This is where the TTree takes advantage of compression and will produce a much smaller file than if the objects were written individually. Branches, buffers, and leafs, are explained a little later in this chapter, but for now, it is important to realize that each object is not written individually, but rather collected and written a bunch at a time. When using a TTree, we fill its branch buffers with leaf data and the buffers are written to disk when it is full. A TNtuple is a TTree that is limited to only hold floating-point numbers a TTree on the other hand can hold all kind of data, such as objects or arrays in addition to all the simple types. The TTree class is optimized to reduce disk space and enhance access speed. In case you want to store large quantities of same-class objects, ROOT has designed the TTree and TNtuple classes specifically for that purpose. In the “Input/Output” chapter, we saw how objects can be saved in ROOT files. If you think some information should be imported in the ROOT Reference Guide or in the ROOT Manual, please post your request to the ROOT Forum or via a Github Issue. Instead please refer to the ROOT Reference Guide and the ROOT Manual. Some part might be obsolete or wrong, some part might be missing but still some valuable information can be found there. WARNING: This documentation is not maintained anymore. 14.20 Simple Analysis Using TTree::Draw.14.18 Example 5: Import an ASCII File into a TTree.14.17 Example 4: A Tree with an Event Class.14.16 Example 3: Adding Friends to Trees.14.15 Example 2: A Tree with a C Structure. 14.14 Example 1: A Tree with Simple Variables.14.13 Examples for Writing and Reading Trees.14.12 Adding a Branch with a Collection. 14.10 Adding a TBranch to Hold an Object.14.9 Adding a Branch to Hold a List of Variables.14.5 Scan a Variable the Tree with TTree::Scan.14.4 Print the Tree Structure with TTree::Print.
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