578 Chapter 10. Software for Data Analysis
As the name suggests, the TBrowser window is a platform where the whole ROOT
file can be browsed. The browser shows not only the current directory and the
root directory but also a directory calledROOT Files, where the ROOT file being
browsed exists. Note that ROOT does not create any new physical directory, rather
loads the file to a location in the TBrowser’s memory (see Fig.10.1.2). When one
clicks twice on a ROOT file in any physical directory, the file is loaded into the
ROOT Files location from where it can be browsed.
Figure 10.1.2: When a ROOT file is clicked twice in any directory, the TBrowser
loads it into the ROOT Files location.
Clicking twice the ROOT file in the ROOT Files location expands it into objects
as shown in Fig.10.1.3.
The individual objects can then be clicked twice for examination. For example,
Fig.10.1.4 shows the histogram that was obtained by double clicking the first icon
in Fig.10.1.3. In the example shown the ROOT file contains only a few histograms.
However the design of ROOT allows it to contain any allowed object. It can even
containtreesas mentioned earlier.
The tree structure is a generalization of thentuplestructure, which contains only
floating point numbers. A tree, on the other hand, may consist of many objects, such
as histograms and arrays. The advantage of saving the data and analyses in a tree
structure is that it makes further access and processing of the data very fast. The
faster speed is a consequence of the way tree structure has been designed. It has a
hierarchical structure consisting of leafs, branches, and buffers. These objects can be
accessed independently of other similar objects in a tree and therefore reprocessing
does not require the whole data to be accessed.