How do I create circular patches within two radii?

I am trying to create a polar plot with circular rings of constant values. I am able to create the patches, but do not know how to 'constrain' the colored values to the area between two radii. This is what I have so far - this is just a sample and does not contain any real values. I'm just trying to figure out how to code this right now.

Arbitrary values below. The colorbar values are set to be ranging from 0-40, and the two patch cdata values are set at 28 and 35.

numPoints=100; 
radius=100;      

theta=linspace(0,2*pi,numPoints);

rho=ones(1,numPoints)*radius; 

[X,Y] = pol2cart(theta,rho); 

radius=20;

rho=ones(1,numPoints)*radius;
[X,Y] = pol2cart(theta,rho);

H=patch(X,Y,1); 
set(gca,'CLim',[0 40])

cdata = ones(1,100)*28;

set(H,'FaceColor','interp',...
'CData',cdata,...
'CDataMapping','scaled',...
'EdgeColor','interp',...
'LineWidth',5)

colormap(jet)

hold on

radius=10;
rho=ones(1,numPoints)*radius;

[X,Y] = pol2cart(theta,rho);

H=patch(X,Y,1); 

cdata = ones(1,100)*35;

set(H,'FaceColor','interp',...
'CData',cdata,...
'CDataMapping','scaled',...
'EdgeColor','interp',...
'LineWidth',5)

What this is doing is just writing over the first patch with the second, smaller patch. Because of this, there is no interpolation between them.

Answer 1

[Walter Roberson]

numPoints = 100; 
numrings = 5;

cmap = jet(numrings);

radius = linspace(0,200,numrings+1);   %where the rings are to be drawn    
theta = linspace(0,2*pi,numPoints);
[THETA,RADIUS] = ndgrid(theta,radius);
[X,Y] = pol2cart(THETA,RADIUS);

for K = 1 : numrings
   xpoints = [X(:,K); flipud(X(:,K+1))];
   ypoints = [Y(:,K); flipud(Y(:,K+1))];
   patch(xpoints, ypoints, cmap(K,:), 'EdgeColor', 'none');
   hold on
end
hold off

Defining the circle with radius 0 to get the first ring makes the code simpler but you could do without it if you treated the ring at the origin differently. And this code works immediately if you use a lower bound that is not 0, if you want the first colored ring to start at a distance from the origin.

[AMart]

Thank you, Walter. This worked for me, and is a step in the right direction. I was wondering how to alter the cmap to correspond to certain values. For instance, I would like each ring, starting with the central circle, to have a color value corresponding to the following vector:

values1 = [365,355,350,345,340,335,330,325,319,300]';

I tried to alter cmap but received an error because my values were outside the required domain. Any ideas? I appreciate any help sincerely.

[Walter Roberson]

what does a color value in the range 300 to 365 mean?

It sounds like you want to associate particular data values with particular color indices. Are you trying to create something like a polar contour map?

[AMart]

Yes, that is exactly what I'm trying to create. My problem is that I have a multitude of data points scattered around the center of my plots, so simply running a linear interpolation creates a lot of noise due to distance weighting, etc. If you have advice on a better way to complete this, it would be awesome. Thanks.

[Walter Roberson]

I am not going to look at this until you clarify the difference with your new question http://uk.mathworks.com/matlabcentral/answers/247143-how-do-i-create-a-polar-plot-with-concentric-colored-rings-corresponding-to-single-values

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