Freely available text book on using the Python Natural Language Toolkit. I’ve used nltk for several projects. It’s a fantastic toolkit and definitely worth a look if you have some NLP work. I have not read this text. It appears to be a more hands on introduction rather than a deep dive into NLP theory and nltk.
From the preface:
This book is a practical introduction to NLP. You will learn by example, write real programs, and grasp the value of being able to test an idea through implementation. If you haven’t learnt already, this book will teach you programming. Unlike other programming books, we provide extensive illustrations and exercises from NLP. The approach we have taken is also principled, in that we cover the theoretical underpinnings and don’t shy away from careful linguistic and computational analysis. We have tried to be pragmatic in striking a balance between theory and application, identifying the connections and the tensions. Finally, we recognize that you won’t get through this unless it is also pleasurable, so we have tried to include many applications and examples that are interesting and entertaining, sometimes whimsical.