Adding fading Background color (green --> yellow --> red) to plot(x,y)

I would like to add a fading colors into the backoground when using plot(x,y).

starting with green at 1.0 and below, fading to yellow (1.2) and yellow fading to red (1.8 and higher). This color schema shall be appllied in both directions x and y.

The following code does only color fading from green to red but noth using yellow:

xdata = [1.378 1.398 1.467 1.558 1.393 1.277 1.775 1.327];
ydata = [1.350 1.660 1.477 1.615 1.471 1.350 1.959 1.400];

figure(11); clf;
plot(xdata,ydata,'o'); grid;
axis square;
axis([1 2 1 2]);

% only two colors green --> red
hold on;
p = patch([1.00 2.00 2.00 1.00],[1.00 1.00 2.00 2.00],...
    [1 0.63 0.48],'FaceVertexCData',[0 1 0; 1 0 0; 1 0 0; 1 0 0],...
    'FaceColor','interp','EdgeColor','none','FaceAlpha',0.5); % light red
hold off;

Thank you for your help!

Answer 1

[Mathieu NOE]

hello daniel

try this and tune the pos_yellow parameter to get exactly the visual aspect yu want

xdata = [1.378 1.398 1.467 1.558 1.393 1.277 1.775 1.327];
ydata = [1.350 1.660 1.477 1.615 1.471 1.350 1.959 1.400];
figure(11); clf;
plot(xdata,ydata,'o'); grid;
axis square;
axis([1 2 1 2]);
% 3 colors green --> yellow --> red
hold on;
pos_yellow = 1.4; % try between 1.2 and 1.5 to match visually your expectations
p = patch([1 pos_yellow 2 2 1 1],[1 1 1 2 2 pos_yellow],[1 0.63 0.48],...
   'FaceVertexCData',[0 1 0; 1 1 0; 1 0 0; 1 0 0; 1 0 0; 1 1 0],...
    'FaceColor','interp','EdgeColor','none','FaceAlpha',0.5); % light red
hold off;

[Daniel Leibundgut]

Merci bien Mathieu!

Your proposal helps, additional challenge: now we have yellow at the x/y-points: [1 pos_yellow] and [pos_yellow 1] --> how to extend that at [pos_yellow pos_yellow] the color yellow is visible?

[Mathieu NOE]

hello again Daniel

so first version gave this

I tried this second version

code :

xdata = [1.378 1.398 1.467 1.558 1.393 1.277 1.775 1.327];
ydata = [1.350 1.660 1.477 1.615 1.471 1.350 1.959 1.400];
figure(11); clf;
plot(xdata,ydata,'o'); grid;
axis square;
axis([1 2 1 2]);
% 3 colors green --> yellow --> red
hold on;
pos_yellow = 1.4; % try between 1.2 and 1.5 to match visually your expectations

%% version #1 
% p = patch([1 pos_yellow 2 2 1 1],[1 1 1 2 2 pos_yellow],[1 0.63 0.48],...
%    'FaceVertexCData',[0 1 0; 1 1 0; 1 0 0; 1 0 0; 1 0 0; 1 1 0],...
%     'FaceColor','interp','EdgeColor','none','FaceAlpha',0.5); % light red

%% version #2 
p = patch([pos_yellow 2 1 1 pos_yellow],[pos_yellow 1 1 2 pos_yellow],[1 0.63 0.48],...
   'FaceVertexCData',[1 1 0; 1 0 0; 0 1 0; 1 0 0; 1 1 0],...
    'FaceColor','interp','EdgeColor','none','FaceAlpha',0.5); % light red
p = patch([pos_yellow 2 2 1 pos_yellow],[pos_yellow 1 2 2 pos_yellow],[1 0.63 0.48],...
   'FaceVertexCData',[1 1 0; 1 0 0; 1 0 0; 1 0 0; 1 1 0],...
    'FaceColor','interp','EdgeColor','none','FaceAlpha',0.5); % light red
hold off;

[Daniel Leibundgut]

great, thank you!

[Mathieu NOE]

My pleasure !

Answer 2

[Chunru]

xdata = [1.378 1.398 1.467 1.558 1.393 1.277 1.775 1.327];
ydata = [1.350 1.660 1.477 1.615 1.471 1.350 1.959 1.400];
figure(11); clf;
plot(xdata,ydata,'o'); grid;
axis square;
axis([1 2 1 2]);
% only two colors green --> red
hold on;

% Adjust the vertex color
% [0 1 0; 1 0 0; 1 1 0; 1 0 0] => G R Y R for the 4 corners
p = patch([1.00 2.00 2.00 1.00],[1.00 1.00 2.00 2.00],...
    [1 0.63 0.48],'FaceVertexCData',[0 1 0; 1 0 0; 1 1 0; 1 0 0],...
    'FaceColor','interp','EdgeColor','none','FaceAlpha',0.5); % light red
hold off;