1. from ROOT import TGraph
    2. from ROOT import kRed
    3. from array import array
    5. gr1 = TGraph('data.txt') # xs,ys
    6. gr1.SetLineColor(kRed)
    7. gr1.Draw()
    9. xs = array('d',[0,1,2,3])
    10. ys = array('d',[0,1,2,3])
    11. gr2 = TGraph(len(xs),xs,ys)
    12. gr.Draw()