a<-0; b<-10; int<-c(a,b)
#nx is number of X points (target) and ny is number of Y points (nontarget)
nx<-20; ny<-4; #try also nx<-40; ny<-10 or nx<-1000; ny<-10;
set.seed(1)
xr<-range(a,b)
xf<-(xr[2]-xr[1])*.1
Xp<-runif(nx,a-xf,b+xf)
Yp<-runif(ny,a,b) #try also Yp<-runif(ny,a+1,b-1)
ind<-ind.int.set(Xp,Yp)
ind
jit<-.1
yjit<-runif(nx,-jit,jit)
Xlim<-range(a,b,Xp,Yp)
xd<-Xlim[2]-Xlim[1]
plot(cbind(a,0), xlab=" ", ylab=" ",xlim=Xlim+xd*c(-.05,.05),ylim=3*c(-jit,jit),pch=".")
abline(h=0)
points(Xp, yjit,pch=".",cex=3)
abline(v=Yp,lty=2)
text(Xp,yjit,labels=factor(ind))
ind.int.set(3,5)
ind.int.set(6,5)
ind.int.set(Xp,Yp)
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