Multitopic Text Clustering and Cluster Labeling Using Contextualized Word Embeddings

Abstract

Context. In the current information era, the problem of analyzing large volumes of unlabeled textual data and its further grouping with respect to the semantic similarity between texts is emerging. This raises the need for robust text analysis algorithms, namely, clustering and extraction of key data from texts. Despite recent progress in the field of natural language processing, new neural methods lack interpretability when used for unsupervised tasks, whereas traditional distributed semantics and word counting techniques tend to disregard contextual information.Objective. The objective of the study is to develop an interpretable text clustering and cluster labeling methods with respect to the semantic similarity that require no additional training on the user's dataset.Method. To approach the task of text clustering, we incorporate deep contextualized word embeddings and analyze their evolution through layers of pretrained transformer models. Given word embeddings, we look for similar tokens across all corpus and form topics that are present in multiple sentences. We merge topics so that sentences that share many topics are assigned to one cluster. One sentence can contain a few topics, it can be present in more then one cluster simultaneously. Similarly, to generate labels for the existing cluster, we use token embeddings to order them based on how much they are descriptive of the cluster. To do so, we propose a novel metric -token rank measure and evaluate two other metrics.Results. A new unsupervised text clustering approach was described and implemented. It is capable of assigning a text to different clusters based on semantic similarity to other texts in the group. A keyword extraction approach was developed and applied in both text clustering and cluster labeling tasks. Obtained clusters are annotated and can be interpreted through the terms that formed the clusters.Conclusions. Evaluation on different datasets demonstrated applicability, relevance, and interpretability of the obtained results. The advantages and possible improvements to the proposed methods were described. Recommendations for using methods were provided, as well as possible modifications.