Book Image

NLTK Essentials

By : Nitin Hardeniya
Book Image

NLTK Essentials

By: Nitin Hardeniya

Overview of this book

<p>Natural Language Processing (NLP) is the field of artificial intelligence and computational linguistics that deals with the interactions between computers and human languages. With the instances of human-computer interaction increasing, it’s becoming imperative for computers to comprehend all major natural languages. Natural Language Toolkit (NLTK) is one such powerful and robust tool.</p> <p>You start with an introduction to get the gist of how to build systems around NLP. We then move on to explore data science-related tasks, following which you will learn how to create a customized tokenizer and parser from scratch. Throughout, we delve into the essential concepts of NLP while gaining practical insights into various open source tools and libraries available in Python for NLP. You will then learn how to analyze social media sites to discover trending topics and perform sentiment analysis. Finally, you will see tools which will help you deal with large scale text.</p> <p>By the end of this book, you will be confident about NLP and data science concepts and know how to apply them in your day-to-day work.</p>
Table of Contents (17 chapters)
NLTK Essentials
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

What is text wrangling?


It's really hard to define the term text/data wrangling. I will define it as all the pre-processing and all the heavy lifting you do before you have a machine readable and formatted text from raw data. The process involves data munging, text cleansing, specific preprocessing, tokenization, stemming or lemmatization and stop word removal. Let's start with a basic example of parsing a csv file:

>>>import csv
>>>with open('example.csv','rb')  as f:
>>>    reader = csv.reader(f,delimiter=',',quotechar='"')
>>>    for line in reader :
>>>        print line[1]    # assuming the second field is the raw sting

Here we are trying to parse a csv, in above code line will be a list of all the column elements of the csv. We can customize this to work on any delimiter and quoting character. Now once we have the raw string, we can apply different kinds of text wrangling that we learned in the last chapter. The point here is to equip you...