Generate random moving nodes inside two intersecting circle

2016 8 29
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更新时间：2016 8 30
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Hi everyone, I am trying to generate random points inside a circle given the radius and the center. If anyone has a sample code or can help me with this. thanks.

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KSSV
KSSV 2016-8-30

1 个投票

clc; clear all ;
N1 = 100 ; N2 = 50 ;
th = linspace(0,2*pi,N1)' ;
r1 = 1. ; r2 = 1. ; % radii of circles
c1 = [0 0] ; % center of first cirlce
c2 = [1.5 0] ; % center of second circle
a1 = repmat(c1,[N1 1])+[r1*cos(th) r1*sin(th)] ;
a2 = repmat(c2,[N1 1])+[r2*cos(th) r2*sin(th)] ;
%
plot(a1(:,1),a1(:,2),'r') ;
hold on
plot(a2(:,1),a2(:,2),'r') ;
axis equal
%%Get points of fitst circle lying in second circle
in12 = inpolygon(a1(:,1),a1(:,2),a2(:,1),a2(:,2)) ;
P1 = a1(in12,:) ;
plot(a1(in12,1),a1(in12,2),'.b') ;
%%Get points of second circle lying in first circle
in21 = inpolygon(a2(:,1),a2(:,2),a1(:,1),a1(:,2)) ;
P2 = a2(in21,:) ;
plot(a2(in21,1),a2(in21,2),'.b') ;
%%form the oval / intersection boundary
R = [P1 ;P2] ;
%%Form a suare grid around ovel region
x = linspace(c1(1),c2(1),N2) ;
y = linspace(-r1,r2,N2) ;
[X,Y] = meshgrid(x,y) ;
XX = X(:) ; YY = Y(:) ;
%%Get the random points inside the region
l = 1 ;
ax = min(R(:,1)) ; bx = max(R(:,1)) ;
ay = min(R(:,2)) ; by = max(R(:,2)) ;
while l ==1
x = (bx-ax).*rand(1,1) + ax;
y = (by-ay).*rand(1,1) + ay;
in = inpolygon(x,y,R(:,1),R(:,2)) ;
if in
plot(x,y,'.g') ;
drawnow
end
end

更多回答（1 个）

KSSV
KSSV 2016-8-29
编辑：KSSV 2016-8-29

0 个投票

clc; clear all ;
C = [0 0] ; % center of the circle
R = 1. ; % Radius of the circle
N = 100 ;
th =linspace(0,2*pi) ;
xc = C(1)+R*cos(th) ;
yc = C(2)+R*sin(th) ;
plot(xc,yc,'b') ;
hold on
axis equal
% Generate random numbers using polar coordinates
for i = 1:N
r = R * sqrt(rand(1,1)) ;
theta = 2 * pi * rand(1,1) ;
x = r * cos(theta) ;
y = r * sin(theta) ;
plot(x,y,'.r')
drawnow
end

3 个评论
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Akande Oluwole
Akande Oluwole 2016-8-29
Thanks for the help, but the solution is only for a circle. The problem is not yet solved. The random nodes must be inside two intersecting circles of the same radius
KSSV
KSSV 2016-8-29
Two circles have different center? You have two circles of same radii and they intersect..you will get a oval shape, you want random numbers inside this? Ask question clearly.
Akande Oluwole
Akande Oluwole 2016-8-30
Yes, 1. two circles with different center, 2. having the same radius 3. both intersecting such that the distance between the two centers is greater than the radius. 4. nodes randomly generated inside the two circles and the intersecting area.

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