phpInsight is a sentiment classifier. It uses a dictionary of words that are categorised as positive, negative or neutral, and a naive bayes algorithm to calculate sentiment. To improve accuracy, phpInsight removes 'noise' words.
For example usage, see the examples folder.
License: GPLv3 or later
--- update 26-06-2018 ---
Library no longer allows a tie between positive and negative (pos/neg) sentiments, instead neutral (neu) sentiment is assumed.