Re: Drawing objects in a file

With your example you should at least get your TH2F object drawn. To draw the graphs you must specify a draw option, eg "alp" (default for the browser).

Rene Brun

On 28/04/2011 00:37, Stephan Zimmer wrote:
> Hi Rooters,
> suppose I have a file that contains a number of objects (which I cannot
> really influence):
> root [1] .ls
> TFile** temp.root
> TFile* temp.root
> OBJ: TH2F hist0 : 0 at: 0xaa08418
> KEY: TH2F hist0;1
> KEY: TGraphErrors Graph;44 Graph
> KEY: TGraphErrors Graph;43 Graph
> KEY: TGraphErrors Graph;42 Graph
> KEY: TGraphErrors Graph;41 Graph
> KEY: TGraphErrors Graph;40 Graph
> KEY: TGraphErrors Graph;39 Graph
> KEY: TGraphErrors Graph;38 Graph
> KEY: TGraphErrors Graph;37 Graph
> KEY: TGraphErrors Graph;36 Graph
> KEY: TGraphErrors Graph;35 Graph
> KEY: TGraphErrors Graph;34 Graph
> KEY: TGraphErrors Graph;33 Graph
> KEY: TGraphErrors Graph;32 Graph
> KEY: TGraphErrors Graph;31 Graph
> KEY: TGraphErrors Graph;30 Graph
> KEY: TGraphErrors Graph;29 Graph
> KEY: TGraphErrors Graph;28 Graph
> KEY: TGraphErrors Graph;27 Graph
> KEY: TGraphErrors Graph;26 Graph
> KEY: TGraphErrors Graph;25 Graph
> KEY: TGraphErrors Graph;24 Graph
> KEY: TGraphErrors Graph;23 Graph
> KEY: TGraphErrors Graph;22 Graph
> KEY: TGraphErrors Graph;21 Graph
> KEY: TGraphErrors Graph;20 Graph
> KEY: TGraphErrors Graph;19 Graph
> KEY: TGraphErrors Graph;18 Graph
> KEY: TGraphErrors Graph;17 Graph
> KEY: TGraphErrors Graph;16 Graph
> KEY: TGraphErrors Graph;15 Graph
> KEY: TGraphErrors Graph;14 Graph
> KEY: TGraphErrors Graph;13 Graph
> KEY: TGraphErrors Graph;12 Graph
> KEY: TGraphErrors Graph;11 Graph
> KEY: TGraphErrors Graph;10 Graph
> KEY: TGraphErrors Graph;9 Graph
> KEY: TGraphErrors Graph;8 Graph
> KEY: TGraphErrors Graph;7 Graph
> KEY: TGraphErrors Graph;6 Graph
> KEY: TGraphErrors Graph;5 Graph
> KEY: TGraphErrors Graph;4 Graph
> KEY: TGraphErrors Graph;3 Graph
> KEY: TGraphErrors Graph;2 Graph
> KEY: TGraphErrors Graph;1 Graph
> root [2]
>
> I'm wondering why the following method of accessing the elements in a
> file does not work:
>
> TFile *f = new TFile("temp.root","r");
> TIter nextkey(f->GetListOfKeys());
> TKey *key;
> while (key = (TKey*)nextkey()) {
> TObject *obj = (TObject*)key->ReadObj();
> obj->Draw();
> }
>
> it doesn't complain but it doesn't show anything either. On the other
> hand, if i open the same file with the TBrowser it draws without
> complaints. As for the reference, I'm using Root 5.27/06 Could someone
> be so kind and help me figuring out what's going on here?
>
> Cheers and thanks,
> Stephan
Received on Thu Apr 28 2011 - 08:20:43 CEST