TSP SYS

Answered

Jose Vindel

March 24, 2020 21:29

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Hello, I am trying to understand the code on the TSP where cuts are added to eliminate subtours, but I still don't quite get the purpose of sys, I don't get 

 

len(sys.arg) > 2

does sys.arg returns a list?

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  June 23, 2025 03:16 Edited

  This post is more than three years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum. Or why not try our AI Gurobot?.
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  Jose Vindel

  March 24, 2020 21:50

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  After reading some documentation on sys, I now know it gives back a list, in the case for the TSP problem what's the list of?

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  Eli Towle

  • Gurobi Staff

  March 24, 2020 22:56

  Hi Jose,

  sys.argv is a list of the command-line arguments used when running the program. The first argument is always the name of the program.

  The tsp.py example is meant to be run from the command line with the syntax

  python tsp.py N

  where N is an integer representing the number of random cities to use when solving the TSP. The second argument is used to construct a list of random points:

  n = int(sys.argv[1])
  random.seed(1)
  points = [(random.randint(0, 100), random.randint(0, 100)) for i in range(n)]

  If you want to fix the number of cities within the code rather than specifying it via command-line argument, you can replace the lines

  if len(sys.argv) < 2:
      print('Usage: tsp.py npoints')
      sys.exit(1)
  n = int(sys.argv[1])

  with (e.g.):

  n = 25

  Thanks!

  Eli

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  Jose Vindel

  March 24, 2020 23:10

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  Thank you so much for your answer, it clarifies a lot. No wonder when I tried to run it from Jupyter Notebook it showed an error message

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