MATLAB: Appdesigner create loop for drop down Items

app designerdrop downlookup tableplottingwhile loop

Hello,
I am using app designer to import data from a csv file an plot curves, based on the data from the file, in UIAxes. I'd like to implemet the function to change the colour of each curve. Therfore, I use a drop down field, filled with 8 different colours. These colours are defined in the private properties area (RGB values).
        LightBlue = [0.3010 0.7450 0.9330];
        DarkBlue = [0 0.4470 0.7410];
        LightRed = [0.8500 0.3250 0.0980];
        DarkRed = [0.6350 0.0780 0.1840];
        Yellow = [0.9290 0.6940 0.1250];
        Purple = [0.4940 0.1840 0.5560];
        Green = [0.4660 0.6740 0.1880];
        Black = [0 0 0];
After changing the dropdownfield-value, the user has to confirm his changes. To use a short code, I want to create a while-loop:
        A = [app.ColourDropDown_1.Value app.ColourDropDown_2.Value app.ColourDropDown_3.Value app.ColourDropDown_4.Value app.ColourDropDown_5.Value app.ColourDropDown_6.Value app.ColourDropDown_7.Value app.ColourDropDown_7.Value];
            B = [app.ColourCurve1 app.ColourCurve2 app.ColourCurve3 app.ColourCurve4 app.ColourCurve5 app.ColourCurve6 app.ColourCurve7 app.ColourCurve8];
            C = 1;
            
            while C<9
                switch A(1,C)
                    case 'Light blue'
                        B(1,C) = app.LightBlue;
                    case 'Dark blue'
                        B(1,C) = app.DarkBlue;
                    case 'Light Red'
                        B(1,C) = app.LightRed;
                    case 'Dark Red'
                        B(1,C) = app.DarkRed;
                    case 'Yellow'
                        B(1,C) = app.Yellow;
                    case 'Purple'
                        B(1,C) = app.Purple;
                    case 'Green'
                        B(1,C) = app.Green;
                    case 'Black'
                        B(1,C) = app.Black;
                end
                C = C+1;
            end
In the first iteration, the code should take the first value of matrix A (drop down field value). Then, it should take the first value from matrix B and allocate the colour-value.
Does anyone know a way to do that? I know the problem in my code, but is there another way than do the switch-case code for every chanel?
Thank you very much!

Best Answer

See inline comments for instructions
Option 1) Switch case
A = [app.ColourDropDown_1 app.ColourDropDown_2 app.ColourDropDown_3 ...
    app.ColourDropDown_4 app.ColourDropDown_5 app.ColourDropDown_6 ...
    app.ColourDropDown_7 app.ColourDropDown_7]; % These are handles now; ".Value" removed.
B = [app.ColourCurve1 app.ColourCurve2 app.ColourCurve3 ...
    app.ColourCurve4 app.ColourCurve5 app.ColourCurve6 ...
    app.ColourCurve7 app.ColourCurve8];
colors = nan(numel(B,3)); % Preallocate color matrix
for i = 1:numel(B) % use a for loop instead of a while loop.
    switch lower(A(C).Value) % Assumes the Value properties in A return strings/char-vectors; lower() used to avoid problem with case mismatch
        case lower('Light blue') % lower() used to avoid problems with case mismatch
            colors(i,:) = app.LightBlue; % store 1x3 color vector
        case lower('Dark blue')
            colors(i,:) = app.DarkBlue;
        case lower('Light Red')
            colors(i,:) = app.LightRed;
        case lower('Dark Red')
            colors(i,:) = app.DarkRed;
        case lower('Yellow')
            colors(i,:) = app.Yellow;
        case lower('Purple')
            colors(i,:) = app.Purple;
        case lower('Green')
            colors(i,:) = app.Green;
        case lower('Black')
            colors(i,:) = app.Black;
        otherwise % If no cases are matched, assign black.  
            colors(i,:) = app.Black;
            % error('Case not recognized.')  % or you can throw an error
    end
end
set(B, {'Color'}, mat2cell(colors,ones(numel(B),1),3)) % assign colors to all lines
Option 2) lookup table
Another cleaner way for you to do this would be to use a lookup table; no loops needed.
% General idea... not tested
colorNames = get(A,'Value'); % cell array of color names in order of A
% Look up color values
colorKey = {'LightBlue', [0.3010 0.7450 0.9330];
        'DarkBlue', [0 0.4470 0.7410];
        'LightRed', [0.8500 0.3250 0.0980];
        'DarkRed' , [0.6350 0.0780 0.1840];
        'Yellow' , [0.9290 0.6940 0.1250];
        'Purple' , [0.4940 0.1840 0.5560];
        'Green' , [0.4660 0.6740 0.1880];
        'Black' , [0 0 0]};
[~, colorRowIdx] = ismember(lower(colorNames),lower(colorKey(:,1)));
colors = colorKey(colorRowIdx,2);
set(B, {'Color'}, colors)
Related Question