Pattern is a web mining module for Python. It has tools for:

• Data Mining: web services (Google, Twitter, Wikipedia), web crawler, HTML DOM parser
• Natural Language Processing: part-of-speech taggers, n-gram search, sentiment analysis, WordNet
• Machine Learning: vector space model, clustering, classification (KNN, SVM, Perceptron)
• Network Analysis: graph centrality and visualization.

It is well documented, thoroughly tested with 350+ unit tests and comes bundled with 50+ examples. The source code is licensed under BSD.