using root is a lesson in limitation: whatever it is you want to do
probably isn't an option. instead, you'll have to think of an ingenius
way to do whatever it is you want with the existing options. for example,
in order to plot the following:
atl/atr, if acl>0
atr/atl, else
you could type the following:
lr->Draw("(acl>0)*atl/atr + (1-(acl>0))*atr/atl");
logical conditions, such as "acl>0" evaluate to either 1 (true) or else 0
(false).
there is probably an even more clever way to do conditional plots on the
same axis, but i don't know it. and, of course, the above conditional
method gets real old real quick if you have loooonng strings you are
typing in.
aaron
On Wed, 23 Jul 2003, Kevin McIlhany wrote:
> I have been trying to start an analysis and was
> hoping to find the same functionality I used to have
> when using PAW, namely, the ability to manipulate a
> "user function" in an ntuple.
> Normally, one might draw a variable such as:
> lr->Draw("acr")
> I was hoping to have a function I could treat as an ntuple variable
> which is made up from the lr ntuple variables, such as:
> lr->Draw("myfunc.cc","myfunc.cc>10")
>
> While looking on the web, I saw references to this discussion on
> RootTalk about one year ago, with Rene Brun promising that this
> functionality would be implemented in a newer version. My question
> is...
> Has anyone achieved this at BLAST and if so, how?
> I assume we are using Root v3.02c, but even the release notes for
> v3.03/9b do NOT indicate that user functions have been added yet (at
> least they dont mention it!).
> Any thoughts?
>
> Also, in another attempt at finding something of a similar
> functionality, I found a reference to a function called MakeCode().
> Unfortunately, there is virtually no documentation that I could find on
> the web regarding this code, but it is CLAIMED that this is capable of
> making a user function. Any ideas? Has anyone successfully used this
> capability? If so, how?
>
>
> I could really use this capability as it would allow me to make a
> conditional variable in the ntuple, such as:
>
> f= atl/atr if acl>0
> else
> f= atr/atl
>
> lr->Draw("f")
>
> something like that would be useful.
>
> -Kevin
>
>
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