Writing in a listbox

I am trying to write a list in a listbox.

code:

function listbox1_Callback(hObject, eventdata, handles)
% hObject    handle to listbox1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: contents = cellstr(get(hObject,'String')) returns listbox1 contents as cell array
%        contents{get(hObject,'Value')} returns selected item from listbox1
error = getappdata(0, 'error_norm');
rows = size(error,1);

for i = 1:rows
  set(handles.listbox1,'string',strcat('filt_',num2str(i)));
  for j = 1:length(error)
      set(handles.listbox1,'string',strcat('sig_',num2str(i),'_',num2str(j)));
      for k = 1:length(error{j}.main)
          set(handles.listbox1,'string',strcat('seg_',num2str(i),'_',num2str(j),'_',num2str(k)));
      end
  end
end

where 'error' is a array of structure . i want to write on list box something like this:

filt_1
sig_1_1
seg_1_1_1
seg_1_1_2
sig_1_2
seg_1_2_1
seg_1_2_2

but apparently, 'set' function overwrites, so all i am getting is only 1 element and the last element.

How do i make it write all of it, any help will be appreciated.

Answer 1

[Walter Roberson]

You need to create a cell array of strings first, and then set() that cell array as the String property of the handle.

[JA]

problem with creating the cell array of strings was the indices, it was very confusing. Can you please demonstarte how to do that. with the for loop structure i have shown

[JA]

I tried something like this:

error = getappdata(0, 'error_norm'); rows = size(error,1);

for i = 1:length(rows)
    filt{i} = ['filt_', num2str(i)];
    for j = 1:length(error)
        filt{i,i+j} = ['signal_',num2str(i),'_',num2str(j)]
        for k = 1:length(error{j}.main)
            filt{i,i+j,i+j+k} = ['segment_',num2str(i),'_',num2str(j),'_',num2str(k)]
        end
    end
end
set(handles.listbox1,'string',filt);

still doesn't work. any help will be appriciated

[Walter Roberson]

idx = 0;

for i = 1:length(rows)
    idx = idx + 1;
    filt{idx} = ['filt_', num2str(i)];
    for j = 1:length(error)
        idx = idx + 1;
        filt{idx} = ['signal_',num2str(i),'_',num2str(j)];
        for k = 1:length(error{j}.main)
            idx = idx + 1;
            filt{idx} = ['segment_',num2str(i),'_',num2str(j),'_',num2str(k)];
        end
    end
end
set(handles.listbox1, 'string', filt);

But I recommend you switch to using sprintf()

idx = 0;

for i = 1:length(rows)
    idx = idx + 1;
    filt{idx} = sprintf('filt_%d', i);
    for j = 1:length(error)
        idx = idx + 1;
        filt{idx} = sprintf('signal_%d_%d', i, j);
        for k = 1:length(error{j}.main)
            idx = idx + 1;
            filt{idx} = sprintf('segment_%d_%d_%d', i, j, k);
        end
    end
end
set(handles.listbox1, 'string', filt);

[JA]

thanks! you're a hero

[JA]

Just 1 question, I have wrote this code on 'listbox1' callback, so this only appears when i click on the listbox. where should i write the code so that the list appears when the GUI is opened?

[Walter Roberson]

Put it in your OpenFcn for the figure, provided that you know the rows and error arrays by the time you open the GUI.

Alternately, if length(rows) and length(error) and all the length(error{j}.main) cannot change, you could run that code to set the listbox properties before you save the GUIDE figure, and then you would not need to set them dynamically.

[JA]

Thanks, it worked. Just 1 more question. how to get the string of selected item in the listbox. when i write'get(handles.listbox1,'string')'. i get all items in the listbox and when i do 'get(handles.listbox1, 'Value')' i am getting 1x1 double 1. not the selected item name, but just 1. how do i get the selected item name as a string.

[Walter Roberson]

all_choices = get(hObject, 'String');
choice_idx = get(hObject, 'Value');
chosen_string = all_choices{choice_idx};

[JA]

You are my savior today.