Re: [Jboost-users] Question regarding matlab output of classifier

[Aaron A. <aa...@cs...>]

Hi Viren,

The inverted label is a result of JBoost using it's own internal 
labeling system.  If you swap the order of how you specify the labels 
(i.e. instead of "labels (1,-1)" you do "labels (-1,1)") you'll get the 
correct label.

I haven't heard about the difference in score before.  Are you perhaps 
looking at the scores for the wrong iteration?  Are you using "-a -1" or 
"-a -2" switches to obtain the appropriate score/margin output files?  Are 
you perhaps getting training and testing sets mixed up?

I just tested ADD_ROOT on the spambase dataset (in the demo directory) and 
it looks like everything is fine.  If you can send your train/test files 
or reproduce the bug on the spambase dataset, please send me the exact 
parameters you're using and I'll see if it's a bug, poor documentation, or 
a misunderstanding of some sort.

Thanks for the heads up on the potential bug in the matlab scores.

Aaron



On Wed, 13 Aug 2008, Viren Jain wrote:

> I trained a LogLossBoost classifier with -ATreeType ADD_ROOT using 
> Jboost. I also asked it to output a matlab script I could use to 
> classify examples with in the future. However, I was wondering why the 
> matlab script outputs slightly different values than I would get by 
> classifying the training/test set directly using Jboost (for example, 
> the sign of the classifier output is always opposite to what Jboost 
> produces, and at most I have seen a 0.1469 discrepancy in the actual 
> value after accounting for the sign issue). Has anyone encountered this 
> issue, or am I perhaps doing something incorrectly?