Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
I am using LETOR to make an information retrieval system. They use TF and IDF.
I am sure TF is query-dependent. But IDF should be to, but:
“Note that IDF is document independent, and so all the documents under a query have
same IDF values.”
But that does not make sense because IDF is part of the feature list. How will IDF for each document be calculated?
IDF is term specific. The IDF of any given term is document independent, but the TF is document specific.
To say it differently.
Let’s say we have 3 documents.
doc id 1
“The quick brown fox jumps over the lazy dog”
doc id 2
“The Sly Fox Pub Annapolis is located on church circle”
doc id 3
“Located on Church Circle, in the heart of the Historic District”
Now if IDF is (number of documents) / (number of documents containing term t)
then the IDF for the term fox is 3/2 regardless of what the search is or what the document is. So IDF is a function of t.
TF on the other hand is a funciton on t and d. So the TF of ‘the’ for doc id 1 is 2.