Sum weights in TTree

ROOT
1

What is the recommended way to retrieve the weighted number of entries in a TTree?

I could, for example, do

nEntEffective = sum(ent.SomeWeight for ent in t if ent.SomeBranch > SomeCutValue)

but I wondered if I had overlooked some utility function a la t.GetEntries('SomeBranch > SomeCutValue') that would take weights into account.

ROOT Version: 6.19/01
Platform: macOS
Compiler: Not Provided

2

Hi,
maybe

df.Filter("x > y").Sum("weight")

?

3

Thank you. From my cursory study, these methods appear comparably fast if one has to make the data frame (i.e., RDataFrame(t).Filter('SomeBranch > SomeCutValue').Sum('SomeWeight')), while the data frame method appears much faster if one has already created the filtered data frame (df.Sum('SomeWeight')).

4

See this thread, the event loop is much faster with RDF, but for small datasets you’ll spend most of the time setting up RDF.