Next gen of word embeddings London 45 mins

How to get interchangeable or related words
Theory behind word2vec, fasttext, wordrank

Transcript

1. Next generation of word embeddings Lev Konstantinovskiy Community Manager at Gensim @teagermylk http://rare-technologies.com/
2. Streaming Word2vec and Topic Modelling in Python
3. Gensim Open Source Package • Numerous Industry Adopters • 170 Code contributors, 4000 Github stars • 200 Messages per month on the mailing list • 150 People chatting on Gitter • 500 Academic citations
4. Credits Parul Sethi Undergraduate student University of Delhi, India RaReTech Incubator program Added WordRank to Gensim http://rare-technologies.com/incubator/
6. Which words are similar?
7. “Coast” vs “Shore” ????
8. “Coast” vs “Shore” similar
9. “Clothes” vs “Closet” ????
10. “Clothes” vs “Closet” similar in the sense “related”
11. “Clothes” vs “Closet” different! Why?
12. “Clothes” vs “Closet” different! not “interchangeable”
13. Business Problems
14. Business Problems “What does Elizabeth think about Mr Darcy?” “Male characters in Pride and Prejudice?”
15. Two Different Business Problems 1) What words are in the topic of “Darcy”? 2) What are the Named Entities in the text?
16. Pride and Prejudice models
17. Closest word to “king”? Trained on Wikipedia 17m words Attribute Interchangeable Both
18. Theory of word embeddings
19. What is a word embedding? ‘Word embedding’ = ‘word vectors’ = ‘distributed representations’ It is a dense representation of words in a low-dimensional vector space. One-hot representation: king = [1 0 0 0.. 0 0 0 0 0] queen = [0 1 0 0 0 0 0 0 0] book = [0 0 1 0 0 0 0 0 0] king = [0.9457, 0.5774, 0.2224] Distributed representation:
20. Awesome 3D viz in TensorBoard
21. How to come up with the vectors?
22. Co-occurence matrix ... and the cute kitten purred and then ... ... the cute furry cat purred and miaowed ... ... that the cute kitten miaowed and she ... ... the loud furry dog ran and bit ... kitten context words: [cute, purred, miaowed]. cat context words: [cute, furry, miaowed]. dog context words: [loud, furry, ran, bit]. Credit: Ed Grefenstette https://github.com/oxford-cs-deepnlp-2017/
23. Co-occurence matrix kitten context words: [cute, purred, miaowed]. cat context words: [cute, furry, miaowed]. dog context words: [loud, furry, ran, bit]. Credit: Ed Grefenstette https://github.com/oxford-cs-deepnlp-2017/ cute furry bit kitten 2 0 0 cat 1 1 0 dog 0 1 1 X =
24. Dimensionality reduction More precisely, in word2vec u*v approximates PMI(X) - log n, in Glove log(X) cute furry bit … kitten 2 0 0 ... cat 1 1 0 ... dog 0 1 1 ... ... ... ... ... ... X = = U * V Dims: vocab x vocab = (vocab x small) * (small x vocab) First row of U is the word embedding of “kitten”
25. Dimensionality reduction More precisely u*v approximates PMI(X) - log n, where n is the negative sampling parameter Co-occurence score in word2vec = U word * V context Dims: count = (small vector) * (small vector)
26. FastText: word is a sum of its parts Co-occurence score in FastText = U subword * V context over all subwords of w going = go + oi + in + ng + goi + oin + ing
27. FastText better than word2vec because morphology Credit: Takahiro Kubo http://qiita.com/icoxfog417/items/42a95b279c0b7ad26589 Slower because many more vectors to consider!
28. FastText is better at interchangeable words Related words accuracy Interchangeable words accuracy Training time
29. Same API as word2vec. Out-of-vocabulary words can also be used, provided they have at least one character n-gram present in the training data. FastText Gensim Wrapper
30. FastText slower than Python word2vec. Even without n-grams... But Python is slower than C, right? :)
31. - Word2vec - FastText - WordRank - Factorise the co-occurence matrix: SVD/LSI - GLoVe - EigenWords - VarEmbed Many ways to get a vector for a word
32. WordRank is a Ranking Algorithm Word2vec Input: Context Cute Output: Word Kitten Classification problem WordRank Input: Context Cute Output: Ranking 1. Kitten 2. Cat 3. Dog Robust: Mistake at the top of the rank costs more than mistake at the bottom.
33. Gensim WordRank API is same as word2vec, FastText
34. Algorithm Train time (sec) Passes through corpus Related accuracy Related (WS-353) Interchange able accuracy Interchange able (SimLex-999 ) Word2Vec 18 6 4.69 0.37 2.77 0.17 FastText 50 6 6.57 0.36 36.95 0.13 WordRank 4hrs 91 15.26 0.39 4.23 0.09 Evaluation on 1 mln words corpus
35. Algorithm Train time (sec) Passes through corpus Related accuracy Related (WS-353) Interchang eable accuracy Interchan geable (SimLex-9 99) Word2Vec 402 6 40.34 41.48 0.69 41.1 FastText 942 6 25.75 57.33 0.67 45.2 WordRank ~42 hours 91 54.52 39.83 0.71 44.7 Evaluation on 17 mln words corpus
36. Algorithm Related accuracy Related (WS-353) Interchangeable accuracy Interchangeable (SimLex-999) Word2Vec Window = 2 21 0.63 36 0.33 Word2Vec Window = 15 40 0.69 40 0.31 Word2Vec Window = 50 42 0.68 34 0.26 Big window means less “interchangeable”
37. How to get the similarity you need My similar words must be Related Interchangeable I want to describe the word’s Topic Function I want to Know what doc is about Recognize names Then I should run Wordrank (even on small corpus, 1m words) or Word2vec skipgram big window needs large corpus >5m words Word2vec skipgram small window or FastText or VarEmbed
38. How to get the similarity you need “Similar words” are Related Interchangeable Got a million words? FastText Word2vec small context VarEmbed WordRank Word2vec large context Yes No
39. Thanks for listening! Lev Konstantinovskiy github.com/tmylk @teagermylk Coding sprint today 13:30 - 15:30 “Learn NLP by running Gensim tutorials” “Turn your FullFact project into a Gensim tutorial” Fix an easy bug on github.