目标：查询目标点附近的10个最近邻邻居。
load fisheriris
x = meas(:,3:4);
figure(100);
g1=gscatter(x(:,1),x(:,2),species); %species分类中是有三个分类:setosa,versicolor,virginica
legend('Location','best')
newpoint = [5 1.45];
line(newpoint(1),newpoint(2),'marker','x','color','k',...
'markersize',10,'linewidth',2)
Mdl = KDTreeSearcher(x) ;
[n,d] = knnsearch(Mdl,newpoint,'k',10); %k代表个数，即搜索给定点附近的几个最近邻点
line(x(n,1),x(n,2),'color',[.5 .5 .5],'marker','o',...
'linestyle','none','markersize',10)
disp(x(n,:))
