This is a well written book on the topic of Text Analysis. There is enough information to give you a good start using R. Followed by easy to understand details about text analysis.
Covered in Chapter 6 type token ratio, TTR.
Chapter 7 hapex legomena, words that appear in frequency.
Chapter 8, KWIC Key word context. Including how to make a corpus.
Chapter 11, covers clustering. Chapter 12, classification Shows how to do crosstabs with xtabs function. Also SVM support Vector Machine.
Chapter 13 covers topic modeling.
This is a good book to have if you are doing text analysis.