Ruby Array Conundrum

array_conundrum.rb

elements = [["accesses.2013.12", "17"], ["accesses.2013.12", "18"], ["accesses.2013.12", "19"], ["accesses.2013.12", "20"], ["accesses.2013.12", "21"], ["accesses.2013.12", "22"], ["accesses.2013.12", "23"], ["accesses.2013.12", "24"], ["accesses.2013.12", "25"], ["accesses.2013.12", "26"], ["accesses.2013.12", "27"], ["accesses.2013.12", "28"], ["accesses.2013.12", "29"], ["accesses.2013.12", "30"], ["accesses.2013.12", "31"], ["accesses.2014.1", "01"]]
 
#
# I need to pair down this array into something usable, like:
#
elements = [
  {
    key: 'accesses.2013.12',
    days: [ 17, 18, 19 ]
  },
  {
    key: 'accesses.2014.1',
    days: [1]
  }
]

# keys are the unique elements from the first portion of each nested array.
# any ideas? Thank you!

This format is a bit different, but seems usable. Anything I'm missing?

output = {}
elements.each do |element|
key = element.first
value = element.last
output[key] ||= []
output[key] << value
end

output

output = {'key' => [value,value]}

This is even better than what I outlined originally. Thank you, Micah.