Turn an array into keys for hash

Question

How do I turn an Array into a Hash with values of 0 without an each loop.

For example, given this array:

[1, 2, 3, 4]

I want to get this hash:

{"1"=>0, "2"=>0, "3"=>0, "4"=>0}

Answer 1

The standard approach is Hash[...]:

Hash[xs.map { |x| [x.to_s, 0] }]

Or Enumerable#mash if you happen to use Facets. I cannot think of something more concise and declarative:

xs.mash { |x| [x.to_s, 0] }

Answer 2

array.inject({}) { | a, e | a[e.to_s] = 0; a }

or in a more clean way (thanks to tokland, see the discussion in the comments)

array.inject({}) { | a, e | a.update(e.to_s => 0) }