir(path_name);
    music_number = length(music_lists);
    
    ran_music_number = randi(music_number);
    while ran_music_number < 3
        ran_music_number = randi(music_number);
    end
    
    file_name = strcat(path_name,'\',music_lists(ran_music_number).name);
    [y, Fs] = Audioread(file_name, native);
end

This is the function when input "feeling", then it returns [y, Fs] of randomly selected from the "feeling" folder.

But when I rud the main MATALB file to use this function, it makes an error messgae like this :

Check the function 'getRandomMusic' for missing arguments or invalid argument data types. (It's not official message cuz my mother tongue isn't english)

Can anyone suggest something to me?

Thanks!

[per isakson]

I don't get the big picture. What does "use function in methods" mean?

Use the function fullfile() instead of strcat() to create full file specifications.

Replace Audioread() by audioread()

[Tony Kaywood]

Thanks for the comment. I meant to say I had defined function in class file and there had some proplem when I called the function in another MATLAB file.

[per isakson]

"defined function in class file" There is a problem with nomenclature. In Matlab methods of classes are defined with the keyword, function.

classdef MyClass
    methods
        function [y,Fs] = getRandomMusic( obj, feeling )
        end
    end
end

In this basic case you have to take the instance variable, obj, as the first input argument.

Answer 1

[Steven Lord]

If getRandomMusic is a non-Static method of a class (which I'll call iPod just to have some way to refer to the class) then at least one of the inputs to getRandomMusic must be an iPod object. If you try to call it without at least one iPod object, MATLAB won't know to what getRandomMusic refers.

You could make feeling an iPod object, or you could have getRandomMusic accept two inputs (one an iPod object and one a char vector or string, based on the context.)

p = iPod;
[y, Fs] = getRandomMusic(p, 'happy');

Other options include making getRandomMusic a Static method of the iPod class, in which case you would need to call it using the class name:

[y, Fs] = iPod.getRandomMusic('happy');

or turning getRandomMusic into a function rather than a method. If it's only intended to be called from within methods of the iPod class it could be a class-related function defined in the classdef file but after the end keyword associated with the classdef keyword. If you intend it to be called from outside the class as well I'd define it as a regular function in its own file.