I've recently been researching the various ways the New Testament has been categorized by scholars. The obvious example is a grouping based on genre, with categories such as biography, historical, epistolary, and apocalyptic.
I've also been made aware of an entirely different categorization scheme which is based on the theological focus and tone of the author, as opposed to genre. The classic categories I've seen are Pauline, Johannine, Synoptic, and Petrine.
However, there are some books that are tricky to classify according to this scheme. For example, what category is James? "Jamine" perhaps? And is Jude normally classified as Petrine, or is it better to think of it as independent from the influence of the Petrine letters?
(In a nutshell, I'm looking for a categorization scheme which is complete, and which has some reasonable justification based on research and/or scholarly consensus)
Here is my attempt to group the books, for reference (I haven't included Acts, Jude, or James):