Last login: Tue May 15 13:33:50 on ttys000
Louis-MacBook-Pro:~ louisling$ root
   ------------------------------------------------------------------
  | Welcome to ROOT 6.15/01                      http://root.cern.ch |
  |                                     (c) 1995-2018, The ROOT Team |
  | Built for macosx64                                               |
  | From heads/master@v6-13-04-34-g5298b418ee, May 09 2018, 20:04:12 |
  | Try '.help', '.demo', '.license', '.credits', '.quit'/'.q'       |
   ------------------------------------------------------------------

root [0] .q
Louis-MacBook-Pro:~ louisling$ python /Users/louisling/Desktop/demo1.py 
Louis-MacBook-Pro:~ louisling$ sudo python /Users/louisling/Desktop/demo1.py 
Password:
Traceback (most recent call last):
  File "/Users/louisling/Desktop/demo1.py", line 1, in <module>
    from ROOT import gROOT, TCanvas, TF1
ImportError: No module named ROOT
Louis-MacBook-Pro:~ louisling$