remage output files#

remage supports multiple output formats (ROOT, HDF5, …) if it had been compiled in. The file type to use is selected by the specified output file name.

The contents of the output files is determined by output schemes. An output scheme does not only contain functionality for the actual output description, but also might have parts of Geant4’s stacking action functionality. Output schemes, in general, are remage’s way to implement pluggable event selection, persistency and track stacking.

Selection of output schemes#

Adding a sensitive detector of any type will add the corresponding main output scheme to the list of active output schemes.

Additional output schemes might be used for filtering output. Optional output schemes can be enabled with the macro command /RMG/Manager/ActivateOutputScheme [name].

Adding output schemes with C++ code is possible using the RMGUserInit system of remage (access it with auto user_init = RMGManager::Instance()->GetUserInit():

  • user_init->AddOutputScheme<T>(...); adds and enables the output scheme new T(...) on each worker thread,

  • user_init->AddOptionalOutputScheme<T>("name", ...); adds a name-tag to an output scheme, that will not be enabled right away, and

  • user_init->ActivateOptionalOutputScheme("name") enables such a registered output scheme.

LH5 output#

It is possible to directly write a LH5 file from remage, to facilitate reading output ntuples as a LH5 Table. To use this feature, simply specify an output file with a .lh5 extension, and remage will perform the file conversion automatically.

Additionally, the standalone tool remage-to-lh5 is provided to convert a default Geant4 HDF5 file to a LH5 file. With this, executing remage -o output.lh5 [...] is roughly equivalent to the combination of commands:

$ remage -o output.hdf5 [...]
$ remage-to-lh5 output.hdf5
$ mv output.{hdf5,lh5}

Physical units in remage output#

Geant4 does not allow to attach metadata to columns. The ntuple columns created by remage contain physical units in their names, encoded as in the legend-metadata spec (i.e. adding _in_<units> at the end of the name), where the units are expressed in the typical physical unit symbols. Unfortunately, column names cannot contain forward slashes, so units lkike m/s are not possible to represent directly. Instead, a backslash (\) is used to encode the division symbol (for example: velocity_in_m\s).

This is not really helpful to any consuming application, so remage-to-lh5 does a back-transform of the backslashes to forward slashes, and also properly serializes the units as HDF5 attributes.