Organizing users' friends in personal social networks, i.e., ego networks, into circles are an important task for online social networks. Social networking sites allow users to manually categorize their friends into social circles. However, it is time consuming and does not update automatically as a user adds more friends. In this paper, the authors propose an edge-based clustering algorithm to detect social circles in ego networks automatically. Firstly, they reconstruct ego networks by predicting the missing links. Then, they define the similarity of adjacent edges and cluster edges by single-linkage hierarchical clustering algorithm.