The social role of library to assist patrons learn becomes more important toward the future. As our society is changing rapidly and our lives are getting longer, we will keep wishing to learn while we live. So it becomes hard to catch up with the changes of patrons' needs and requirements to libraries if librarians keep working based on the traditional role model. A recommendable idea is to utilize the objective data libraries can get useful knowledge and tips for services and management. Such knowledge backed by data could be very helpful in capturing the patrons' needs for libraries. In this paper, we focus on data analysis for library's learning assisting feature; especially on patron profiling from circulation records of Kyushu University Library. First, we review the measure for expertise level of a book and a patron, which we call prank. Then we propose two concepts for measuring interest range size and earnestness in learning. We compare faculties in their features by applying these measures. It is expectable that such an approach of library marketing with data analysis will eventually reaches to the level in the future so that the measures and tools developed in this approach will become essential for libraries in order to catch up with the environmental changes of patrons and social needs to them.