CODEWITHSUNDEEP
matlab
Hoàng Văn Hiếu
Hoàng Văn Hiếu

Reputation: 11

Plotting with a matrix in Matlab

The thing is i have a matrix and when i use imagesc() it goes like this but my goal is this. So my question is does any one know which plot is this or some one has document about this, thanks.

Upvotes: 0

Views: 320

Answers (1)

Ben Farris
Ben Farris

Reputation: 19

If you have two vectors r and theta that give the polar coordinates, or two matrices rGrid and thetaGrid that give the polar coordinates for each element of the data matrix, then code like this will work:

r=linspace(1,20,20);
theta=linspace(0,2*pi,20);

data = r'.*sin(2.*theta); % INSERT DATA HERE

[thetaGrid,rGrid]=meshgrid(theta,r); % Create coordinate grid if needed
[xGrid,yGrid]=pol2cart(thetaGrid,rGrid);

surf(xGrid,yGrid,data); % Plot data
view(2);

Polar plot

Just keep in mind that the rows of the data matrix need to correspond to different radii, and columns need to correspond to different values of theta. If it's flipped, then transpose the matrix before plotting:

data = data';

Also, if the data doesn't wrap around from 0 to 2*pi radians, then repeat the first value of theta as the last value, and repeat the first column of the data matrix as a new final column:

theta(end+1)=theta(1);
data=cat(2,data,data(:,1));

There is also a 3D Polar Plot function on the MATLAB file exchange, but I do not have any experience using it: 3D Polar Plot

Upvotes: 1

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