Generate unique initial strings from array of strings

Question

I have a very long array of strings. For example:

["Abyssal Specter", "Air Elemental", "Aladdin's Ring", "Ambition's Cost", "Anaba Shaman", "Angel of Mercy", "Angelic Page", "Archivist", "Ardent Militia", "Avatar of Hope", "Aven Cloudchaser","Aven Fisher"]

Now this array must be passed to a method which should return

[["Abyssal Specter","Ab"], ["Air Elemental", "Ai"], ["Aladdin's Ring","Al"], ["Ambition's Cost","Am"], ["Anaba Shaman","Ana"], ["Angel of Mercy","Angel "], ["Angelic Page","Angeli"], ["Archivist","Arc"], ["Ardent Militia","Ard"], ["Avatar of Hope","Ava"], ["Aven Cloudchaser","Aven C"],["Aven Fisher","Aven F"]]

The method should return the unique initials of each string in the array.

For instance, "Abyssal Specter" should return "Ab" as there is no other string starting with "Ab". Similarly for "Air Elemental" to "Ai". But "Aven Cloudchaser" should return "Aven C", as there is a string "Aven Fisher". In short, it should just generate the unique string initials.

Answer 1

Abbrev in Standard Lib does exactly that:

require 'abbrev'

ar = ["Abyssal Specter", "Air Elemental", "Aladdin's Ring", "Ambition's Cost", "Anaba Shaman", "Angel of Mercy", "Angelic Page", "Archivist", "Ardent Militia", "Avatar of Hope", "Aven Cloudchaser","Aven Fisher"]
p ar.abbrev.invert.to_a

# [["Abyssal Specter", "Ab"], ["Air Elemental", "Ai"], ["Aladdin's Ring", "Al"], ["Ambition's Cost", "Am"], ["Anaba Shaman", "Ana"], ["Angel of Mercy", "Angel "], ["Angelic Page", "Angeli"], ["Archivist", "Arc"], ["Ardent Militia", "Ard"], ["Avatar of Hope", "Ava"], ["Aven Cloudchaser", "Aven C"], ["Aven Fisher", "Aven F"]]