Worked examples from the NLTK Book
A Consumer Electronics Named Entity Recognizer - uses an NLTK Maximum Entropy Classifier and IOB tags to train and predict Consumer Electronics named entities in text.
A simple tool to detect word equivalences using Wordnet. Reads a TSV file of word pairs and returns the original (LHS) word if the words don't have the same meaning. Useful (at least in my case) for checking the results of a set of regular expressions to convert words from British to American spellings and for converting Greek/Latin plurals to their singular form (both based on patterns).
A Named Entity Recognizer for Genes - uses NLTK's HMM package to build an HMM tagger to recognize Gene names from within English text.
A trigram backoff language model trained on medical XML documents, and used to estimate the normalized log probability of an unknown sentence.
A proof of concept for calculating inter-document similarities for a collection of text documents for a cheating detection system. Contains implementation of the SCAM (Standard Copy Analysis Mechanism) in order to possible near-duplicate documents.
A proof of concept to identify significant word collocations as phrases from about an hours worth of messages from the Twitter 1% feed, calculated as a log-likelihood ratio of the probability that they are dependent vs that they are independent. Based on the approach described in "Building Search Applications: Lucene, LingPipe and GATE" by Manu Konchady, but extended to handle any size N-gram.
A trigram interpolated model trained on medical and legal sentences, and used to classify a sentence as one of the two genres.
Uses the same training data as medorleg, but uses Scikit-Learn's text API and LinearSVC implementations to build a classifier that predicts the genre of an unseen sentence.
Also contains an ARFF writer to convert the X and y matrices to ARFF format for consumption by WEKA. This was done so we could reuse Scikit-Learn's text processing pipeline to build a WEKA model, which could then be used directly from within a Java based data pipeline.
Using a POS tagged (Brown) corpus to build a dictionary of words and their sense frequencies, and using a chunked (Penn Treebank subset) corpus to build a reference set of POS sequences and POS state transitions to allow context free POS tagging of standalone words and phrase type detection of standalone phrases.
Topic modeling the PHR corpus with gensim. More information in these posts:
Using DBSCAN to cluster section titles in clinical notes.
Python/NLTK implementation of the algorithm described in the paper - Sentence Similarity Based on Semantic Nets and Corpus Statistics by Li, et al.
Drug name NER using one class classification approach. Only positive training set (drug name ngrams) are provided, along with an unlabelled dataset and estimate of proportion of positive data. More information on my blog post: Classification with Positive Examples only.