Python Machine Learning Cookbook

Building a bag-of-words model

When we deal with text documents that contain millions of words, we need to convert them into some kind of numeric representation. The reason for this is to make them usable for machine learning algorithms. These algorithms need numerical data so that they can analyze them and output meaningful information. This is where the bag-of-words approach comes into picture. This is basically a model that learns a vocabulary from all the words in all the documents. After this, it models each document by building a histogram of all the words in the document.

How to do it…

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

   import numpy as np
   from nltk.corpus import brown
   from chunking import splitter

2. Let's define the ...