From: Martin Stannard <martin@...>
Date: 2002-10-11T09:12:13+09:00
Subject: Sorting an array of hashes

Hi,

I've an array of hashes I want to sort, first by key1 and then subsort by
key2. I've some code that works but was wondering if there is a more
idiomatic method of doing this in Ruby:

# create an array of Hashes. We want to sort by firstKey, then secondKey.
unsorted = []
100.times do |t|
  unsorted.push({ "firstKey" => rand(10), "secondKey" => t})
end

# get an array of unique firstKeys 
firstKeys = []
unsorted.each { |hash| firstKeys.push(hash["firstKey"]) }
firstKeys.uniq!.sort!

finalArray = []
firstKeys.each do |aKey|
  # find all the items of aKey
  firstKeyMatches = unsorted.find_all { |hash| hash["firstKey"] == aKey}
  # sort them and add to the finalArray
  finalArray += firstKeyMatches.sort {|x,y| x["secondKey"] <=>
y["secondKey"] }
end

# the result
finalArray.each { |hash| puts "firstKey [#{hash["firstKey"].to_s.rjust(4)}]
secondKey [#{hash["secondKey"].to_s.rjust(4)}]" }

===================

regards,

Martin