Hi ROOT'ers,
From: "Hans Wenzel (lokal)" <wenzel@fnal.gov>
Subject: selection in copytree
Date: Wed, 01 Mar 2000 17:41:03 +0100
Message-ID: <38BD481F.D6A8A317@fnal.gov>
wenzel> hi
wenzel> would be nice if one could pass a logical function as an argument in
wenzel> CopyTree. E.g. in the example below i don't like the fact that i have to
wenzel> hardwire the cut values where i would like to use variables. In addition
wenzel> the selection might become more complicated.
wenzel>
wenzel> newtree =t->fTree->CopyTree("Chiprob>0.01&&Mass>5.129&&Mass<5.429");
In fact, it would be nice, if you could do SQL queries on a tree. The
`TTreeResult' and `TTreeRow' classes are already there, so I guess a
`TTreeServer' class, with a `Query()' method, is all that's needed!
Ofcourse this isn't trivial, since one would have to write a SQL
parser and lexer (I did plan to do this at some point, but gave up,
since I couldn't find any bison (or yacc) gramma anywhere, and didn't
have the time anyway - sorry!).
Anyway, that's my two pennies worth.
Christian -----------------------------------------------------------
Holm Christensen Phone: (+45) 35 35 96 91
Sankt Hansgade 23, 1. th. Office: (+45) 353 25 305
DK-2200 Copenhagen N Web: www.nbi.dk/~cholm
Denmark Email: cholm@nbi.dk
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