This tutorial shows how to fill a TGraph using the Dataframe.
import ROOT
ROOT.ROOT.EnableImplicitMT(2)
d = ROOT.ROOT.RDataFrame(160)
# Create a trivial parabola
dd = d.Alias("x", "rdfentry_").Define("y", "x*x")
graph = dd.Graph("x", "y")
# This tutorial is ran with multithreading enabled. The order in which points are inserted is not known, so to have a meaningful representation points are sorted.