Jeff Patterson writes: > Hey Rooters, > > My problem is that my histrograms keep disappearing from memory. > Here is what I am doing. I have an row-wise Ntuple from HBook that I have > converted with h2root. The ntuple is called h666. So I open the file, > make the histogram, then I want to clode the Ntuple and open another one > and add to it. But as soon as I close the file, I lose the histogram. > How can I get around this. Sample code > > f1 = new TFile("ntup1"); > MOM = new TH1F(bins); > h666->Draw("mom>>+MOM", "cuts"); > delete f1 //This is were I lose my histogram > f1 = new TFile("ntup2"); > MOM = new TH1F(bins); > h666->Draw("mom>>+MOM", "cuts"); > etc..... > > What am I doing wrong. > > Jeff Patterson > Jeff: when you create a histogram after haaving opened a file, ROOT associates it with this file, so when you delete the file, your histogram also gets deleted. If you don't want to save `h666' into a file, simple inversion MOM = new TH1F(bins); f1 = new TFile("ntup1"); will do the job and your histogram will remain in memory after you close `f1'. - regards, pasha.
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