siegel.tukey=function(x,y,id.col=FALSE,adjust.median=F,rnd=-1,alternative="two.sided",mu=0,paired=FALSE,exact=FALSE,correct=TRUE,conf.int=FALSE,conf.level=0.95){
 if(id.col==FALSE){
   data=data.frame(c(x,y),rep(c(1,2),c(length(x),length(y))))
   } else {
	data=data.frame(x,y)
   }
 names(data)=c("x","y")
 data=data[order(data$x),]
 if(rnd>-1){data$x=round(data$x,rnd)}
 
 if(adjust.median==T){
	data$x[data$y==1]=data$x[data$y==1]-(median(data$x[data$y==1])-median(data$x[data$y==2]))/2
	data$x[data$y==2]=data$x[data$y==2]-(median(data$x[data$y==2])-median(data$x[data$y==1]))/2
 }
 cat("Median of group 1 = ",median(data$x[data$y==1]),"\n")
 cat("Median of group 2 = ",median(data$x[data$y==2]),"\n","\n")
 cat("Test of median differences","\n")
 print(wilcox.test(data$x[data$y==1],data$x[data$y==y]))
 
 a=rep(seq(ceiling(length(data$x)/4)),each=2)
 b=rep(c(0,1),ceiling(length(data$x)/4))
 
	# rk.up=c(1,(a*4+b))[1:ceiling(length(data$x)/2)]	# this method would lead to mistakes in calculating the ranks, it was corrected
	# rk.down=rev(c(a*4+b-2)[1:floor(length(data$x)/2)])
		#Example for when the old code would fail with the ranking:
			#x1 <- c(85, 106)
			#x2 <- c(96, 105, 104, 108, 86) # 108 should get rank 7 and not 8
			#iv <- rep(1:2, c(length(x1), length(x2)))
			#siegel.tukey(c(x1, x2), iv, id.col=TRUE)

	# Corrected code (17.12.10)
	X <- data$x
	N <- length(X) # N is the length of the combined data
	TF <- rep(c(TRUE, FALSE, FALSE, TRUE), ceiling(N/4))
	up <- TF[1:min(N, length(TF))]
	Rup <- rank(X)[up]
	Rdown <- rev(rank(X)[!up])
 
 cat("Performing Siegel-Tukey rank transformation...","\n","\n")
 
# rks=c(rk.up,rk.down)
 rks=c(Rup,Rdown)
 unqs=unique(sort(data$x))
 corr.rks=tapply(rks,data$x,mean)
 cbind(unqs,corr.rks)
 rks.data=data.frame(unqs,corr.rks)
 names(rks.data)=c("unique values of x","tie-adjusted Siegel-Tukey rank")
 print(rks.data,row.names=F)
 names(rks.data)=c("unqs","corr.rks")
 data=merge(data,rks.data,by.x="x",by.y="unqs")
 
 rk1=data$corr.rks[data$y==1]
 rk2=data$corr.rks[data$y==2]
 cat("\n","Tie-adjusted Siegel-Tukey ranks of group 1","\n")
 group1=data.frame(data$x[data$y==1],rk1)
 names(group1)=c("x","rank")
 print(group1,row.names=F)
 cat("\n","Tie-adjusted Siegel-Tukey ranks of group 2","\n")
 group2=data.frame(data$x[data$y==2],rk2)
 names(group2)=c("x","rank")
 print(group2,row.names=F)
 cat("\n")
 
 cat("Siegel-Tukey test","\n")
 cat("Siegel-Tukey rank transformation performed.","Tie adjusted ranks computed.","\n")
 if(adjust.median==T) {cat("Medians adjusted to equality.","\n")} else {cat("Medians not adjusted.","\n")}
 cat("Rank sum of group 1 =", sum(rk1),"    Rank sum of group 2 =",sum(rk2),"\n")
 
 
 print(wilcox.test(rk1,rk2,alternative=alternative,mu=mu,paired=paired,exact=exact,correct=correct,conf.int=conf.int,conf.level=conf.level))
}
 
#Example:

siegel.tukey.example <- function ()
{
	x=c(4,4,5,5,6,6)
	y=c(0,0,1,9,10,10)

	siegel.tukey(x,y)
}