Dynamic Drop Down Menu

Hi guys,

i have some data which i have read in to a table (using App Designer). It is possible to read in multiple files. The Data contains some general information in the header and then some force measurement signal. The signal is filtered and the maximum is shown in the table. So now i want to add a drop down menu to plot the graphs from the data. My Problem is that the number of graphs i want to plot depends on the number of files i've read in, so the number is changing. Im not sure how to solve this, so thanks for any help!

The Code i have to store the data in a table is:

 function EinlesenButtonPushed(app, event)
%Diese Funktion dient dem direkten Lesen der auf dem übergeben Pfad
%hinterlegten CSV-Datei. Diese Datei muss exakt der Formatierung der
%Dateien entsprechen die das Program "Power" des Diagnostikgerätes
%liefert. 

%Einlesen der Datei über den Umweg mit strings



% Öffnen eines Fensters zur Auswahl der zu öffnenden .csv Dateien.
[filename,pathname] = uigetfile('*.csv;','MultiSelect',"on");


for i = 1:length(filename)
    
    filepath=fullfile(pathname, filename);
    fid = fopen (filepath{i});
   

%[file,path]=uigetfile('*.csv');
A = textscan(fid, '%s%s%s%s%s%s%s%s%s%s%s%s%s','Delimiter',';'); 


%Umwandeln von Cell --> String
B=string([A{:}]);

%',' durch '.' ersetzen
B=replace(B,',', '.'); % ',' durch '.' ersetzen

% Aufteilen in Header und Messdaten
Daten(i).Header=B(1:30,:);
Daten(i).Messdaten=str2double(B(31:end,7));


end



for i = 1:length(filename)
    
%Uhrzeit / time
u= char(Daten(i).Header(12,1));
u1 = extractBetween(u,13,20 );
    
 

%Datum / date
d = char(Daten(i).Header(11,1));
d1 = extractBetween(d,11,20);

%Bein Seite / leg
be = char(Daten(i).Header(21,1));
if strlength(be) == 22
    be1 = extractBetween(be,10,14);
else
    be1 = extractBetween(be,10,15);
end

% Bewegung / 
b = char(Daten(i).Header(23,1));
if strlength(b) == 32
    b1 = extractBetween(b,13,21);
else
    b1 = extractBetween(b,13,19);
end

% Kraft Tiefpass Filter / lowpass filter
x = Daten(i).Messdaten;
windowsize = 5;
c = (1/windowsize)*ones(1,windowsize);
a = 1;
y = filter(c,a,x);
M =max(y);   

drop(i) = append(u1,' ',b1,' ',be1); 
% Einlesen der Daten in Tabelle
data(i,:) = [d1 u1 b1 be1 M drop(i)];
   
  
end

app.UITable.Data = data; 

        end

Answer 1

[Mario Malic]

Hello,

Variable filename contains list of all files you're analysing?

You need to generate the cell of character arrays for Items property like this

ddItems = cell(length(filename), 1)
for ii = 1 : 1 : length(ddItems)
    ddItems{ii} = sprintf('Data%d', ii);
end
app.DropDownMenu.Items = ddItems;
app.DropDownMenu.ItemsData = 1 : length(ddItems);

[JoKi]

Yes, "filename" contains the list of the files i want to analyse.

Generating the Items for the DropDown works with your code. Thanks alot!

I'm still a bit confused on how to access the Items now, to plot the Graph.

[Mario Malic]

Data that you use to plot is this?

data(i,:) = [d1 u1 b1 be1 M drop(i)];

I have added one more line in the above code related to ItemsData property. With it, your Value property will be numeric, you can use it to index into data and send the row into function for plotting.

[JoKi]

The Data (force measurement signal) i want to plot is stored here:

Daten(i).Messdaten=str2double(B(31:end,7));

and i want to plot the raw data and filtered Data (y) from here:

% Kraft Tiefpass Filter / lowpass filter
x = Daten(i).Messdaten;
windowsize = 5;
c = (1/windowsize)*ones(1,windowsize);
a = 1;
y = filter(c,a,x);
M =max(y);   

[Mario Malic]

Since, all of this is in for loop, you can set your y variable as a property of the app, so you can access it from anywhere within the app

x = Daten(i).Messdaten;
windowsize = 5;
c = (1/windowsize)*ones(1,windowsize);
a = 1;
app.y(i,:) = filter(c,a,x);

I do not know how does your app looks like, or how do you want to do the plotting, but you'll need to create a callback for the DropDownMenu component

function DropDownValueChanged(Source,Event)
    index = app.DropDownMenu.Value;
    plot(app.UIAxes, x,app.y(index,:)); % I am not sure what x is, if it's the first line from section above, then
                            % do the same as in y, make it x(i,:) and property of the app
end

Also, consider what happens when you change the dropdown value, do you want to add the data, or you want to plot only the selected one, you can use hold function to do it programmatically or change the settings in the UIAxes component.

hold(app.UIAxes, 'on') % example

[JoKi]

That helps, again thanks alot!