listbox selection, push button and which error..

Hey all,

I have a gui listbox that loads only wav file names into it on the gui opening. From there a push button takes the selection and audioreads the chosen file. Well it should do but with the following code, it errors out. See error below below..

% **********************************************
% FORM LOAD AND OPEN..
% **********************************************
% --- Executes just before EPM_gui_form is made visible.
function EPM_gui_form_OpeningFcn(hObject, eventdata, handles, varargin)
% Choose default command line output for EPM_gui_form
handles.output = hObject;
% Update handles structure
guidata(hObject, handles);

% DECLARE GLOBAL VARIABLES..
%global isMELODY; % DEFINE isMELODY AS CATCH FOR IF MELODY IS CREATED OR NOT..
%isMELODY = 0; % SET isMELODY TO 0 (NOT CREATED YET)..
global NoteX; % DECLARE VARIABLE FOR NOTE LETTER..
global FreqX; % DECLARE VARIABLE FOR NOTE FREQUENCY..
global FreqBPFTStop1; % DECLARE VARIABLE FOR BP FILTER STOPBAND 1..
global FreqBPFTPass1; % DECLARE VARIABLE FOR BP FILTER PASSBAND 1..
global FreqBPFTPass2; % DECLARE VARIABLE FOR BP FILTER PASSBAND 2..
global FreqBPFTStop2; % DECLARE VARIABLE FOR BP FILTER STOPBAND 2..
global FreqBSFTStop1; % DECLARE VARIABLE FOR BS FILTER STOPBAND 1..
global FreqBSFTPass1; % DECLARE VARIABLE FOR BS FILTER PASSBAND 1..
global FreqBSFTPass2; % DECLARE VARIABLE FOR BS FILTER PASSBAND 2..
global FreqBSFTStop2; % DECLARE VARIABLE FOR BS FILTER STOPBAND 2..
global d; % DECLARE VARIABLE FOR DIRECTORY..
global strLOAD; % DECLARE VARIABLE FOR FILENAMES.. 

% LOAD WAV FILES INTO LISTBOX..
d = dir('*.wav');  % Select Only ‘.wav’ Files
strLOAD = {d.name};
set(handles.listFILEwav,'String',strLOAD); %set string
% **********************************************

% **********************************************
% FORM OUTPUT..
% **********************************************
% --- Outputs from this function are returned to the command line.
function varargout = EPM_gui_form_OutputFcn(hObject, eventdata, handles) 
varargout{1} = handles.output;
% **********************************************

% **********************************************
% LOAD WAV..
% **********************************************
% --- Executes on button press in btLOAD.
function btLOAD_Callback(hObject, eventdata, handles)
global strLOAD; % DECLARE VARIABLE FOR FILENAMES.. 
wav_name = strLOAD;  % FILE NAME OF THE SELECTED PATH..
wav_path = which(wav_name);  % PATH OF THE SELECTED FILE..   

msgbox({'Wav: ',wav_name});

% OPEN AND READ THE DESIRED AUDIO WAV FILE..
[Wave,Fs] = audioread(wav_name);
soundsc(Wave, Fs);
% **********************************************

Here's the error:

Error using which
Argument must contain a string.

Error in EPM_gui_form>btLOAD_Callback (line 89)
wav_path = which(wav_name);  % Path Of Selected File

Error in gui_mainfcn (line 95)
        feval(varargin{:});

Error in EPM_gui_form (line 34)
    gui_mainfcn(gui_State, varargin{:});

Error in
matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)EPM_gui_form('btLOAD_Callback',hObject,eventdata,guidata(hObject)) 
Error while evaluating UIControl Callback

It says which needs to be a string but I would have thought that the dir kicks out a string of the files and populating the listbox with these strings as strLOAD, so therefore the code in the btLOAD_Callback should be a string? Or am i missing something?

Thanks.

Paul..

Answer 1

[Walter Roberson]

You are incorrect. The pushbutton ignores the listbox rather than taking the selection. Instead the pushbutton is taking the result of

d = dir('*.wav');  % Select Only ‘.wav’ Files
strLOAD = {d.name};

which is creating strLOAD as a cell array of strings rather than as a single string. You cannot which() a cell array of strings.

Using which() is a waste of time. You already know which directory they are in: they are in the directory that you did the dir('*.wav') inside. You can find out which directory you are in by using the call cd()

[Edmund Paul Malinowski]

Hey Walter,

Thanks for your reply. Yeah i read up on that. You'e right, the which command is pointless here. What i need is to pass the actual string of the chosen file in the listbox to the push button callback.

As using:

strLIST = get(hObject, 'String');

...gets the entire string array of the listbox and:

valLIST = get(hObject,'Value');

...gets the index obviously.

So how do i get the individual string that's chosen?

[Walter Roberson]

strLIST{valLIST}

[Edmund Paul Malinowski]

That got it :) thanks Walter