MATLAB: Simulate k nearest neighbourhood

simulate knn

Hi,
I want to simulate knn. When I add a new point on graph where other data points are on, it can predict class of it, but I don't have any idea about what to do after I upload a data set.

Best Answer

Play with this: 
x = rand(500,1) ; y = rand(500,1) ; 
l = kmeans([x y],4) ; 
figure
hold on
scatter(x,y,50,l,'o','filled')
N = 10 ; 
for i = 1:100
    % pick any point 
    [ptx,pty] = getpts() ; 
    idx = knnsearch([x y],[ptx pty],'k',N)' ;
    li = mean(l(idx)) ;
    text(ptx,pty,num2str(li))
    plot(ptx,pty,'*r')
    plot([ptx*ones(N,1) x(idx)]',[pty*ones(N,1) y(idx)]','r')
end
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