R help - Nov 2007 - Questions on RWeka classifiers

Hi,

I am using some classifiers in RWeka packages and met a couple problems.

(1) J48 implements C45 classifier, the C45 should be able to handle missing
     values in both training set and test set. But I found the J48
classifier can
     not be evaluated on test set with missing values--it just ignore them.
(2) The ensemble classifiers in RWeka such as bagging and boosting: there
     is a control argument as "W" to describe which base classifier
should
be used.
     I use "W=J48" to boost C45 tree, but I am not sure how to down
size the
tree
    to be a "weak" learner. Based on what I observed, the default
boosted
J48 tree
    gets worse performance.

Thanks for any discussion and help,

Li

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