Cleanest way to create a Hash from an Array

Question

I seem to run into this very often. I need to build a Hash from an array using an attribute of each object in the array as the key.

Lets say I need a hash of example us

Answer 1

In case someone got plain array

arr = ["banana", "apple"]
Hash[arr.map.with_index.to_a]
 => {"banana"=>0, "apple"=>1}