Github user yinxusen commented on the pull request:

    https://github.com/apache/spark/pull/458#issuecomment-41148756
  
    @coderxiang I do some experiments on your dataset.
    * For MLlib, you should first rewrite your labels {+1, -1} into {+1, 0}. 
[Reference 
here](http://54.82.240.23:4000/mllib-linear-methods.html#binary-classification)
    * For Lasso, you need preprocess your dataset, and make it with zero mean 
and unit norm. [Reference 
here](http://stats.stackexchange.com/questions/19523/need-for-centering-and-standardizing-data-in-regression).
 @mengxr just removed the former preprocessing because it is not elegant.
    
    I open a [JIRA issue](https://issues.apache.org/jira/browse/SPARK-1585) to 
explain the reason why `Infinity` occurs. IMHO, I prefer rewriting [this line]( 
https://github.com/apache/spark/blob/master/mllib/src/main/scala/org/apache/spark/mllib/optimization/Gradient.scala#L127)
 into
    
    `brzAxpy(2.0 * diff / weights.size, brzData, cumGradient.toBreeze)`
    
    to do average, since the gradient is used for updating each single element 
of weights. But I am not sure of that, maybe @mengxr and @etrain could give us 
some suggestions.


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