查找向量中最后一次出现的唯一元素的索引

rle

vector

$lengths)

cumsum

rle

lengths

values

cumsum(rle(v1)$lengths)

#[1] 28 37 42 46 50

max

group

unname(cumsum(tapply(seq_along(v1),v1, FUN=which.max)))    

#[1] 28 37 42 46 50

TRUE

TRUE

which

 which(c(v1[-1]!=v1[-length(v1)],TRUE))

 #[1] 28 37 42 46 50

match

 c(match(unique(v1),v1)-1, length(v1))[-1]

#[1] 28 37 42 46 50

findInterval

 findInterval(unique(v1), v1)

 #[1] 28 37 42 46 50

v2

max.col(t(sapply(unique(v2), `==`, v2)),&＃x27;last&＃x27;)

#[1] 41 46 45 44 50 27

findInterval

ordering

   f1 <- function(v){

      v1 <- setNames(v, seq_along(v))

      ind <- order(v1)

      as.numeric(names(v1[ind][findInterval(unique(v1), v1[ind])]))

    }    



 f1(v2)

 #[1] 41 46 45 44 50 27

z

 f1(z)

 #[1] 4 5 3

z

1

3

2

order

v1 <- c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,

 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3,

 3, 4, 4, 4, 4, 5, 5, 5, 5)



v2 <-  c(1, 2, 1, 2, 1, 1, 1, 3, 1, 2, 2, 3, 3, 3, 1, 1, 1, 4, 1, 1,

 1, 4, 1, 5, 5, 6, 6, 2, 3, 3, 4, 4, 2, 2, 2, 2, 2, 3, 3, 3, 1,

 4, 4, 4, 3, 2, 5, 5, 5, 5)



 z <- c(1, 3, 2, 1, 3)