df031_Stats.C File Reference

Detailed Description

Use the Stats action to extract the statistics of a column.

Extract the statistics relative to RDataFrame columns and store them in TStatistic instances.

 
void df031_Stats() {
 
    // Create a data frame and add two columns: one for the values and one for the weight.
    ROOT::RDataFrame r(256);
    auto rr = r.Define("v", [](ULong64_t e){return e;}, {"rdfentry_"})
               .Define("w", [](ULong64_t e){return 1./(e+1);}, {"v"});
 
    // Now extract the statistics, weighted, unweighted - with and without explicit types.
    auto stats_eu = rr.Stats<ULong64_t>("v");
    auto stats_ew = rr.Stats<ULong64_t, double>("v", "w");
    auto stats_iu = rr.Stats("v");
    auto stats_iw = rr.Stats("v", "w");
 
    // Now print them: they are all identical of course!
    stats_eu->Print();
    stats_ew->Print();
    stats_iu->Print();
    stats_iw->Print();
}

 
 OBJ: TStatistic      Mean = 127.5 +- 4.628   RMS = 74.045   Count = 256    Min = 0     Max = 255
 OBJ: TStatistic      Mean = 40.8 +- 12.86    RMS = 60.318   Count = 256    Min = 0     Max = 255
 OBJ: TStatistic      Mean = 127.5 +- 4.628   RMS = 74.045   Count = 256    Min = 0     Max = 255
 OBJ: TStatistic      Mean = 40.8 +- 12.86    RMS = 60.318   Count = 256    Min = 0     Max = 255

Date

April 2019

Author

Danilo Piparo (CERN)

Definition in file df031_Stats.C.