Stripping Data
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Stripping data means removing removing streams from going to the output file. It will cause all data from specified locations in the event stores to not be saved. See also Pruning Data and Filtering Data.
Strip with explicit output streams
To strip data one tells NuWa explicitly what output streams go to what files. You can either save the unwanted streams to a file and then discard that file or you can not save the streams at all.
It is very important to save the special RegistrationSequence stream. This will need to be present in an input stream to read back any other stream into NuWa.
To specify an explicit map from stream to file you use the -O option to nuwa.py.
nuwa.py -O '/Event/RegistrationSequence:output.root /Event/Readout/ReadoutHeader:output.root' -o junk.root ...
This command would save only the RegistrationSequence and ReadoutHeader streams to "output.root". All other streams will be saved to the defauult "junk.root" which could be discarded if desired. You can also specify the default output file in the map itself using the special "default" stream name:
nuwa.py -O '... default:junk.root' ...
If no default is specified then any unnamed streams will not be saved. Note that this will lead to many "warning" level log message to be printed.
Achieving the same with the "smart filter"
See this topic for an alternate way to implement this same pattern.
See also
http://dayabay.bnl.gov/oum/analysis/nuwarecipes/#sec-filterpaths
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