Create a hash from an array of keys

Question

I have looked at other questions in SO and did not find an answer for my specific problem.

I have an array:

a = ["a", "b", "c", "d"] 

I want to convert this array to a hash where the array elements become the keys in the hash and all they the same value say 1. i.e hash should be:

{"a" => 1, "b" => 1, "c" => 1, "d" => 1} 

Answer 1

My solution, one among the others :-)

a = ["a", "b", "c", "d"] h = Hash[a.map {|x| [x, 1]}] 

Answer 2

There are several options:

• to_h with block:

  a.to_h { |a_i| [a_i, 1] } #=> {"a"=>1, "b"=>1, "c"=>1, "d"=>1} 

• product + to_h:

  a.product([1]).to_h #=> {"a"=>1, "b"=>1, "c"=>1, "d"=>1} 

• transpose + to_h:

  [a,[1] * a.size].transpose.to_h #=> {"a"=>1, "b"=>1, "c"=>1, "d"=>1}