Python argument parser list of list or tuple of tuples
Question: I'm trying to use argument parser to parse a 3D coordinate so I can use

    
    
    --cord 1,2,3 2,4,6 3,6,9
    

and get

    
    
    ((1,2,3),(2,4,6),(3,6,9))
    

My attempt is

    
    
    import argparse
    parser = argparse.ArgumentParser()
    parser.add_argument('--cord', help="Coordinate", dest="cord", type=tuple, nargs=3)
    args = parser.parse_args(["--cord","1,2,3","2,4,6","3,6,9"])
    
    vars(args) 
    {'cord': [('1', ',', '2', ',', '3'),
      ('2', ',', '4', ',', '6'),
      ('3', ',', '6', ',', '9')]}
    

What would the replacement of the comma be?


Answer: You can add your own
[type](http://docs.python.org/library/argparse.html#type). This also allows
for additional validations, for example:

    
    
    def coords(s):
        try:
            x, y, z = map(int, s.split(','))
            return x, y, z
        except:
            raise argparse.ArgumentTypeError("Coordinates must be x,y,z")
    
    
    parser.add_argument('--cord', help="Coordinate", dest="cord", type=coords, nargs=3)
    

