Scaling color with selected axis data

I want to plot a function z = f (x,y), but I want the lines (y-axis) to be the color scale.

This is my code:

% parameters
x= [0:1:30]' ;
y= linspace(0.1,10,length(x)) ;

% function
if (x <= max(x)*ones(size(x)) )
z = (x./max(x)).^y   ;
  else
z =  1 ;
end

% Plot
fig1 = plot3(x,y,z) ;
view([-120 20])
xlabel('x')
ylabel('y')
zlabel('z')
colorbar

[Rahul Kumar]

I think you should change the sequence of plot as x,z,y.

[Aikaterini Mountraki]

Than you for your reply, but even so, the lines still have random colors, they are not scaled as a function of y.

Moreover, what you are suggesting can also be done without changing the order of the plot with:

caxis(ylim)

Answer 1

[darova]

Why not use surf()?

Color lines using patch()

clc,clear

% parameters
x= [0:1:30]' ;
y= linspace(0.1,10,length(x)) ;
[X,Y] = meshgrid(x,y);
X(end+1,:) = nan;                   % put NaN where line ends
Y(end+1,:) = nan;
% function
Z = (X./max(x)).^Y   ;
  
% plot preparations
n = length(x);
cm = jet(n);                        % create 31 colors
z0 = linspace(min(Z(:)),max(Z(:)),n);
cmap = interp1(z0,cm,Z(:));         % get color for each Z
% cmap(isnan(cmap)) = 0;            % replace NaN

% Plot
cla
f = 1:length(Z(:))-1;
p = patch('Vertices',[X(:),Y(:),Z(:)], ...
        'Faces', [f' f'+1],...
        'EdgeColor','interp', ...
        'FaceVertexCData',cmap);
%         'Marker','.');

view([-120 20])
xlabel('x')
ylabel('y')
zlabel('z')
colorbar

% if graphical driver fails
% opengl software

Answer 2

[Ankit]

Hello Aikaterini,

Please try this out:

 % parameters
x= [0:1:30]' ;
y= linspace(0.1,10,length(x)) ;
% function
if (x <= max(x)*ones(size(x)) )
z = (x./max(x)).^y   ;
  else
z =  1 ;
end
% Plot
fig1 = plot3(x,y,z) ;
view([-120 20])
xlabel('x')
ylabel('y')
zlabel('z')
cb = colorbar;
set(gca, 'clim', get(gca, 'ylim'));
set(cb, 'Ticks', get(gca, 'ytick'));

Regards

Ankit

[Aikaterini Mountraki]

Ankit thank you for your reply. It is an interesting suggestion, but the lines still get random colors.

[Ankit]

Just give it a try! here i get the colormap and the later set it to the colorbar. But I dont see the difference Just to give you an Idea!

% parameters
x= [0:1:30]' ;
y= linspace(0.1,10,length(x)) ;
% function 
if (x <= max(x)*ones(size(x)) )
z = (x./max(x)).^y   ;
  else
z =  1 ;
end
% Plot
fig1 = plot3(x,y,z) ;
view([-120 20])
xlabel('x')
ylabel('y')
zlabel('z')
cmap = colormap(gca);
cb = colorbar;
set(gca, 'clim', get(gca, 'ylim'));
set(cb, 'colormap', cmap);
set(cb, 'Ticks', get(gca, 'ytick'));