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Schema Matching and Data Extraction over HTML Tables

Learn how to automatically extract structured data from HTML tables, solve schema matching issues, infer mappings, and improve accuracy. Includes solutions and experimental results.

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Schema Matching and Data Extraction over HTML Tables

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  1. Schema Matching and Data Extraction over HTML Tables Cui Tao Data Extraction Research Group Department of Computer Science Brigham Young University supported by NSF

  2. Introduction • Many tables on the Web • Ontology-based extraction: • Works well for unstructured or semi-structured data • What about structured data – tables? • How to integrate data stored in different tables? • Detect the table of interest • Form attribute-value pairs (adjust if necessary) • Do extraction • Infer mappings from extraction patterns

  3. ? ProblemDetecting The Table of Interest

  4. Problem Different schemas • Different source table schemas • {Run #, Yr, Make, Model, Tran, Color, Dr} • {Make, Model, Year, Colour, Price, Auto, Air Cond., AM/FM, CD} • {Vehicle, Distance, Price, Mileage} • {Year, Make, Model, Trim, Invoice/Retail, Engine, Fuel Economy} • Target database schema {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}

  5. ProblemAttribute is Value

  6. ? ? Problem Attribute-Value is Value

  7. ProblemValue is not Value

  8. ProblemFactored Values

  9. ProblemSplit Values

  10. ProblemMerged Values

  11. Table extending over several pages List ProblemInformation Behind Links

  12. Solution • Detect the table of interest • Form attribute-value pairs (adjust if necessary) • Do extraction • Infer mappings from extraction patterns

  13. SolutionDetect The Table of Interest • Top-level tables • Table size: at least 3 rows and columns • Grid layout: same # of values • Attributes • Value density: # of ontology extracted values total # of values in the table

  14. SolutionDetect The Table of Interest • Linked-page tables • Table size: at least 2 rows and columns • Attributes • Attribute-value-pair pattern • Page-spanning tables

  15. 2001 2001 2001 2000 2000 2000 2000 2000 2000 1999 1999 Solution Remove Factoring

  16. SolutionReplace Boolean Values

  17. SolutionForm Attribute-Value Pairs <Make, Honda>, <Model, Civic EX>, <Year, 1995>, <Colour, White>, <Price, $6300>, <Auto, Auto>, <Air Cond., Air Cond.>, <AM/FM, AM/FM>

  18. SolutionAdjust Attribute-Value Pairs <Make, Honda>, <Model, Civic EX>, <Year, 1995>, <Colour, White>, <Price, $6300>, <Auto, Auto>, <Air Cond., Air Cond.>, <AM/FM, AM/FM>

  19. Unstructured and semi-structured: concatenate < Single attribute value pairs: Pair them together <Price, $7,988>, <Mileage, 63,168 miles>, <Body Type, Car>, <Body Style, 4 DR Sedan>, <Transmission, Automatic>, <Engine, 3.0 L V-6>, <Doors, 4>, <Fuel Type, Gas>, <Stock Number, 22764>, <VIN, 1FAFP52U2WA139879> List: Mark the beginning and the end > SolutionAdd Information Hidden Behind Links

  20. SolutionInferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}

  21. Each row is a car. SolutionInferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}

  22. SolutionInferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}

  23. SolutionInferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}

  24. SolutionInferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}

  25. SolutionInferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}

  26. SolutionInferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}

  27. SolutionInferred Mapping Creation {Car, Year, Make, Model, Mileage, Price, PhoneNr}, {Car, Feature}

  28. Precision:100% Recall:87% 15 46 Testing Set 53 87%(46) 2 28 12 13 100%(7) Training Set 7 100%(7) Top Table Location Structured Linked Page Location Linked Pages Experimental Results − Table Location Car advertisement application domain Precision:86% Recall: 92%

  29. Experimental Results − Mapping Car advertisement application domain • 46 recognized tables in the testing set • Total 319 mappings • Precision: 95.8% Recall: 92.8% • Top-level tables: 77% of the 296 correct mappings • Linked tables: 19.6% • Both: 3.4%

  30. Precision:100% Recall:92% 11 Testing Set 12 92%(11) 3 100%(5) 100%(5) Training Set 5 Top Table Location Linked Pages Experimental Results − Table Location Cell-phone sales application domain

  31. Experimental Results − Mapping Cell-phone sales application domain • 11 recognized tables in the testing Set • Total 97 mappings • Precision: 90.1% Recall: 85.4% • Top-level tables: 85.4% of the 88 correct mappings • Linked tables: 50.5% • Both: 35.9%

  32. Contribution • Provides an approach to extract information automatically from HTML tables • Suggests a different way to solve the problem of schema matching

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