MATLAB: Generate coordinates circle,square,rectangle

generate matrixMATLABpoints

Hello,

I have to generate points(matrix),so that i have view the points as a circle(square,rectagle), when i display points(matrix) through plot.

Could someone help me?

Thanks.

Best Answer

For circle and ellipse, see the FAQ for code examples: http://matlab.wikia.com/wiki/FAQ?title=FAQ&cb=7341#How_do_I_create_a_circle.3F

For a square or rectangle, if you have x1, x2, y1, and y2, you can make it with plot by making coordinates of the box and calling plot

xBox = [x1 x2 x2 x1 x1];
yBox = [y1 y1 y2 y2 y1];
plot(xBox, yBox, 'r-', 'LineWidth', 2);

Of course that can ge generalized to any polygon, just list all the vertices.

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MATLAB: Filling a 2D area between 3 curves (Hypocycloid)

%radius big (fix) circle
R=4;
%radius small (rolling) circle
r=1;
phi=linspace(0,360,1000)*pi/180; phi(end)=[];
%parametric form hypocyloide (point at the rolling circle)
x=(R-r)*cos(phi)+r*cos(phi*((R-r)/r));
y=(R-r)*sin(phi)-r*sin(phi*((R-r)/r));
%parametric form big (fix) circle
x1=R*cos(phi);
y1=R*sin(phi);
%these points should give the position of the rolling circle at a specfic
%phi value (here: phi = 0.25*pi)
mx=(R-r)*cos(0.25*pi);
my=(R-r)*sin(0.25*pi);
%parametric form small (rolling) circle
x2=mx+x1*r/R;
y2=my+y1*r/R;
%plotting of hypocycloide, bigger circle, smaller circle 
plot(x,y)
hold on
plot(x1,y1)
plot(x2,y2)
hold off
hcyc=polyshape(x,y);
circ1=polyshape(x1,y1);
circ2=polyshape(x2,y2);
reg=regions(  polybuffer( subtract(circ1,union(hcyc,circ2)) ,-0.001 ));
hold on
plot(reg(3),'FaceColor',[1,1,1]/2)
hold off
axis equal,axis([-4 +4 -4 +4]),

MATLAB: Hello everyone, I now have a set of data. I would like to ask how to draw these scattered points in polar coordinates with the centroid point as the center.

hello

this would be my suggestion :

load data1.mat
load centroids.mat
x=data1(:,1)-centroids(:,1); % centered plot

y=data1(:,2)-centroids(:,2); % centered plot
[theta,r] = cart2pol(x,y);
% closing the circle
r(end+1) = r(1);
theta(end+1) = theta(1);
% sort theta in ascending order
[theta_sorted,ind] = sort(theta);
r_sorted = r(ind);
% remove duplicates before interpolation
[theta_unique,IA,IC] = unique(theta_sorted);
r_unique = r_sorted(IA);
% interpolation on n values to make it nicer
n = 360;  % 1 deg resolution
theta_n = linspace(min(theta_unique),max(theta_unique),n);
r_n = interp1(theta_unique,r_unique,theta_n);
% convert to cartesian
[xn,yn] = pol2cart(theta_n,r_n);
%% XY plot
figure(1),plot(x,y,'b.',xn,yn,'o');grid
%% polar plot 
figure(2),polarplot(theta_n, r_n,'--r')

Best Answer

Related Solutions

MATLAB: Filling a 2D area between 3 curves (Hypocycloid)

MATLAB: Hello everyone, I now have a set of data. I would like to ask how to draw these scattered points in polar coordinates with the centroid point as the center.

Related Question