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Lecture 6: Comparing Things Word Similarity PowerPoint Presentation
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Lecture 6: Comparing Things Word Similarity

Lecture 6: Comparing Things Word Similarity

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Lecture 6: Comparing Things Word Similarity

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  1. Lecture 6: Comparing ThingsWord Similarity Methods in Computational Linguistics II Queens College

  2. Today List Comprehensions Determining Word Similarity Co-occurrences WordNet

  3. List Comprehensions Compact way to process every item in a list. [x for x in array]

  4. Methods Using the iterating variable, x, methods can be applied. Their value is stored in the resulting list. [len(x) for x in array]

  5. Conditionals Elements from the original list can be omitted from the resulting list, using conditional statements [x for x in array if len(x) == 3]

  6. Building up These can be combined to build up complicated lists [x.upper() for x in array if len(x) > 3 and x.startswith(‘t’)]

  7. Lists Containing Lists Lists can contain lists [[a, 1], [b, 2], [d, 4]] ...or tuples [(a, 1), (b, 2), (d, 4)] [ [d, d*d] for d in array if d < 4]

  8. Lists within lists are often called 2-d arrays This is another way we store tables. Similar to nested dictionaries. a = [[0,1], [1,0] a[1][1] a[0][0]

  9. Using multiple lists Multiple lists can be processed simultaneously in a list comprehension [x*y for x in array1 for y in array2]

  10. Co-occurrences • How would you identify common co-occurrences? • Define a co-occurrence: • “school bus” vs. “school river”

  11. How are words related?

  12. Some relations

  13. Anything else? What relationships would you like to know about between words?

  14. WordNet

  15. Synsets

  16. Other relationships in WordNet

  17. WordNet Similarity

  18. WordNet Similarity

  19. Word sense disambiguation

  20. Stemming and Lemmatizing

  21. Stemming and Lemmatization in NLTK

  22. WordNet Demo

  23. Next Time • Word Similarity • Wordnet • Data structures • 2-d arrays. • Trees • Graphs