perm.test.2<-function(x,y,iter=10000)
{
d<-c(x,y)
n1<-length(x)
n<-length(d)
difbar1<-rep(NA,iter)
difbar2<-rep(NA,iter)
for (i in 1:iter){
v<-sample(1:n,n1)
difbar1[i]<-mean(d[v])-mean(d[-v])
difbar2[i]<-median(d[v])-median(d[-v])}
dmean<-mean(x)-mean(y)
dmed<-median(x)-median(y)
p1<-sum(ifelse(difbar1>dmean,1,0))/iter
p2<-sum(ifelse(difbar2>dmed,1,0))/iter
list(obs.mean.dif=dmean,mean.dif.p.value=p1,obs.median.dif=dmed,median.dif.p.value=p2,perm.mean.difs=difbar1,perm.median.difs=difbar2)
}