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You already encountered one of these get functions in the very first example where you were extracting the event identifier. The type field indicates what kind of data you are accessing, the source field indicates the instance of that particular detector. In this example there are two acqiris digitizers with the same data type. Note that event components obtained through this API will be objects of various classes. A full catalog of those objects can be found in the DOXYGEN documentation which is auto-generated from the code of the OFFLINE releases.

Iterating over

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stepsand events

Some of our experiments (in particular XPP) are heavily relying on so called scans steps, which are also known as Calibration Transitions. Each DAQ run has one or many scanssuch steps. Events are recorded in a scope of a scanparticular step. The new framework has a special provision for scans through the iterator of scanssteps. The idea behind the following example is:

• Open a data set which has multiple scans steps in each run
• Iterate over scanssteps
• Iterate over events in each scanstep

This simple application knows about scan step boundaries. More over, this example illustrates how to open a data set composed of many runs (processing a series of runs at once). There are two examples in this set:

./scanssteps_in_runs_xtc.py
./scanssteps_in_runs_hdf5.py

 These two scripts perform the same processing, the only difference being which data format they're accessing. The first example will read XTC files, while the second one will read HDF5 files. When running these examples you will notice that the HDF5 version is significantly faster. This is due to the fact that we don't yet support indexing for XTC files.

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