Question

Each key in a hash has a value that’s also a hash.

    {
      100 => {
        1 => 'ruby',
        2 => 'enumerables'
      },
      50 => {
        3 => 'can',
        4 => 'cause'
      },
      15 => {
        5 => 'occassional',
        6 => 'insanity'
      }
    }

For each hash object, I want to discard the top-level key, and replace it with the key and value of the nested hash objects.

{
  1 => 'ruby',
  2 => 'enumerables',
  3 => 'can',
  4 => 'cause',
  5 => 'occasional',
  6 => 'insanity'
}

I have it working, but my method uses a merge!, and requires creating another hash to store the values. I’m curious to see if it can be done in one line. I tried to use reduce(), but could not make it work.

Answer 1

This works:

hash.values.inject(&:merge)

Edit: Another option, using reduce (which is the same as inject), and noting tokland’s comment that to_proc is automatically called when you use a symbol:

hash.values.reduce(:merge)

Then it becomes not only concise but very readable.