Topical and geographical alignment. Left and middle plots: Average similarity of the libraries (resp., groups) of aNobii users as a function of their distance in the social network. The similarity is measured by the average number of common books or groups (top, , ), and by the average cosine similarity (bottom, , ) between the books lists (resp., groups). In both cases, the same similarity after random reshuffling of items is shown. Right plots: Fraction of pairs of users at distance d in the union network residing in the same country () or town (). In both cases data from the network with reshuffled links are shown.