Lightning post. I got very confused earlier today on how to use `duplicated`

. Basically, I didn’t know if it was picking only one duplicate or many of the duplicates at the same time. I figure it out but I still was a bit confused so I decided to rewrite the function from scratch. Below you can see it. Please post any other solutions or feedback.

```
dupl_identifier <- function(vec, where) {
intm <- x %in% vec
pos <- which(intm)
intm[where(pos)] <- FALSE
intm
}
my_duplicated <- function(x, fromLast = FALSE) {
where <- ifelse(!fromLast, min, max)
repeated <- names(which(table(x) > 1))
if (length(repeated) == 0) return(rep(FALSE, length(x)))
val <- lapply(repeated, dupl_identifier, where)
final <- as.logical(Reduce(`+`, val))
final
}
```

```
x <- sample(1:10, 100, replace = TRUE)
identical(my_duplicated(x),
duplicated(x))
```

`## [1] TRUE`

```
x <- sample(c(1:100, NA), 100, replace = TRUE)
identical(my_duplicated(x),
duplicated(x))
```

`## [1] TRUE`