Hi Miro,
You can do something like:
tree.Draw("varx:vary","selection","goff",0);
then use the result of the TTreeFormula objects created above
tree->GetVar1,2,3, etc
Rene Brun
On Mon, 24 Jun 2002, Miroslav Helbich wrote:
>
> Hi all and developers,
>
> is there any way to figure out if the variable expression and data
> selection string are O.K. in
>
> TTree::Draw(const char* varexp, char* selection, Option_t* option, Int_t
> nentries= 1000000000, Int_t firstentry = 0)
>
> and what dimensional histogram is going to be drawn?
>
> I am sometimes writing the classes which pass this arguments
> from user (or are created inside the code). Is there any way to figure out
> if this will perform O.K. before passing this to the TTree::Draw()?
>
> There must be some parsing already coded in.
>
>
> If not than maybe some functions like the following would be useful.
>
> bool CheckSelection(char* selection)
> int CheckVarexp(char* varexp)
> // return 0 if wrong
> // return 1 if 1 dim histogram is drawn
> // return 2 if 2 dim histogram is drawn
> // return 3 if 3 dim histogram is drawn
> + some other variables depnding on wheter it is going to be draw to
> predefined histogram Draw("Energy>>histo") or to event list etc.
>
> Miro Helbich
>
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