Automatic term extraction of dynamically updated text collections for sentiment classification into three classes
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An automatic term extraction approach for building a vocabulary that is constantly updated. A prepared dictionary is used for sentiment classification into three classes (positive, neutral, negative). In addition, the results of sentiment classification are described and the accuracy of methods based on various weighting schemes is compared. The work also demonstrates the computational complexity of generating representations for N dynamic documents depending on the weighting scheme used.
Automatic term extraction of dynamically updated text collections for sentiment classification into three classes
- 1. Automatic term extraction of dynamically updated text collections for sentiment classification into three classes Yuliya Rubtsova The A.P. Ershov Institute of Informatics Systems (IIS)
- 2. Applied problems which can be solved with sentiment classification ? consumer reviews study to commercial products for businesses;
- 4. Applied problems which can be solved with sentiment classification ? consumer reviews study to commercial products for businesses; ? recommender systems;
- 6. Applied problems which can be solved with sentiment classification ? consumer reviews study to commercial products for businesses; ? recommender systems; ? Human Machine Interface of a computer system which is responsible for adapting the system's behavior to the current emotional state of the person
- 7. Human Machine Interface of a computer system which is responsible for adapting the system's behavior to the current emotional state of the person ? psychological and medical diagnosis; ? safety control by analyzing the behavior of mass gatherings; ? assistance in carrying out investigative measures.
- 8. Most common sentiment analysis approaches Supervised machine learning Dictionaries and rules Combined method
- 9. Existing corpora ? Corpora of reviews which contain user marks ? Belongs to one subject domain (movies reviews, books reviews, gadgets reviews) ? Corps of news (a few emotional texts)
- 10. Filtration ? Texts containing both positive and negative emotions; ? Not informative tweets (less than 40 characters long); ? Copied texts and retweets.
- 11. Corpus of short texts consists of 114 991 – positive texts 111 923 – negative texts 107 990 – neutral texts
- 12. Corpus of short texts Collection type Number of words Number of unique words Positive messages 1 559 176 150 720 Negative messages 1 445 517 191 677 Neutral messages 1 852 995 105 239
- 13. Unique terms distribution in relation depending on the number of tweets 0 50000 100000 150000 200000 250000 300000 350000 400000 53 8213 16461 24624 32824 40999 49264 57414 65571 73660 81791 89882 97945 106068 114238 123009 131937 140682 149495 158284 167136 175859 184578 193442 202354 211426 220117 229570 238882 247995 256716 265561 274244 282350 Number of the unuque terms Number of texts
- 14. Uniformity of used collections Words frequency distribution
- 15. Most common approaches for used for N-grams extracting ? Manually, using a thesaurus. ? Term Extraction, based on significance of this term for a collection
- 16. Data sets characteristics ? The entire data set is known ? The entire data set is avaliable ? The entire data set is static (can’t change during calculation) When new document is added, it is necessary to the update the document frequency of many terms and all previously generated term weights needs recalibration. For N documents in a data stream, the computational complexity is O(N2).
- 17. Human speech is constantly changing => there is a need to update emotional dictionaries
- 18. Change in vocabulary and topics discussed Percentage of references to the Olympic theme on all 12% 0.50% 14% 12% 10% 8% 6% 4% 2% 0% posts Febrary August
- 19. Change in vocabulary and topics discussed Percentage of references to the vacation theme on all 0.06% 0.12% 0.14% 0.12% 0.10% 0.08% 0.06% 0.04% 0.02% 0.00% posts Febrary August
- 20. Change in vocabulary and topics discussed Percentage of using term “Sebyashka” (selfie – rus) on all 0.00% 0.02% 0.03% 0.02% 0.02% 0.01% 0.01% 0.00% posts Febrary August
- 21. Filtration ? Punctuation – commas, colons, quotation marks (exclamation marks, question marks and ellipses were retained); ? References to significant personalities and events ? Proper names; ? Numerals; ? All links were replaced with the word "Link" and were taken into consideration as a whole; ? Many dots were replaced with ellipsis.
- 22. TF-ICF C – number of categories, cf – the number of categories in which weighed term is found
- 23. TF-IDF tf – is the frequency of term occurrence in the collection (positive or negative tweets) , T – total number of messages in the collections, – the number of messages in the positive and negative T(ti ) collections contained the term
- 24. Experiments
- 25. Corpus of News texts consists of 46 339 – positive news 46 337 – negative news 46 340 – neutral news
- 26. ROMIP mixed collection consists of Reviews on books, movies, or digital camera from blogs 543– positive blog texts 236– negative blog texts 103– neutral blog texts
- 27. Short text collection TF-IDF TF-ICF Accuracy 95,5981 95,0664 Precision 0,958092631 0,953112184 Recall 0,955204837 0,94984672 F-Measure 0,956646554 0,95147665 News collection TF-IDF TF-ICF Accuracy 69,8619 58,1397 Precision 0,709246342 0,61278022 Recall 0,698624505 0,581402868 F-Measure 0,703895355 0,596679322 ROMIP collection TF-IDF TF-ICF Accuracy 53,9773 57,9545 Precision 0,561341047 0,558902611 Recall 0,5311636 0,535790598 F-Measure 0,545835539 0,547102625
- 28. Results
- 29. Experimental results in terms of F-measure 95.66 70.39 54.58 95.15 59.68 54.71 120 100 80 60 40 20 0 Short texts News Romip TF-IDF TF-ICF
- 30. The program module allows ? dynamically update the unigram dictionary, recalculate the weight of terms, depending on the accessories to the collection; ? take into account the lexical speech changes in time; ? investigate new terms entering into active vocabulary.
- 31. Thank you! Presentation: http://www.slideshare.net/mokoron Yuliya Rubtsova yu.rubtsova@gmail.com study.mokoron.com
Editor's Notes
- show that when the document set size is small, the unique term count continues to climb up as the number of documents increases. However, this growth of the unique term count is reduced sharply as the number of documents becomes very large. This observation indicates that if the document collection is sufficiently large, we can expect to see very few new words by adding more documents.
- References to significant personalities and events – the attitude towards them may vary over time, but a classifier trained on "old texts" will not be able to adapt quickly;