```
x <- c(1:10, 4:6)
AllDuplicated(x)
# compare to:
duplicated(x)
x[!AllDuplicated(x)]
# union, intersect and friends...
A <- c(sort(sample(1:20, 9)),NA)
B <- c(sort(sample(3:23, 7)),NA)
# all elements from A and B (no duplicates)
union(A, B)
# all elements appearing in A and in B
intersect(A, B)
# elements in A, but not in B
setdiff(A, B)
# elements in B, but not in A
setdiff(B, A)
# Does A contain the same elements as B?
setequal(A, B)
# Find ties in a vector x
x <- sample(letters[1:10], 20, replace=TRUE)
ties <- split(x, x)
# count tied groups
sum(sapply(ties, length) > 1)
# length of tied groups
(x <- sapply(ties, length))[x>1]
# by means of table
tab <- table(x)
tab[tab>1]
# count elements involved in ties
sum(tab>1)
# count tied groups
sum(tab[tab>1])
```

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