gistfile1.rb

# Hash for each brand.  
# Each key is an item of that brand, in a format like 'id:type:name'.  
# Each value is a json string representing an array of user ids.

# For this query we would:

# iterate over each brand 
# pull the the keys that match our type ('*jeans*') and 
# get the user ids array for each brand of jeans.  

# Then something like this, where "brand" in this case is a constructed object 
# from the above operation, with name and user_id_array_for_jeans:


results = {}
brands.each do |b|
  jean_wearers = b.user_id_array_for_jeans
  results[brand.name] = User.where(:id => jean_wearers).where(demographic_conditions).count
end

results.sort_by {|brand, count| count}