Book-Crossings是由Cai-Nicolas Ziegler根据  bookcrossing.com 的数据编写的图书评分数据集。 它包含90000个用户的270000本书的110万个评分。评分范围从1到10，包括显式和隐式的评分。Book-Crossings数据集是最不密集的数据集之一，也是具有明确评分的最不密集的数据集。

Format

The Book-Crossing dataset comprises 3 tables.          

• BX-Users

  Contains the users. Note that user IDs (`User-ID`) have been anonymized and map to integers. Demographic data is            provided (`Location`, `Age`) if available. Otherwise, these fields contain NULL-values.




• BX-Books

  Books are identified by their respective ISBN. Invalid ISBNs have already been removed from the dataset. Moreover, some content-based information            is given (`Book-Title`, `Book-Author`, `Year-Of-Publication`, `Publisher`), obtained from Amazon Web Services. Note that in case            of several authors, only the first is provided. URLs linking to cover images are also given, appearing in three different flavours            (`Image-URL-S`, `Image-URL-M`, `Image-URL-L`), i.e., small, medium, large. These URLs point to the Amazon web site.




• BX-Book-Ratings

  Contains the book rating information. Ratings (`Book-Rating`) are either explicit, expressed on a scale from 1-10 (higher            values denoting higher appreciation), or implicit, expressed by 0.