import ROOT
import numpy as np

filename = ROOT.gROOT.GetTutorialDir().Data() + "/analysis/dataframe/df017_vecOpsHEP.root"
treename = "myDataset"

def WithPyROOT(filename):
    from math import sqrt
    f = ROOT.TFile(filename)
    h = ROOT.TH1F("pt", "With PyROOT", 16, 0, 4)
    for event in f[treename]:
        h.Fill(
            np.array(
                [
                    sqrt(px * px + py * py)
                    for E, px, py in zip(event.E, event.px, event.py)
                    if E > 100
                ]
            )
        )
    h.DrawCopy()

def WithRDataFrameVecOpsJit(treename, filename):
    f = ROOT.RDataFrame(treename, filename)
    h = f.Define("good_pt", "sqrt(px*px + py*py)[E>100]")\
         .Histo1D(("pt", "With RDataFrame and RVec", 16, 0, 4), "good_pt")
    h.DrawCopy()

## We plot twice the same quantity, the key is to look into the implementation
## of the functions above.
c = ROOT.TCanvas()
c.Divide(2,1)
c.cd(1)
WithPyROOT(filename)
c.cd(2)
WithRDataFrameVecOpsJit(treename, filename)
c.SaveAs("df017_vecOpsHEP.png")

print("Saved figure to df017_vecOpsHEP.png")