# Vocabulary/tildedot

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`~. y`Nub

Rank Infinity *-- operates on x and y as a whole, by items of y --*
WHY IS THIS IMPORTANT?

Removes duplicates from a list.

More generally, removes any item of an array that matches a preceding item.

~. 'abracadabra' abrcd

### Common Uses

1. Remove duplicate values from a list

~. 1 3 5 3 5 9 5 2 3 5 7 3 5 7 3 1 3 5 9 2 7

2. Remove duplicate rows from a table

]t =. _3 ]\ 1 0 1 1 1 0 1 0 1 0 1 0 1 1 0 1 0 1 1 1 0 1 0 1 0 1 0 1 1 0 ~. t 1 0 1 1 1 0 0 1 0

### Related Primitives

Nub Sieve (`~: y`)

### More Information

1. `~. y` is a member of the i. family.
1. `~. y` uses tolerant comparison. Use `~.!.0 y` for intolerant comparison.

Because of tolerant comparison, the number of items in `~. y` may depend on the order of the items of `y`.

1. The items of `~. y` preserve the order of their first occurrence in `y`.
1. The order of items in `~. y` is guaranteed to be the same as the order of partitions in `y u/.`.
1. `~. y` is equivalent to `(~: y) # y`.
1. If `y` is an atom, `~. y` is a 1-atom list. Otherwise the result of `~. y` has the same rank as `y`.