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Prepare for next time

Prepare for next time. No need to buy the book Free online at http://www.nltk.org/book Read Chapter 1 http://nltk.googlecode.com/svn/trunk/doc/book/ch01.html Install NLTK (see next slide) Warning: It might not be easy (and it might not be your fault) Let us know how it goes

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Prepare for next time

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  1. Prepare for next time • No need to buy the book • Free online at http://www.nltk.org/book • Read Chapter 1 • http://nltk.googlecode.com/svn/trunk/doc/book/ch01.html • Install NLTK (see next slide) • Warning: It might not be easy (and it might not be your fault) • Let us know how it goes • (both positive and negative responses are more appreciated)

  2. Installing NLTKhttp://nltk.googlecode.com/svn/trunk/doc/book/ch01.html • Chapter 01: pp. 1 - 4 • Python • NLTK • Data

  3. Homework

  4. George Miller’s Example: Erode • Exercise: Use “erode” in a sentence: • My family erodes a lot. • to eat into or away; destroy by slow consumption or disintegration • Battery acid had eroded the engine. • Inflation erodes the value of our money. • Miller’s Conclusion: • Dictionary examples are more helpful than defs Definition Examples George Miller: Chomsky’s Mentor & Wordnet

  5. Introduction to Programming Traditional (Start with Definitions) Non-Traditional (Start with Examples) Recursion def fact(x): if(x <= 1): return 1 else: return x * fact(x-1) Streams: Unix Pipes Briefly mentioned Everything else • Constants: 1 • Variables:x • Objects: • lists, strings, arrays, matrices • Expressions: 1+x • Statements: Side Effects • print 1+x; • Conditionals: • If (x<=1) return 1; • Iteration: for loops • Functions • Recursion • Streams

  6. Python def fact(x): if(x <= 1): return 1 else: return x * fact(x-1) def fact2(x): result=1 for i in range(x): result *=(i+1); return result • Exercise: Fibonacci in Python Recursion Iteration

  7. Lists

  8. Strings

  9. Subscripting

  10. Python Objects Lists Strings >>> sent1[0] 'Call' >>> type(sent1[0]) <type 'str'> >>> sent1[0][0] 'C' >>> sent1[0][1:len(sent1[0])] 'all' >>> sent1 ['Call', 'me', 'Ishmael', '.'] >>> type(sent1) <type 'list'> >>> sent1[0] 'Call' >>> sent1[1:len(sent1)] ['me', 'Ishmael', '.'] First Rest

  11. Flatten: Inverse of Split First >>> def flatten(list): if(len(list) == 1): return list[0]; else: return list[0] + ' ' + flatten(list[1:len(list)]); Rest flatten = split-1

  12. Types & Tokens Polymorphism Polymorphism

  13. Polymorphism(From Wikipedia)

  14. Flatten: Inverse of Split >>> def flatten(list): if(len(list) == 1): return list[0]; else: return list[0] + ' ' + flatten(list[1:len(list)]); +

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