MATLAB: Making a 2d polar plot with color

3d plotspolar

Hi I was able to create a contour polar plot using:

https://www.mathworks.com/matlabcentral/fileexchange/14826-polar-contour-plot

I have questions about my attachment picture:

How can I add gridlines?

Best Answer

I didn’t see your Question before.

I would run the grid-creating plot calls adding a ‘z’ value of zeros to work with your polar contour plot:

plot3(cc50(1,:), cc50(2,:), zeros(size(cc50(1,:))), 'k')            % Plot Full Circumference

plot3(cc30(1,:), cc30(2,:), zeros(size(cc30(1,:))), 'k')
plot3(cc10(1,:), cc10(2,:), zeros(size(cc10(1,:))), 'k')
plot3(rdx, rdy, zeros(size(rdx)), 'k')                              % Plot Radials

I have tested this, and it works as I want it to. I have not tested it with your code. It should work. For a 3D plot, the grids have to be specified as 3D objects themselves, and setting the ‘z’ values to zero does that. If you want the grids to be at a ‘z’ value other than zero, add the same scalar value to the zeros call.

Example:

kz = 20;
figure(1)
plot3(cc50(1,:), cc50(2,:), zeros(size(cc50(1,:)))+kz, 'k')            % Plot Full Circumference
hold on
plot3(cc30(1,:), cc30(2,:), zeros(size(cc30(1,:)))+kz, 'k')
plot3(cc10(1,:), cc10(2,:), zeros(size(cc10(1,:)))+kz, 'k')
plot3(rdx, rdy, zeros(size(rdx))+kz, 'k')                              % Plot Radials
hold off
axis equal
grid on
axis([-50  50    -50  50    0  25])

I am plotting this in the context of my previous code, using the calculations from it for the ‘cc’ and ‘rd’ variables.

Related Solutions

MATLAB: How to fill the area between two curves on a polar plot

Yes!

Yours are different. Yours are also an easier problem.

I set up everything in polar coordinates in that code, then used the pol2cart function to create Cartesian representations for them, and plotted them in Cartesian space. My code drew the polar coordinates the same way. It did not use polar or polarplot, since they do not offer the necessary options.

Set your data up in polar coordinates, use pol2cart, patch, then plot.

Use the Plot Full Circumference and Plot Radials section in my code your referred to, to plot the polar coordinate grid. Use the text function for the radial and angle labels if you want them. Use the values in the grid plotting part of my earlier code to get the (x,y) values for your text calls.

This code snippet should get you started:

theta = linspace(0, 2*pi, 18);                                      % Create Data (Angles)
Data1 = rand(1, 18)*0.5 + 0.5;                                      % Create Data (First Radius)
Data2 = rand(1, 18)*0.5;                                            % Create Data (Second Radius)
[x1, y1] = pol2cart(theta, Data1);                                  % Convert To Cartesian
[x2, y2] = pol2cart(theta, Data2);
figure(1)
patch([x1 fliplr(x2)], [y1 fliplr(y2)], 'g', 'EdgeColor','g')       % Fill Area Between Radius Limits
hold on
plot(x1, y1, '-k')
plot(x2, y2, '-r')
hold off
axis equal

Experiment to get the result you want. Post back if you have problems. I’ll do my best to help.

MATLAB: Fill area between two polar curves

The patch function will not work with polar axes. It throws this error:

Error using patch
While setting property 'Parent' of class 'Patch':
Patch cannot be a child of PolarAxes.

Oh, well...

The best I can do with this is to use pol2cart:

tau = 0.5;
r = linspace(eps, 1.5, 500);
phi = 0.87*sin((log(r)*pi)/(log(tau)));
phi_shifted_45 = 0.87*sin((log(r)*pi)/(log(tau)))+0.78;
[x1,y1] = pol2cart(phi, r);
[x2,y2] = pol2cart(phi_shifted_45, r);
figure(1)
patch([x1 fliplr(x2)], [y1 fliplr(y2)], 'g')
axis equal

Note to MathWorks: Can we have a patch for polar coordinate systems when you have time to implement it?

Best Answer

Related Solutions

MATLAB: How to fill the area between two curves on a polar plot

MATLAB: Fill area between two polar curves

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