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https://issues.apache.org/jira/browse/MATH-1205?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thomas Neidhart updated MATH-1205:
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Attachment: MATH-1205.patch
Attached a patch with the following changes:
* added class AbstractCachingUnivariateStatistic which extends
AbstractUnivariateStatistic and contains the storedData field and corresponding
methods
* Percentile extends now AbstractCachingUnivariateStatistic
* fix AbstractStorelessUnivariateStatistic#evaluate(double[], int, int) method
to be consistent with the other implementations: it does not alter the internal
state anymore, but instead creates first a copy of the current statistic and
the calls clear() and incrementAll() on the copy instead.
* fix AbstractStorelessUnivariateStatistic#equals(Object): the equality check
will only succeed for statistics of the same class. This might be useful,
although I am not 100% sure, we might also just remove the default
equals/hashCode.
* fix Variance#evaluate(...) methods: they altered the internal state by
calling clear(), although the javadoc stated the opposite.
If preferred, I can also make separate issues for the bullets, currently the
changes.xml contains separate entries for all of them, but without a ticket
number.
btw. the storedData fields and methods have been introduced in MATH-417 to
improve the performance of the Percentile class, but have not been used for any
other class.
> AbstractStorelessUnivariateStatistic should not extend
> AbstractUnivariateStatistic
> ----------------------------------------------------------------------------------
>
> Key: MATH-1205
> URL: https://issues.apache.org/jira/browse/MATH-1205
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.4.1
> Reporter: Thomas Neidhart
> Attachments: MATH-1205.patch
>
>
> For a storeless statistic it is wrong to extend AbstractUnivariateStatistic
> as various fields and methods are inherited that do not make sense in case of
> a storeless statistic.
> This means a user can accidentially use a storeless statistic in a wrong way:
> {code}
> Mean mean = new Mean();
>
> mean.increment(1);
> mean.increment(2);
>
> mean.setData(new double[] { 1, 2, 3});
>
> System.out.println(mean.getResult());
> System.out.println(mean.evaluate());
> {code}
> will output
> {noformat}
> 1.5
> 2.0
> {noformat}
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