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1

Dear developers,

I would like to create an array of histograms (of variable length). Then after having created this array I would like to look for elements in it using histo name.

Using STL, I could do :
std::map hmap;
hmap[“h1”] = new TH1F(…);
hmap[“h2”] = new TH1F(…);
and filling histos like that
hmap[“h1”]->Fill(x1);
…
however std::map do not seem to work in interactive root sessions. Could you confirm ?

So an alternative solution could be to use a std::vector and a class method like GetHisto(TString histoname). But in this method I need to loop over vector elements to math names which is quite time consuming…

My question, do you have a quick alternative way to code that ?

2

Oups, of course I was meaning std::map( TString, TH1F )

ps: do not know why I cannot write text between lower than and greater than signs.

3

[quote=“renaud”]Oups, of course I was meaning std::map( TString, TH1F )
[/quote]

Hopefully you meant

std::map < TString, TH1F* >

I have used std::map < std::string, void* > histMap; and that seemed to work (I can’t remember why I used void* and then cast it to TH1F*…) in cint.
Charles

p.s. Rene just pointed out in another message that you can use '<'s if you click “Disable HTML in this post”

4

Hi,

You probably need to generate the dictionary for this stl container before being able to use it properly from the command line.

Cheers,
Philippe

5

[quote=“pcanal”]You probably need to generate the dictionary for this stl container before being able to use it properly from the command line.
[/quote]

You don’t need to if you want to use an interpreted script (at least not in Root 4). See attached script.
histWithMap.C (5.16 KB)