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.

It is difficult to draw a closed polar coordinate curve.

load data1.mat

x=data1(:,1);y=data1(:,2);

hold on

plot(centroids(:,1),centroids(:,2),'b*')

[x y]=data1;

[theta,r] = cart2pol(x,y);

% closing the circle

r(end+1) = r(1);

theta(end+1) = theta(1);

% convert to cartesian

[x,y] = pol2cart(theta,r);

% interpolate with parameter t

t = (1:n)';

v = [x,y];

tt = linspace(1,n,100);

X = interp1(t,v,tt,'pchip');

% plot

plot(x,y,'o');

hold on

plot(X(:,1),X(:,2));

Answer 1

[Mathieu NOE]

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')