For text data, we usually need to assign proper weights to words/terms
to reflect how important a word is to a document in a collection or corpus. One of the most popu-
lar term-weighting schemes is Term Frequency–Inverse Document Frequency (TF-IDF),
and 83% of text-based recommender systems in digital libraries use TF-IDF. The following steps
demonstrate how TF-IDF is calculated