Search icon CANCEL
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Conferences
Free Learning
Arrow right icon
Arrow up icon
GO TO TOP
Python 3 Text Processing with NLTK 3 Cookbook

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

Arrow left icon
Product type Paperback
Published in Aug 2014
Publisher
ISBN-13 9781782167853
Length 304 pages
Edition 2nd Edition
Languages
Tools
Arrow right icon
Author (1):
Arrow left icon
Jacob Perkins Jacob Perkins
Author Profile Icon Jacob Perkins
Jacob Perkins
Arrow right icon
View More author details
Toc

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

Swapping noun cardinals


In a chunk, a cardinal word, tagged as CD, refers to a number, such as 10. These cardinals often occur before or after a noun. For normalization purposes, it can be useful to always put the cardinal before the noun.

How to do it...

The swap_noun_cardinal() function is defined in transforms.py. It swaps any cardinal that occurs immediately after a noun with the noun so that the cardinal occurs immediately before the noun. It uses a helper function, tag_equals(), which is similar to tag_startswith(), but in this case, the function it returns does an equality comparison with the given tag:

def tag_equals(tag):
  def f(wt):
    return wt[1] == tag
  return f

Now we can define swap_noun_cardinal():

def swap_noun_cardinal(chunk):
  cdidx = first_chunk_index(chunk, tag_equals('CD'))
  # cdidx must be > 0 and there must be a noun immediately before it
  if not cdidx or not chunk[cdidx-1][1].startswith('NN'):
    return chunk

  noun, nntag = chunk[cdidx-1]
  chunk[cdidx-1]...
lock icon The rest of the chapter is locked
Register for a free Packt account to unlock a world of extra content!
A free Packt account unlocks extra newsletters, articles, discounted offers, and much more. Start advancing your knowledge today.
Unlock this book and the full library FREE for 7 days
Get unlimited access to 7000+ expert-authored eBooks and videos courses covering every tech area you can think of
Renews at $19.99/month. Cancel anytime