About NLTK
NLTK is a Python API for the analysis of texts written in natural languages, such as English. NLTK was created in 2001 and was originally intended as a teaching tool.
Although we installed NLTK in the previous section, we are not done yet; we still need to download the NLTK corpora. The download is relatively large (about 1.8 GB); however, we only have to download it once. Unless you know exactly which corpora you require, it's best to download all the available corpora. Download the corpora from the Python shell as follows:
$ python3 >>> import nltk >>> nltk.download()
A GUI application should appear, where you can specify a destination and what file to download.
If you are new to NLTK, it's most convenient to choose the default option and download everything. In this chapter, we will need the stopwords, movie reviews, names, and Gutenberg corpora. Readers are encouraged to follow the sections in the ch-09.ipynb
file.