Social networks are platforms for interaction, communication, and collaboration. Online social networking sites such as Facebook, LinkedIn, YouTube, Twitter, and Flickr are among the most popular sites on the Internet. Users of these sites, social actors, establish a social network. Social network platforms allow users to find, share, and organize content, to communicate, and to find contacts. Measuring contacts and interactions in social networks provides an opportunity to study the characteristics of online social network graphs at large scale, to analyze the structure of multiple online social networks, and to understand the complex dynamics of the interactions in social networks. Also, measuring contacts and interactions in social networks is important to improve current technologies of the systems and to develop new applications of online social ...