unique-keys {hutils}

Unique keys

Description

A data.table's key need not be unique, but there are frequently circumstances where non-unique keys can wreak havoc. has_unique_key reports the existence of a unique key, and set_unique_key both sets and ensures the uniqueness of keys.

Usage

has_unique_key(DT)

set_unique_key(DT, ...)

Arguments

DT

A data.table

...

keys to set

Value

has_unique_key returns TRUE if DT has a unique key, FALSE otherwise. set_unique_key runs setkey(DT, ...) then checks whether the key is unique, returning the keyed data.table if the key is unique, or an error message otherwise.