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Python 3 Text Processing with NLTK 3 Cookbook

You're reading from   Python 3 Text Processing with NLTK 3 Cookbook

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Product type Paperback
Published in Aug 2014
Publisher
ISBN-13 9781782167853
Length 304 pages
Edition 2nd Edition
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Author (1):
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Jacob Perkins Jacob Perkins
Author Profile Icon Jacob Perkins
Jacob Perkins
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Table of Contents (12) Chapters Close

Preface 1. Tokenizing Text and WordNet Basics FREE CHAPTER 2. Replacing and Correcting Words 3. Creating Custom Corpora 4. Part-of-speech Tagging 5. Extracting Chunks 6. Transforming Chunks and Trees 7. Text Classification 8. Distributed Processing and Handling Large Datasets 9. Parsing Specific Data Types A. Penn Treebank Part-of-speech Tags
Index

Creating a chunked phrase corpus


A chunk is a short phrase within a sentence. If you remember sentence diagrams from grade school, they were a tree-like representation of phrases within a sentence. This is exactly what chunks are: subtrees within a sentence tree, and they will be covered in much more detail in Chapter 5, Extracting Chunks. The following is a sample sentence tree with three Noun Phrase (NP) chunks shown as subtrees:

This recipe will cover how to create a corpus with sentences that contain chunks.

Getting ready

The following is an excerpt from the tagged treebank corpus. It has part-of-speech tags, as in the previous recipe, but it also has square brackets for denoting chunks. The text within the brackets has been highlighted to make the chunks more apparent. The following sentence is the same sentence as in the previous tree diagram, but in text form:

[Earlier/JJR staff-reduction/NN moves/NNS] have/VBP trimmed/VBN about/IN [300/CD jobs/NNS] ,/, [the/DT spokesman/NN] said/VBD...
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