MATLAB: Contour plot of polar coordinates

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i have a 189*189 matrix which gives me a vector field in r and theta. I want a contour plot of that matrix. Any help would be greatly appreciated!

Best Answer

Try the following. I transformed the polar coordinates to cartesian coordinates and then obtained a contour polar plot.

load('theta.mat');
load('r.mat');
% Convert to Cartesian
x = r.*cos(theta);
y = r.*sin(theta);
z = r-theta;
h = polar(x,y);
hold on;
contourf(x,y,z);

Related Solutions

MATLAB: Help with MESH command

Did you mean something like this?

[r,theta] = meshgrid(linspace(0,1,30),linspace(0,2*pi,30));
x = r.*cos(theta);
y = r.*sin(theta);
z = r;
mesh(x,y,z)

MATLAB: How to create a contour plot in polar coordinates

A function that creates a polar contour plot is not present in MATLAB.

True polar axes are not supported in MATLAB. The POLAR function does the following to create a plot:

1. Accepts polar coordinates

2. Converts the data to Cartesian coordinates and plots them.

3. Draws the polar grid lines and text on a Cartesian axes system.

To create a contour plot in polar coordinates, you will need to follow a similar procedure. The following code shows an example:

% Create polar data
[r,t] = meshgrid(0:.1:5,0:pi/30:(2*pi));
z = r - t;
% Convert to Cartesian
x = r.*cos(t);
y = r.*sin(t);

Next, you can produce the annotations using the POLAR function and create the contour plot:

h = polar(x,y);
hold on;
contourf(x,y,z);
% Hide the POLAR function data and leave annotations
set(h,'Visible','off')
% Turn off axes and set square aspect ratio
axis off
axis image

Some of the annotations may be obscured when the contour plot is drawn. The most reliable way to work around this issue is to manually redraw them using the Plot Tools GUI or the ANNOTATION function.

Best Answer

Related Solutions

MATLAB: Help with MESH command

MATLAB: How to create a contour plot in polar coordinates

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