How to divide a root ntuple file into several subfiles?

ROOT
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1

Hi experts,

I know we can use hadd command to merge several root files into one file. So whether there is a command can divide a very big root file into several subfiles. I have a very big root files, if i submit a job ,then it will cost much time. So I want to divide it into several subfiles.

Thank you!

2

On the terminal, check out:

user@pc:~$ rooteventselector --help

Use the “first” and “last” options to specify how many events in each part. E.g. if you want 10 events from the tree “mytree” per file:

$  rooteventselector -l 9 original.root:mytree new1.root
$  rooteventselector -f 10 -l 19 original.root:mytree new2.root

“last = 9” will include from event 0 to 9, i.e. 10 events, and so on.

3

Thank you!