Unstable results when enabling MT and filling a THnD histogram using Take

[Javier_Galan]

Dear @eguiraud, in origin my problem was about filling a THnSparse object. There is another post about this here:

Filling a THnD or THnSparse using `Draw` or `RDataFrame`

I am having a look to the documentation of classes THnD and THnSparse. I see in the documentation that this objects are filled as a traditional TH1D histogram, using Fill. So I could just iterate and fill. But there is a more straight forward way to do this? I see for example inside RDataFrame there is a method .HistoND that I imagine it returns a THnD. However, how could I initialise a THnSparse object that seems to be more suited for data with many zeros? If I try: auto hN = dataFrame.Hist…

So, in origin I was working with an THnSparse and while trying to make it work I thought it would be good to try with a THnD. I need to use a THnX so that I can in future use any number of variables.

EDIT: I see now that perhaps the solution in previous post is that I need to use THnSparseD and not the abstract class THnSparse!

I imagine the @mczurylo example will also work with THnD without problems, but the point is that I want to be able to fill in a THnSparse to be more memory efficient, and I think this is only possible with a manual fill?

I got other issues with THnSparse, see post:

Problems using THnSparse Projection

Hi there! I am using the following macro, where I am accessing a RDataFrame to generate histograms of final_posX and final_posY column names by different methods. When I draw using df.Histo1D, THnSparse::Draw or THnSparse::Projection(0,1)->Draw() I get different results.

C-macro

Int_t test( std::string fname ) { TRestDataSet dS; dS.Import(fname); dS.PrintMetadata(); auto myHist1 = dS.GetDataFrame().Histo2D({"histName", "histTitle", 80u, -20, 20, 80u, -20., 2…

Thanks for your replies!