Re: [ROOT] Re: Getting TDirectory entries with pyROOT

From: Rene Brun (brun@pcbrun.cern.ch)
Date: Wed Jun 30 2004 - 23:07:09 MEST


To see the list of objects (with name and title) in the current 
directory, do:
   gDirectory->ls()

this iterates on the list of Tkeys and for each TKey shows the name and 
title.

Rene Brun

On Wed, 30 Jun 2004 WLavrijsen@lbl.gov wrote:

> Topher,
> 
> >  How do I gracefully check for a null TObject pointer in pyroot?
> 
> Use a boolean predicate, or if you want to turn it into a boolean value, use
> the 'not not' trick. That is, from your example:
> 
> >>> this = tdir.Get("h400")
> >>> print not not this
> 1
> >>> that = tdir.Get("h401")
> >>> print not not that
> 0
> >>> if that:
> ...   that.GetName()
> ...
> >>>                                # <- nothing, as 'that' evaluates to False
> 
> The assertion will be removed. You are quite right that an exception would
> be far more appropriate. But that'll be for a later release.
> 
> >  How can I get the name (and title) of an object in a file without reading
> > the whole thing into memory?
> 
> Isn't that a general ROOT question? I'll have a look into it later, but I need
> to warn you that I know next to nothing of using ROOT, so I may not find an
> answer.
> 
> HTH,
>   Wim
> 



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