ABCDEFGHIJKLMNOPQRSTUVWXYZ
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Tf-Idf Definition and Example
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Term Frequency (TF): TF(t) = (Number of times term t appears in a document) / (Total number of terms in the document)
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Inverse Document Frequency (IDF): IDF(t) = log_e(Total number of documents / Number of documents with term t in it)
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It helps to find out relevant documents for the query
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Example: There are 3 different documents in the collection (dataset)
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Q1.Find TF and IDF
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Q2.
For the query Q = "Big Data", find the two top ranked documents according to the TF/IDF rank
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Solution Q1: TF and IDF
ITstudyBigData
prediction
helpsin
business
Total Terms in a doc
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d1:IT study Big DataTF for d111114
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d2:
Big Data helps in big prediction
TF for d2211116
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d3:
Big prediction helps in business
TF for d3111115
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# of docs with term =
1132222114
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Inverse Document Frequency (IDF)
IDF =
log(# docs / # docs with that term)
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IDF = 0.4770.4770.0000.1760.1760.1760.1760.477
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