[jira] Commented: (MATH-473) Frequency: new option: NON-sorted

["Patrick Meyer (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MATH-473?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12981240#action_12981240 ] 

Patrick Meyer commented on MATH-473:
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I think you might encounter problems with the cumulative count and percentages if there is no sorting. Your data may only be nominal and thus have no need for sorting, but I think the changes would require more than switching between a TreeMap and HashMap. Specifically, thought would need to be given to the cumulative count and percentage methods. In terms of performance, I don't think there would be a perceptible difference between a TreeMap and a HashMap.

Also, I think you could simply write your own class that implements the comparable interface. That way you could define any type of sorting you would like.

> Frequency: new option: NON-sorted
> ---------------------------------
>
>                 Key: MATH-473
>                 URL: https://issues.apache.org/jira/browse/MATH-473
>             Project: Commons Math
>          Issue Type: Improvement
>            Reporter: Dan Checkoway
>
> I have a request for enhancement on org.apache.commons.math.stat.Frequency.  I would like to be able to specify that the the backing map NOT be sorted.  Right now it uses TreeMap.  I would like to have the option of specifying that sorting is not important, and would in fact hinder performance, and a plain old HashMap should be used instead.
> i.e. constructor such as:
> public Frequency(boolean sorted);
> If sorted is true, use a TreeMap.  If sorted is false, use a HashMap.  Is this feasible?  I'd be happy to contribute a patch if that would help.

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