|STAR Computing||Tutorials main page|
|Grid Collector Tutorial|
|Offline computing tutorial||Maintained by John Wu|
This is a short tutorial explaining the key steps to use Grid Collector (GC) software for STAR offline analysis. If you are using computers at RCF (BNL) or PDSF (NERSC), this should get you started. To go further, you might want to look at the longer version. Feel free to contact the maintainer of Grid Collector with your questions or comments.
ATTENTION: The GridCollector rely on both tags and a bitmap index to be build. If it is not in place, this tool will not work.
root4star -b -q doEvents.C'(25,"select MuDst where Production=P04ie \ and trgSetupName=production62GeV and magScale=ReversedFullField \ and chargedMultiplicity>3300 and NV0>200", "gc,dbon")'It selects and analyzes 25 out of 1.2K events in two MuDst data files. Its output message is saved in P04ie_GC.log which may be helpful in understanding how GC works.
The basic syntax of a Grid Collector command is
[SELECT fileTypes [additional options]] WHERE condtionsThe statment is not case sensitive. As usual, the content inside square brackets '' is optional. If the select clause is ommited, "SELECT event" is assumed. For more explanation of the syntax of the select statement used above, please refer to the long tutorial. In addition to 'production', 'trgSetupName' and 'magScale', the names appeared in tags.root files can also be used. Tags from different productions are different, here is a list of names available in a recent production named P05ia.
Analysis macros that use StIOMaker typically define a StFileI* variable, for example,
StFileI* setFiles = new StFile("files");To use GC, simply initialize the same variable with StGridCollector::Create() as follows,
StFileI* setFiles = StGridCollector::Create("select ...");The variable setFiles can be used in the creation of StIOMaker as usual.