Stl::vector in a tree

ROOT
1

Hi,
I’ve got a question concerning stl::vectors which are stored in a tree. I managed to create a TTree, where one branch is a vector. The result looks like this:

 root [39] t->Scan()
***********************************
*    Row   * Instance *         v *
***********************************
*        0 *        0 *       0.1 *
*        0 *        1 *       0.2 *
*        0 *        2 *      0.23 *
*        1 *        0 *       0.1 *
*        1 *        1 *       0.2 *
*        1 *        2 *      0.23 *
*        1 *        3 *      0.42 *
***********************************

Surprisingly not the vector class, but a list of the contents is stored in the tree. Because of this thigs like t->Draw(“v.size()”) are not possible.
Is there a way to get the length of the vector for each event, or event better to store the lenght of the vector in a separate branch when filling the tree?

Cheers, J.

2

[quote]but a list of the contents is stored in the tree. [/quote]Yes, this is the intend (we assume that this usually what you are interested in).

You can see all the details at root.cern.ch/root/html/TTree.html#TTree:Draw

Cheers,
Philippe

3

Thanks, this is what I was looking for…
Cheers, J.