[MAHOUT-945] The variance calculation of Random forest regression tree

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.6
• Fix Version/s: 0.8
• Labels: Regressionsplit.java
• Assignee: Sean R. Owen
• Reporter: Wang Yue
• Created: 11/Jan/12 12:00
• Updated: 31/Jan/24 22:12
• Resolved: 12/Mar/13 23:14

Description

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

Issue Links

• relates to: MAHOUT-943 Improbe the way to make the split point on DF.