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https://issues.apache.org/jira/browse/MAHOUT-943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13184004#comment-13184004
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Wang Yue commented on MAHOUT-943:
---------------------------------
Hi, Mukai
Thanks for your efforts in expand the RF to regression. However, I have a
doubt about your implementation regarding to Regressionsplit.java. The variance
method
"
private static double variance(double[] s, double[] ss, double[] dataSize) {
double var = 0;
for (int i = 0; i < s.length; i++) {
if (dataSize[i] > 0) {
var += ss[i] - ((s[i] * s[i]) / dataSize[i]);
}
}
return var;
}
"
While the variance in my mind should be something like
var += ss[i]/dataSize[i] - ((s[i] * s[i]) / dataSize[i]*dataSize[i]);
Please help correct me if I am wrong. Thanks
> Improbe the way to make the split point on DF.
> ----------------------------------------------
>
> Key: MAHOUT-943
> URL: https://issues.apache.org/jira/browse/MAHOUT-943
> Project: Mahout
> Issue Type: Improvement
> Components: Classification
> Reporter: Ikumasa Mukai
> Labels: DecisionForest
>
> The numericalSplit() on OptIgSplit adopts the way to regard the attribute
> value having the best IG as the split point.
> But I think this is a little too strict and think it is better on some
> situation to use the average value which is calced with the best IG value
> and the 2nd value.
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