Change interval of color bar in contour scatter plot ?

Now I have my code plotting a scatter plot.

x = [1:0.1:10];
c = [10:-0.1:1];
y = zeros(1,91);
    y = y - 1;
    hold on
    scatter(x,y,[],c,'s','Fill')

How can I change the contour and colorbar interval to be a certain value [1:2:10]

[Adam Danz]

There isn't a "Levels" property of a scatter object. Looks like you're mixing up a contour plot with a scatter plot. That's gotta be straightened out before tending to your question.

q = scatter(___)
q.Levels = [0.3:0.1:1.3];  % ????

[Teerapong Poltue]

I've tried but it didn't work

[Adam Danz]

Please read that comment again.

I know it doesn't work.

What's a contour scatter plot?

Where is your contour plot?

Where is the colorbar?

[Teerapong Poltue]

Oh, sorry for that I put the wrong code in the topic.

I use the scatter plot for this (Example 3 in https://www.mathworks.com/help/matlab/ref/scatter.html).

x = [1:0.1:10];
c = [10:-0.1:1];
y = zeros(1,91);
    y = y - 1;
    hold on
    scatter(x,y,[],c,'s','Fill')
    

Then how can I change the color bar range for this code.

I would like to have some how like Levels of [1:2:10]

[Adam Danz]

See my answer below.

Answer 1

[Adam Danz]

> How can I change the color bar range for this code. I would like to have some how like Levels of [1:2:10]

This question is unclear and can be interpretted in several ways.

To change the color range use caxis().

To create a discrete colormap you've got several options.

If you only want n discrete colors you can use any of the colormap functions and specify the number of levels.

cmap = jet(n); 
cmap = cool(n); % etc...

You can combine that with caxis to define when the discrete colors change. For example,

% Create colorbar that ranges 0:10 and changes
% colors at 0:2:10
cmap = jet(5);
set(gca, 'Colormap',cmap)
cb = colorbar();
caxis([0,10])
set(cb, 'Ticks', 0:2:10)

To create a discrete colormap that indicates ranges of x-values of a scatter plot, you need to set the color input to scatter defined by the discrete ranges of x-values.

% Create scatter data 
x = 1:0.1:10;
y = zeros(1,91);

% Partition x values into bins to define color 
edges = min(x):2:max(x)+1;
c = discretize(x, edges);
c = edges(c);

% Plot results
figure()
ax = axes();
scatter(ax, x,y,[],c,'s','Fill')
grid(ax, 'on')
ax.XTick = edges;
colormap(ax, jet(numel(edges)-1)); % set colormap
caxis(edges([1,end]))              % set color range
cb = colorbar();
cb.Ticks = edges;
xlim([min(x)-1, max(x)+1])

[Teerapong Poltue]

Thanks for that, very appreciated.