Clear Plot without clearing UI elements

I'm planning to plot this function (roulette wheel) onto another figure with UI controls. However, I was wondering if there was a way to clear just the roulette wheel plot (remove it along with the axis) without getting rid of the rest of the UI. I'm calling the roulette wheel using the RW(wNumber) from the main file, where wNumber is the randomly generated winning number.

Roulette wheel function:

function RW(wNumber)
    % Set parameters (these could be arguments to a function)
    rInner = 150;     % inner radius of the colour ring
    rOuter = 200;    % outer radius of the colour ring
    % this is the clockwise sequence for a european pattern single-green wheel
    slotnums = [0 32 15 19 4 21 2 25 17 34 6 27 13 36 11 30 8 23 10 5 24 16 33 1 20 14 31 9 22 18 29 7 28 12 35 3 26];
    slotColour = [1 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2];
    % slotColor used to index colours, 1 - green for 0, 2 - blacks, 3 - reds. Each
    % number from slotnums is assigned a corresponding slotidx
    CT = [0 0.5 0; 0.1 0.1 0.1; 0.5 0 0]; % Colours (percentage RGB scale, 
    % contains luminosity of colour), CT = Colour Table
    nslots = numel(slotnums); % number of colour segments (also used to 
    % calculate the angle of rotation per frame)
    
    SMAA=0:pi/20:2*pi; % pi/20 means there is 40 sides to the circle, smaller the 
    % increment smoother the ball
    x=cos(SMAA); %X coordinate of each vertex
    y=sin(SMAA); %Y coordinate of each vertex
    k=5;% Radius of ball
    ball(1,:) = k*x;
    ball(2,:) = k*y-170; %y-axis is flipped when using imagesc, so to offset 
    % vertically upwards needs a negative y offset
    
    landOn = find(slotnums == wNumber); %ball will land on the winning number
    
    for i = 0:1:36
        offset = i; % specify angle offset (degrees)
        % Use meshgrid to define a coordinate plane
        [x, y] = meshgrid(-220:220);
        % Get polar coordinates of each point in the domain
        [theta, rho] = cart2pol(x, y);
        
        % generate segments
        segm = mod(rad2deg(theta)+offset*30+90,360)/360; % normalize
        segm = ceil(segm * nslots); % quantize (denormalize [1,37]), splits the 
        % segments into 37 inividually addressable coloured segments
        segm = ind2rgb(segm,CT(slotColour,:)); %assigns rgb colour to each segment
        % Colour table is generated from the ind2rgb command, uses values from
        % slotColour (output is an MxNx3/RGB image)
    
        % Define boundaries of the annular region
        annular = double(rho >= rInner & rho <= rOuter);
        segm(repmat(~annular,[1 1 3])) = 0; %Vector [1 1 3] creates a MxNx3 Mask
        % second argument is number of times to replicate input for other
        % dimensions, repmat(~annular) = 0 (disable/black out) would only affect 
        % the reds
        % RGB Image components in terms of colour
        % Reds = [: : 1], Greens = [: : 2], Blues = [: : 3]
        % Additional comments: [1 1 0] = no segment is masked
        %                      [1 1 1] = only reds are masked
        %                      [1 1 2] = reds and greens are masked
        %                      [1 1 3] = all segments are masked
    
        % show result
        imagesc(-220: 220, -220: 220, segm); %Displays image with x 
        % & y axis borders from -200 to 200, NOTE: changing scale of axis does
        % not affect image itself, as the original coordinate plane is defined
        % as meshgrid(-rOuter:rOuter);. However it will affect the plots below
    
        axis off
        axis square
        hold on
    
        %hold on
        % add numbers
        textrad = rInner + 0.65*(rOuter-rInner); % distance of the radius between 
        % the text and center of circle (Also the hypoteneuse)
        th0 = 360/nslots; %Difference in angle between each segment/slot
        theta = linspace(0,360-th0,nslots) - offset*30 + 275; %offset*30, for 3 
        % complete rotations, +275 to move number 0 into correct position
        for k = 1:numel(theta) %Creates 37 numbers, as length of array elements is 37
            x = textrad*cosd(theta(k)); %Pythagoras for x coordinate (adjacent 
            % length = hypoteneuse * cos(theta)
            y = textrad*sind(theta(k)); %Pythagoras for y coordinate (opposite 
            % length = hypoteneuse * sin(theta)
            numLabel = text(x,y,sprintf('%d',slotnums(k))); %converts number to
            % double precision float (location of text is at [x,y])
            numLabel.Color = [1 1 1];
            numLabel.FontSize = 10;
            numLabel.FontWeight = 'bold';
            numLabel.HorizontalAlignment = 'center';
            numLabel.Rotation = 270-theta(k);
        end
    
        % Drawing the ball
        % For each iteration the angle changes by 2pi/n
        comrotShape1 = rotateabout(ball, ((2*pi)/nslots * (i+landOn))+(5/360)*2*pi, 0, 0);
        % 5/360*2*pi (converts offset angle of 5 degrees to rads) in clockwise
        % direction as rotateabout uses clockwise rotation matrix
        fill(comrotShape1(1,:),comrotShape1(2,:),[0.84 0.84 0.84]);
    
        % Instantly plots arrow without waiting for further graphical commands
        drawnow
        hold off
    
    
    pause(0.033)
    end
    
    function comrotShape = rotateabout(shape, a, p, q)
        % Combined rotation and translation of shape, comrotShape short for combined
        % rotation shape
            %Tranlsate by (-p, -q)
            Trans(1,:) = shape(1,:)-p;
            Trans(2,:) = shape(2,:)-q;
            
            %Rotate by a
            rShape = [cos(a) -sin(a); sin(a) cos(a)] * Trans;
            
            %Translate by (p, q)
            comrotShape(1,:) = rShape(1,:)+p;
            comrotShape(2,:) = rShape(2,:)+q;
    end
end

[Rik]

Why are you not using explicit handles everywhere for your graphics objects? That is considered best practice and helps when you want to delete elements.

[David]

Just to clear up some misconceptions about handles, can I just assign a handle to the fill object by writing:

ball = fill(comrotShape1(1,:),comrotShape1(2,:),[0.84 0.84 0.84]);

I've seen in other example code, that they've included an array at the start of the function [handles] = funcName:

Or is that just to group all the handles under one array?

[Walter Roberson]

ball = fill(comrotShape1(1,:),comrotShape1(2,:),[0.84 0.84 0.84]); 

That is fine to record a copy of the handle(s) returned by fill.

[David]

I was wondering if using an array would be the best method of deleting the axes elements:

        for k = 1:numel(theta) %Creates 37 numbers, as length of array elements is 37
            x = textrad*cosd(theta(k)); %Pythagoras for x coordinate (adjacent 
            % length = hypoteneuse * cos(theta)
            y = textrad*sind(theta(k)); %Pythagoras for y coordinate (opposite 
            % length = hypoteneuse * sin(theta)
            numLabel = text(x,y,sprintf('%d',slotnums(k))); %converts number to
            % double precision float (location of text is at [x,y])
            num(k) = numLabel %Place all the numbers into an array <--- added in
            numLabel.Color = [1 1 1];
            numLabel.FontSize = 10;
            numLabel.FontWeight = 'bold';
            numLabel.HorizontalAlignment = 'center';
            numLabel.Rotation = 270-theta(k);
        end
        
        delete(num) %<--- deletes all the number from the roulette wheel

So that I'll have an array called num, with elements defined by numLabel, which I can then use to delete all the numbers from. (It works, but I wanted to know if there was an even simpler way)

[Walter Roberson]

You could

delete(findobj(gca,'type','text'))

but that risks deleting other text entries, and is not as efficient as what you are doing.

It looks to me as if you could probably vectorize that code. You can compute all of the coordinates in vector form, and you can text() arrays of coordinates and arrays of labels, passing in parameters such as 'Color', [1 1 1] that are in common for all of the labels. The one trick would be to set the rotations to be different for all of them you would have to do

set(TextHandles, {'Rotation'}, num2cell(270-theta(:)))

This relies upon an obscure way to use set() to change properties of multiple handles at the same time.

[David]

Slightly indirect to the original question, but is there a way to make the msgbox always appear on top of the figure. Whenever I turn the UI elements from Visible 'off' to 'on', it reshuffles the GUI so that it goes above the message box.

else
            playerBalance = playerBalance - cash;
            runningTotal = runningTotal - cash;
            msgbox('Unlucky, try again!')%//Maybe turn this into a button <--
            pause(0.5)
            %'false'
        end
        chosenNumber %DEBUG
        %playerBalance = 600 //Debugging purposes

        %//Updates displayed player balance
        BALANCE.String = strcat("Cash: $",num2str(round(playerBalance)));
        runningTotalTitle.String = char('Running Total $:', num2str(runningTotal));
        
        %Re-enable buttons
        SPIN.Enable = 'on';
        ZERO.Visible = 'on';
        FELT.Visible = 'on';
        CHALK.Visible = 'on';
        Red.Visible = 'on';
        Black.Visible = 'on';
        EvenButton.Visible = 'on';
        OddButton.Visible = 'on';
        set(grid(:,:),'Visible','on');

[Walter Roberson]

@David See https://www.mathworks.com/matlabcentral/answers/7779-keep-always-on-top

Answer 1

[Walter Roberson]

UI controls are never the children of axes, so deleting or clearing the axes will not affect ui controls.

If you want to remove particular graphic elements leaving others intact, then depending what you need, it might be as simple as a findobj. For example,

delete(findobj(gca, 'type', 'patch'));   %get rid of the fill()