Lecture Summary
- Content analysis
- Analytical technique that can be used to extract secondary meaning from information
- Vocabulary Analysis - examine documents purely as a collection of words and look at patterns
- Readability Indexes - the ease with which a native speaker of average intelligence can read and understand a passage of text
- Normative Comparison - compare documents to some standard of normal text
- Natural Language Processing
- Make the computer understand natural language input and generate natural language output
- How is NLP done?
- Pre-Processing - remove useless parts of the documents
- Tokenization - break the raw text into meaningful units
- Normalization - e.g. cases
- Stemming - reduce words of different forms to the "root"
- Parts of Speech (POS) Tags
- Language Model - probabilitic models of sequences of words; enables word predictions
- unigram, bigram, trigram...
- p(wi) = c(wi)/N
- p(wi|wi-1) = c(wi-1wi)/C(wi-1)
- p(wi|wi-2wi-1) = c(wi-2wi-2wi)/C(wi-2wi-1)
- Google Book’s N-Gram Viewer
Notes
The main dish of this lecture is the steps of doing NLP. As a developer, most of the works can be done by simply calling libraries. However, we do need to understand the theories behind them. Among the introduced steps, I paid more attention on the N-Gram models. It is interesting to have computer predicting something that it doesn't really understand. I hope I can have chance to use those models in real life cases.
N-Gram Viewer is an interesting source of research. I will keep an eye on it.
N-Gram Viewer is an interesting source of research. I will keep an eye on it.