TChain - select entries only in a given file name(s)

ROOT
1

Hello,

suppose we have:

TChain chain("T"); chain.Add("file1.root"); chain.Add("file2.root"); chain.Add("file3.root");

  1. Is it possible to make a plot just for entries in e.g. “file2.root” (i.e. skipping entries from the other two files)? Something like:

where the TCut would select only the entries from a given file name.

  1. Is it possible to mask (temporary dissable/remove) some files which were added to a TChain such that they would not be taken into acount for looping over “all” entries? I can e.g. find all files added to a TChain and create a new TChain with just some files, but is there any other (recomended) way without creating an extra TChain?

Many thanks in advance.

Regards,
Jiri

2

Hi,

[quote]1) Is it possible to make a plot just for entries in e.g. “file2.root” (i.e. skipping entries from the other two files)? Something like:[/quote]You can use:chain.Draw("x:y", "This->GetCurrentFile()->GetName() == \"'file2.root\" "))however this is pretty ‘slow’ to get what you want.

[quote]2) Is it possible to mask (temporary dissable/remove) some files which were added to a TChain such that they would not be taken into acount for looping over “all” entries? [/quote]No. On the other hand, a TChain object is a pretty light weight object in itself so creating new TChain object is likely to be your best and simplest solution.

Cheers.
Philippe.

3

Hi Philippe,

ok, I’ll create new TChain if the first approch will be too slow. Many thanks for your fast reply!

Cheers,
Jiri