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https://issues.apache.org/jira/browse/MAHOUT-838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13139712#comment-13139712
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Ted Dunning commented on MAHOUT-838:
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No. I think both of those issues (LinkedHashMap and bad rounding) are
black-ball issues.
They are going to have to be fixed eventually. Might as well be now.
For explanation, the principle behind the data type issue is that the declared
type of a variable should be the weakest type possible to allow more
polymorphism and freedom of implementation in other places. For instance, List
arguments should be Iterable if possible instead of List or ArrayList and Map's
should be Maps rather than HashMap or LinkedHashMap unless there is a *really*
strong reason otherwise.
For the rounding, it is simply a matter of correctness. Adding a small number
and then truncating is just not right. THis is due to a number of reasons, but
the short form reason is that floating point arithmetic is more complicated
than it looks. Doing rounding right in all the corner cases is harder than it
looks and doing it wrong leads to code that behaves in very surprising and bad
ways; these corner cases are they way they are in floating point math for very
good reasons.
> Make the confusion matrix writable to a file when testing classifiers
> ---------------------------------------------------------------------
>
> Key: MAHOUT-838
> URL: https://issues.apache.org/jira/browse/MAHOUT-838
> Project: Mahout
> Issue Type: Improvement
> Affects Versions: 0.6
> Reporter: Grant Ingersoll
> Priority: Minor
> Attachments: ConfusionMatrix.java, MAHOUT-838.patch,
> MAHOUT-838.patch, MAHOUT-838.patch, MAHOUT-838_mini.patch,
> MatrixWritable.java, bayes-cm-10.html
>
>
> If you have a lot of labels for a classifier, the confusion matrix is hard to
> fit in terminal window. Would be nice if we could write it out to a file.
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