gistfile1.rb

def self.days_of_week time_ago
  days = Hash.new(0)
  Transaction.find_each(:conditions => ["created_at > ?", time_ago]) do |t|
    days[t.created_at.strftime('%A')] += 1 if t == t.user.transactions.first(:order => 'created_at')
  end
  puts days.sort{|a,b| b[1]<=>a[1]}.inspect
end

# [["Saturday", 44], ["Sunday", 62], ["Friday", 69], ["Monday", 80], ["Thursday", 93], ["Tuesday", 110], ["Wednesday", 115]]