A Semi-supervised Framework Based on Self-constructed Adaptive Lexicon for Persian Sentiment Analysis

With the appearance of Web 2.0 and 3.0, users’ contribution to WWW has created a huge amount of valuable expressed opinions. Considering the difficulty or impossibility of manually analyzing such big data, sentiment analysis, as a branch of natural language processing, has been highly considered. Despite the other (popular) languages, a limited number of research studies have been conducted in Persian sentiment analysis. In this study, for the first time, a semi-supervised framework is proposed for Persian sentiment analysis. Moreover, considering that one of the most recent studies in Persian, is an algorithm based on extracting adaptive (dataset-sensitive) expert-based emotional patterns. In this research, extraction of the same state-of-the-art emotional patterns is proposed to be performed automatically. Moreover, application of the HMM classifier, by utilizing the mentioned features (as its states) is analyzed; and additionally, HMM-based sentiment analysis is upgraded by being combined with a rule-based classifier for the opinion assignment process. In addition, toward intelligent self-training, a criterion for evaluating, the high reliability of output is presented by which (assuming satisfaction of the criterion) the self-training process is performed in “lexicon-extraction” and “classifier,” as learning systems. The proposed method, by being applied on the basis dataset, provides 90% of accuracy (despite its expert-independent lexicon generation nature), which in comparison with the supervised and semi-supervised methods in the state-of-the-art has a considerable superiority. Moreover, this semi-supervised method is evaluated by a 10/90 ratio of train/ test and its reliability is demonstrated by providing 80% of accuracy.