[jira] [Commented] (SPARK-3614) Filter on minimum occurrences of a term in IDF

["RJ Nowling (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-3614?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14142631#comment-14142631 ] 

RJ Nowling commented on SPARK-3614:
-----------------------------------

I would like to work on this.

> Filter on minimum occurrences of a term in IDF 
> -----------------------------------------------
>
>                 Key: SPARK-3614
>                 URL: https://issues.apache.org/jira/browse/SPARK-3614
>             Project: Spark
>          Issue Type: Improvement
>          Components: MLlib
>            Reporter: Jatinpreet Singh
>            Priority: Minor
>              Labels: TFIDF
>
> The IDF class in MLlib does not provide the capability of defining a minimum number of documents a term should appear in the corpus. The idea is to have a cutoff variable which defines this minimum occurrence value, and the terms which have lower frequency are ignored.
> Mathematically,
> IDF(t,D)=log( (|D|+1)/(DF(t,D)+1) ), for DF(t,D) >=minimumOccurance
> where, 
> D is the total number of documents in the corpus
> DF(t,D) is the number of documents that contain the term t
> minimumOccurance is the minimum number of documents the term appears in the document corpus
> This would have an impact on accuracy as terms that appear in less than a certain limit of documents, have low or no importance in TFIDF vectors.



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