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https://issues.apache.org/jira/browse/SPARK-19234?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15827236#comment-15827236
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Andrew MacKinlay edited comment on SPARK-19234 at 1/18/17 1:53 AM:
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[~yanboliang] I presume that you are the author judging by Github commits? Do 
you have an opinion on this? 


was (Author: admackin):
[~yanbo] I presume that you are the author judging by Github commits? Do you 
have an opinion on this? 

> AFTSurvivalRegression chokes silently or with confusing errors when any 
> labels are zero
> ---------------------------------------------------------------------------------------
>
>                 Key: SPARK-19234
>                 URL: https://issues.apache.org/jira/browse/SPARK-19234
>             Project: Spark
>          Issue Type: Bug
>          Components: ML
>    Affects Versions: 2.1.0
>         Environment: spark-shell or pyspark
>            Reporter: Andrew MacKinlay
>            Priority: Minor
>         Attachments: spark-aft-failure.txt
>
>
> If you try and use AFTSurvivalRegression and any label in your input data is 
> 0.0, you get coefficients of 0.0 returned, and in many cases, errors like 
> this:
> {{17/01/16 15:10:50 ERROR StrongWolfeLineSearch: Encountered bad values in 
> function evaluation. Decreasing step size to NaN}}
> Zero should, I think, be an allowed value for survival analysis. I don't know 
> if this is a pathological case for AFT specifically as I don't know enough 
> about it, but this behaviour is clearly undesirable. If you have any labels 
> of 0.0, you get either a) obscure error messages, with no knowledge of the 
> cause and coefficients which are all zero or b) no errors messages at all and 
> coefficients of zero (arguably worse, since you don't even have console 
> output to tell you something's gone awry). If AFT doesn't work with 
> zero-valued labels, Spark should fail fast and let the developer know why. If 
> it does, we should get results here.



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