TMVAMulticlass AddTree

TMVA
1

Dear experts,
I do not see why when I run my TMVAMulticlass (1) in the output I (2) see 4 background instead of 3 and it calls tha last one “Background” and it does not have any entries? Do you see what is wrong?
Regards

(1)
http://calpas.web.cern.ch/calpas/TMVAMulticlass.C

(2)
http://calpas.web.cern.ch/calpas/log_mva

2

Dear experts,
any ideas?
Regards

3

Try changing the name Signal to something else.

4

Dear Kialbert,
it does not change anything.
Regards

5

It’s because of SetBackgroundWeightExpression. In multiclass, this function should only be called with AnalysisType=Classification. (This could be made more clear). Because of this, the function assumes a class named “Background” will exist.

If you want to have the same weight expression for a number of classes, you have to specify it several times.

dataloader->SetWeightExpression("expr", "bg0");
dataloader->SetWeightExpression("expr", "bg1");
dataloader->SetWeightExpression("expr", "bg2");

Cheers,
Kim