[jira] [Commented] (TEXT-130) JaroWinklerDistance: Wrong results due to precision of transpositions

[ASF GitHub Bot (JIRA)]

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https://issues.apache.org/jira/browse/TEXT-130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16567516#comment-16567516
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ASF GitHub Bot commented on TEXT-130:
-------------------------------------

Github user coveralls commented on the issue:

    https://github.com/apache/commons-text/pull/87
  
    
    [![Coverage 
Status](https://coveralls.io/builds/18301471/badge)](https://coveralls.io/builds/18301471)
    
    Coverage remained the same at 97.833% when pulling 
**5d148549bc6ea8501016856547e27aed58b116c3 on jmkeil:master** into 
**802258f6370e4f9e12fb23ff2eb5f62c49011f13 on apache:master**.



> JaroWinklerDistance: Wrong results due to precision of transpositions
> ---------------------------------------------------------------------
>
>                 Key: TEXT-130
>                 URL: https://issues.apache.org/jira/browse/TEXT-130
>             Project: Commons Text
>          Issue Type: Bug
>            Reporter: Jan Martin Keil
>            Priority: Major
>
> The method {{JaroWinklerDistance#matches}} returns {{transpositions / 2}} as 
> integer. However, it is not granted for {{transpositions}} to be even. E.g. 
> comparing "aaabcd" and "aaacdb" will result in {{transpositions}} = 3. 
> Therefore the method must return 1.5, not 1. Otherwise the similarity is 
> 0.9611111111111111 instead of 0.9416666666666667.
> I recommend to return {{halfTranspositions}} instead of {{transpositions}} 
> and doing the cast and division ({{(double) mtp[1] / 2}}) in 
> {{JaroWinklerDistance#apply}}.



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