How can I gradient the legend color in MATLAB?

I have a 3D-bar MATLAB code which represents data for 3-folds, as shown in the attached figure.

How can I gradient the legend color, ranging from #FFFF00 to #F68C00 and from #00FEEF to #3092E3, as shown in the big red box?

[Scott MacKenzie]

It would help if you attached the code that generated this chart. Also, do you only want the color gradient in the legend or do you also want the color of the bars in the chart to follow the gradient?

[Amal AbdelGawad]

Thank you for your response.

I only want the color gradient in the legend, ranging from #FFFF00 to #F68C00 and from #00FEEF to #3092E3.

This is a miniature version of the code:

clear all; close all; clc;
 
A_F1 = [1:1:5]'; A_F2 = [2:2:10]'; A_F3 = [3:3:16]'; %Actual data of Fold 1, 2, and 3
P_F1 = [2:1:6]'; P_F2 = [3:2:11]'; P_F3 = [4:3:18]'; %Predicted data of Fold 1, 2, and 3
Z = zeros(length(A_F1(:)),2); % 2 XTicks to be hided (to separate the folds visually)

figure;
b = bar3([A_F1,P_F1, ...
          Z,A_F2,P_F2, ...
          Z,A_F3,P_F3], 0.8); %"0.8" to separate the bars visually
b(1).FaceColor='#FFFF00'; b(5).FaceColor='#FBC600'; b(9).FaceColor='#F68C00'; %Yellow gradient for Actual
b(2).FaceColor='#00FEEF'; b(6).FaceColor='#18C8E9'; b(10).FaceColor='#3092E3'; %Blue gradient for Predicted
for i=3:1:4   b(i).FaceColor='none'; b(i).LineStyle='none'; end %The 1st 2 XTicks to be hided (btn. Fold 1 & 2)
for i=7:1:8 b(i).FaceColor='none'; b(i).LineStyle='none'; end %The 2nd 2 XTicks to be hided (btn. Fold 2 & 3
set(gca,'XTick', [1,5,9]');
set(gca,'XTickLabels', ['1','2','3']');
xlabel ('Fold No.','fontweight','b');
ylabel ('Instant No.','fontweight','b');
zlabel ('Data','fontweight','b');
legend('','','','', 'Actual','Predicted'); %Taking the color of the center fold
hold off;

It is producing this chart:

Answer 1

[DGM]

I don't know that there's a good way to do this, but there's probably a better way than the garbage I came up with.

%hl = legend('','','','', 'Actual','Predicted'); %Taking the color of the center fold

pleg = [0.8559 0.8220 0.08 0.1030];
txpos = 0.45;
pt1 = [pleg(1)+pleg(3)*txpos pleg(2)-pleg(4)*0.12 0.1 0.1];
pt2 = [pleg(1)+pleg(3)*txpos pleg(2)-pleg(4)*0.52 0.1 0.1];
a1 = annotation('rectangle',pleg,'facecolor','w');
t1 = annotation('textbox',pt1,'string','Actual','edgecolor','none','fitboxtotext','on');
t2 = annotation('textbox',pt2,'string','Predicted','edgecolor','none','fitboxtotext','on');
bh = 0.025;
bw = 0.008;
a11 = annotation('rectangle',[pleg(1)+pleg(3)*0.1      pleg(2)+pleg(4)*0.17 bw bh],'facecolor','#FFFF00','edgecolor','none');
a12 = annotation('rectangle',[pleg(1)+pleg(3)*0.1+bw   pleg(2)+pleg(4)*0.17 bw bh],'facecolor','#FBC600','edgecolor','none');
a13 = annotation('rectangle',[pleg(1)+pleg(3)*0.1+2*bw pleg(2)+pleg(4)*0.17 bw bh],'facecolor','#F68C00','edgecolor','none');
a21 = annotation('rectangle',[pleg(1)+pleg(3)*0.1      pleg(2)+pleg(4)*0.60 bw bh],'facecolor','#00FEEF','edgecolor','none');
a22 = annotation('rectangle',[pleg(1)+pleg(3)*0.1+bw   pleg(2)+pleg(4)*0.60 bw bh],'facecolor','#18C8E9','edgecolor','none');
a23 = annotation('rectangle',[pleg(1)+pleg(3)*0.1+2*bw pleg(2)+pleg(4)*0.60 bw bh],'facecolor','#3092E3','edgecolor','none');

This kind of works, but it's fragile.

If you ask me, 3D bar charts are a universally poor way to visualize anything, especially small differences between sets.