How do I copy a leaf from many ROOT files into one?


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I have several hundred ROOT files, all with the same Tree structure. They all have a leaf, let’s call it “myNum”. I want to iterate over all of the files, and put all of these “myNum” leaf values into one ROOT file. I’m seems that somehow I could use CloneTree() or CopyTree() to do this, but I’m entirely new to ROOT and I’m not sure how. What’s the most efficient way?

Hello,

For copying only some leafs into a new tree, have a look at the copytree.C tutorial. Instead of a single input tree, you can concatenate several trees using a TChain.

Cheers,
Jakob