unique - return a vector containing the unique elements of an array
arr.unique()
The unique() method returns a vector
containing all unique elements from arr. All duplicate entries
are removed from the result. This is similar to APL ∪
vec.
A vector containing only the unique elements of arr.
ArgCheck if any arguments are provided.
a = [1, 2, 2, 3, 3, 3]
a.unique()
1 2 3
a = {"apple", "orange", "apple", "banana", "orange", "banana"}
a.unique()
apple orange banana