Named Entity Recognition and Extractive Summarization
摘要
Clear walkthrough: what NER is, typical pipelines, R ecosystem survey (with a sensible focus on spacyr), then practical extraction (entities, adjectives, deps, timelines, complexity) and three extractive summarizers (lexRankr, LSAfun, textrank). You tie it back to marketing use-cases (brand/competitor mentions, negative reviews, timelines), and finish with exercises. Nice arc. This chapter explains how word embeddings turn words into numeric vectors that capture meaning from context, letting us measure similarity and perform operations like clustering and analogies. It starts with simple emotion vectors, then formalizes similarity with cosine similarity. The chapter walks through Word2Vec—both CBOW and skip-gram—including sliding windows, training with backpropagation, and negative sampling for efficient learning. It contrasts Word2Vec with GloVe and FastText, then moves to transformers (BERT/GPT): self-attention, positional encoding, encoder/decoder stacks, and why transformers produce contextual embeddings (the same word can have different vectors depending on usage).