同じ値が並んでいる範囲の検出

sames.st.end <- function(x){
# 差分を取る
	diff.x <- diff(x)
# 差分が0か否かで0/1に分ける
	s.x <- sign(abs(diff.x))
# その差分を取ると、同一値連続の左右端を検出
	diff.s.x <- diff(s.x)
# 左右端に連続かかっているかどうかで処理が分岐する
	st <- 1
	end <- c()
	init <- 0
	for(i in 1:length(diff.s.x)){
		if(diff.s.x[i]==-1){
			if(init==0){
				st <- i+1
			}else{
				st <- c(st,i+1)
			}
		}else if(diff.s.x[i]==1){
			if(init==0){
				init <- 1
			}
			end <- c(end,i+1)
		}
	}
	if(length(st) > length(end)){
		end <- c(end,length(x))
	}
	cbind(st,end)
}

s <- sort(runif(10))
x <- c()
n <- sample(1:5,length(s),replace=TRUE)
for(i in 1:length(s)){
	x <- c(x,rep(s[i],n[i]))
}
x

out.same <- sames.st.end(x)

for(i in 1:length(out.same[,1])){
	print(x[out.same[i,1]:out.same[i,2]])
}

> x
 [1] 0.1795974 0.1795974 0.1795974 0.1795974 0.3117404 0.3466666 0.3466666
 [8] 0.4574810 0.4778495 0.4778495 0.5505267 0.5505267 0.5505267 0.5505267
[15] 0.7426378 0.7458155 0.7587828 0.7587828 0.8995060
> out.same <- sames.st.end(x)
[1] 0.1795974 0.1795974 0.1795974 0.1795974
[1] 0.3466666 0.3466666
[1] 0.4778495 0.4778495
[1] 0.5505267 0.5505267 0.5505267 0.5505267
[1] 0.7587828 0.7587828