I recently wrote a Ruby gem called Perfecta, that wraps the Perfect Audience reporting API.
We use Perfect Audience for our retargeting campaigns and having the Ruby client makes it easy to integrate the reports and analytics into other systems.
gem install perfecta # or place this into your Gemfile and bundle install gem 'perfecta'
And then interacting with the API is as simple as
client = Perfecta::Client.new do |c| c.email = 'email@ddress' c.password = 'password' end p client.campaign_reports(interval: 'yesterday').inspect
Check out the project page for more info and usage instructions