Post on 18-Dec-2015
Text statistics 7Day 30 - 11/05/14LING 3820 & 6820
Natural Language Processing
Harry Howard
Tulane University
Course organization
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http://www.tulane.edu/~howard/LING3820/ The syllabus is under construction. http://www.tulane.edu/~howard/
CompCultEN/ Chapter numbering
3.7. How to deal with non-English characters 4.5. How to create a pattern with Unicode
characters 6. Control
Final project
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Open Spyder
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Review
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NLP, Prof. Howard, Tulane University
ConditionalFreqDist
1. >>> from nltk.corpus import brown
2. >>> from nltk.probability import ConditionalFreqDist
3. >>> cat = ['news', 'romance']
4. >>> catWord = [(c,w)
5. for c in cat
6. for w in brown.words(categories=c)]
7. >>> cfd=ConditionalFreqDist(catWord)
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Conditional frequency distribution
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A more interesting example
can could may might must will
news 93 86 66 38 50 389
religion 82 59 78 12 54 71
hobbies 268 58 131 22 83 264
sci fi 16 49 4 12 8 16
romance 74 193 11 51 45 43
humor 16 30 8 8 9 13
Conditions = categories, sample = modal verbs
1. # from nltk.corpus import brown2. # from nltk.probability import
ConditionalFreqDist3. >>> cat = ['news', 'religion', 'hobbies',
'science_fiction', 'romance', 'humor']4. >>> mod = ['can', 'could', 'may', 'might',
'must', 'will']5. >>> catWord = [(c,w)6. for c in cat7. for w in brown.words(categories=c)8. if w in mod]9. >>> cfd = ConditionalFreqDist(catWord)10. >>> cfd.tabulate()11. >>> cfd.plot()
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cfd.tabulate()
can could may might must will
news 93 86 66 38 50 389
religion 82 59 78 12 54 71
hobbies 268 58 131 22 83 264
science_fiction 16 49 4 12 8 16
romance 74 193 11 51 45 43
humor 16 30 8 8 9 13
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cfd.plot()
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Another example
The task is to find the frequency of 'America' and 'citizen' in NLTK's corpus of presedential inaugural addresses:1. >>> from nltk.corpus import inaugural2. >>> inaugural.fileids()
3. ['1789-Washington.txt', '1793-Washington.txt', '1797-Adams.txt', ..., '2009-Obama.txt']
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cfd2.plot()
First try
1. from nltk.corpus import inaugural
2. from nltk.probability import ConditionalFreqDist
3. keys = ['america', 'citizen']
4. keyYear = [(w, title[:4])
5. for title in inaugural.fileids()
6. for w in inaugural.words(title)
7. if w.lower() in keys]
8. cfd2 = ConditionalFreqDist(keyYear)
9. cfd2.plot()
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cfd2.plot()
Second try
1. from nltk.corpus import inaugural2. from nltk.probability import
ConditionalFreqDist3. keys = ['america', 'citizen']4. keyYear = [(key, title[:4])5. for title in inaugural.fileids()6. for w in inaugural.words(title)7. for k in keys8. if w.lower().startswith(k)]9. cfd3 = ConditionalFreqDist(keyYear)10. cfd3.plot()
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dfc3.plot()
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Stemming
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Third try
1. from nltk.stem.snowball import EnglishStemmer
2. stemmer = EnglishStemmer()
3. from nltk.corpus import inaugural
4. from nltk.probability import ConditionalFreqDist
5. keys = ['america', 'citizen']
6. keyYear = [(w, title[:4])
7. for title in inaugural.fileids()
8. for w in inaugural.words(title)
9. if stemmer.stem(w) in keys]
10. cfd4 = ConditionalFreqDist(keyYear)
11. cfd4.plot()
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cfd4.plot()
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Next time
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