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Python Machine Learning Cookbook

You're reading from   Python Machine Learning Cookbook 100 recipes that teach you how to perform various machine learning tasks in the real world

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Product type Paperback
Published in Jun 2016
Publisher Packt
ISBN-13 9781786464477
Length 304 pages
Edition 1st Edition
Languages
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Authors (2):
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Vahid Mirjalili Vahid Mirjalili
Author Profile Icon Vahid Mirjalili
Vahid Mirjalili
Prateek Joshi Prateek Joshi
Author Profile Icon Prateek Joshi
Prateek Joshi
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Toc

Table of Contents (14) Chapters Close

Preface 1. The Realm of Supervised Learning FREE CHAPTER 2. Constructing a Classifier 3. Predictive Modeling 4. Clustering with Unsupervised Learning 5. Building Recommendation Engines 6. Analyzing Text Data 7. Speech Recognition 8. Dissecting Time Series and Sequential Data 9. Image Content Analysis 10. Biometric Face Recognition 11. Deep Neural Networks 12. Visualizing Data Index

Converting text to its base form using lemmatization


The goal of lemmatization is also to reduce words to their base forms, but this is a more structured approach. In the previous recipe, we saw that the base words that we obtained using stemmers don't really make sense. For example, the word "wolves" was reduced to "wolv", which is not a real word. Lemmatization solves this problem by doing things using a vocabulary and morphological analysis of words. It removes inflectional word endings, such as "ing" or "ed", and returns the base form of a word. This base form is known as the lemma. If you lemmatize the word "wolves", you will get "wolf" as the output. The output depends on whether the token is a verb or a noun. Let's take a look at how to do this in this recipe.

How to do it…

  1. Create a new Python file, and import the following package:

    from nltk.stem import WordNetLemmatizer
  2. Let's define the same set of words that we used during stemming:

    words = ['table', 'probably', 'wolves', 'playing'...
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