In natural language understanding (NLU) tasks, there is a hierarchy of lenses through which we can extract meaning — from words to sentences to paragraphs to documents. At the document level, one of the most useful ways to understand text is by analyzing its topics. The process of learning, recognizing, and extracting these topics across a collection of documents is called topic modeling.
In this post, we will explore topic modeling through 4 of the most popular techniques today: LSA, pLSA, LDA, and the newer, deep learning-based lda2vec.
note footnote at the bottom: "http://www.sciencemag.org/content/313/5786/504.abstract, http://www.cs.toronto.edu/~amnih/cifar/talks/salakhut_talk.pdf. In a strict sense, this work was obsoleted by a slew of papers from 2011 which showed that you can achieve similar results to this 2006 result with “simple” algorithms, but it’s still true that current deep learning methods are better than the best “simple” feature learning schemes, and this paper was the first example that came to mind. [return]"
Die Grundannahme für die Verwendung der PCA zur Clusteranalyse und Dimensionsreduktion lautet: Die Richtungen mit der größten Streuung (Varianz) beinhalten die meiste Information.