import ROOT

# Create the data frame
MakeTrivialDataFrame = ROOT.RDF.MakeTrivialDataFrame

nEvents = 128

d_s = MakeTrivialDataFrame(nEvents)

# Now we have a regular RDataFrame: the ingestion of data is delegated to
# the RDataSource. At this point everything works as before.
h_s = d_s.Define("x", "1./(1. + col0)").Histo1D(("h_s", "h_s", 128, 0, .6), "x")

c = ROOT.TCanvas()
c.SetLogy()
h_s.Draw()
c.SaveAs("df010_trivialDataSource.png")

print("Saved figure to df010_trivialDataSource.png")