Plot 3d plot with different colors depending on the X and Y combination

I am plotting a 3D plot, (X,Y,Z).

X and Y are indexes from 1 to 44.

I want that the bar plot color of Z depands on the values of X and Y.

For example:

when X =1 and Y = 20 so the Z bar has to be in color green

when X =10 and Y = 40 so the Z bar has to be in color red

when X =42 and Y = 40 so the Z bar has to be in color blue

The array combination of X and Y are stored in varriable IN, OUT.

for example

IN=[1 5 6 7 8 9 2 10....] (22 values)

OUT=[20 44 21 ....] (22 values)

Answer 1

[Cris LaPierre]

See this page: https://www.mathworks.com/help/matlab/creating_plots/color-3-d-bars-by-height-1.html

and this Answer: https://www.mathworks.com/matlabcentral/answers/403031-how-do-i-prevent-bar3-shading-the-sides-of-the-bars

Here's the example from that page.

Z = magic(5);
b = bar3(Z);
colorbar

for k = 1:length(b)
    zdata = b(k).ZData;
    ix=isfinite(zdata(:,1)); 
    zdata(ix,1)=zdata(ix,2);
    b(k).CData = zdata;
    b(k).FaceColor = 'flat';
end

[Tesla]

Thank you for your answer but i want to change the Z bar color according to the coordinates X and Y, as I explain in my question

[Cris LaPierre]

Now you see how to change the color of individual bars. Replace the values I used in my example to whatever values you want to use.

[Tesla]

Indeed I have a matrix of 44x44, so i have many conbination to do.

And I didnt understand well you suggestion

[Cris LaPierre]

Please share the code you will use to decide the color for an indiviual bar.

[Tesla]

here the Array IN and OUT:

IN = [NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	11	12	NaN	NaN	NaN	NaN	NaN	18	19	20	21	22	23	24	25	NaN	NaN	28	29	30	31	32	33	34	35	36	37	38	39	NaN	NaN	NaN	NaN	NaN]
OUT =[1	2	3	4	5	6	7	8	9	10	NaN	NaN	13	14	15	16	17	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	26	27	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	40	41	42	43	44]

my matrix is 44x44, the size of IN and OUT is 44, where there is NaN means there is no IN or OUT, and the other values are from 1 to 44 which are the indexes.

so you can see I have 3 conbinations (they are :

OUT with IN

OUT with Nan IN /and/ OUT NaN with IN are the same for me

NaN OUT with Nan IN.

so i want to plot the Z bar colors based on this condition.

hope you could understand my issue

[Tesla]

Here my matrix

[Cris LaPierre]

So how would you go about coding that up using your logic?

[Tesla]

Indeed that my issue to code that

[Cris LaPierre]

Share what you have tried so far. You might look into if-else or switch statements. See here.

[Tesla]

Okay I will try, thanks

[Tesla]

I tried to write this code, but not working for me, i tried many changes no luck

color_matrix = zeros(44, 44);
color_matrix(strcmp(matrix, 'D')) = 1;
color_matrix(strcmp(matrix, 'S')) = 2;
color_matrix(strcmp(matrix, 'DS')) = 3;
color_matrix(cellfun('isempty', matrix)) = 4;

[X, Y] = meshgrid(1:44, 1:44);
bar_colors = [0 0 0; 0 0 1; 0 1 0; 1 1 1];

figure;
ax = gca;
hold(ax, 'on');

for i = 1:numel(X)
    x = X(i);
    y = Y(i);
    z = Z(i); %% here where my data for Z are saved
    color_idx = color_matrix(i);
    h = bar3(ax, y, z, 1);
    
    zdata = ones(6 * size(z, 2), size(bar_colors, 2));
    zdata(:,:) = repmat(bar_colors(color_idx, :), 6 * size(z, 2), 1);
    set(h, {'ZData'}, {zdata});
    set(h, 'XData', x);
end

hold(ax, 'off');
view(ax, 3); 
xlabel(ax, 'X-axis');
ylabel(ax, 'Y-axis');
zlabel(ax, 'Z-axis');
title(ax, '3D Bar Plot');

[Cris LaPierre]

What is not working about it?

Answer 2

[Daniel]

You're interested in creating a bar chart where you can individually control the color of each bar, correct?

If so, you can start by creating a normal bar chart and collecting the handle, like so:

b = bar(0:5,6:-1:1)

b = 
  Bar with properties:

    BarLayout: 'grouped'
     BarWidth: 0.8000
    FaceColor: [0 0.4470 0.7410]
    EdgeColor: [0 0 0]
    BaseValue: 0
        XData: [0 1 2 3 4 5]
        YData: [6 5 4 3 2 1]

  Show all properties

Once you have the handle b, you can set the FaceColor property to 'flat'. This allows you to control the color of each bar individually with the CData property. The CData property has one row per bar, and one column per color.

% Colors are specified as [R G B], where each base color is in the range 0
% to 1.
redColor = [1 0 0];
greenColor = [0 1 0];
blueColor = [0 0 1];
grayColor = [0.5 0.5 0.5];

% You can read the X and Y data of each bar element through XData and
% YData. You can modify the color by changing CData.
% YData is a vector of the same length as your input.
% CData is a matrix with one row per input and one column per color.
b.FaceColor = 'flat';
for idx=1:length(b.XData)
    if b.YData(idx) == 1 % Extract elements from YData
        b.CData(idx,:) = redColor; % Extract rows from CData
    elseif b.YData(idx) == 3
        b.CData(idx,:) = greenColor;
    elseif b.YData(idx) == 5
        b.CData(idx,:) = blueColor;
    else
        b.CData(idx,:) = grayColor;
    end
end

[Tesla]

Thank you, but indeed i am talking about a 3D plot not 2D