```--reverse-column-indices``` triggers an erro

[Lordmzn]

Thank you for the enhancement! It exactly fits what I need to do. Sadly I'm not being able to make it work: below the command and the result. (I'm using python 2.7.1 on macOSX 10.7.5)

emanuele$ python pareto.py -o 0-1 -e 5.0 5000.0 --output HB_200K.reference --comment "#" --contribution --line-number --reverse-column-indices ANN* RBF* 
Traceback (most recent call last):
  File "pareto.py", line 485, in <module>
    cli(get_args(sys.argv))
  File "pareto.py", line 112, in get_args
    args.maximize = [-1 -ob for ob in args.maximize]
TypeError: 'NoneType' object is not iterable

even if I specify just one column, it says

emanuele$ python pareto.py -o 0 -e 5.0 5000.0 --output HB_200K.reference --comment "#" --contribution --line-number --reverse-column-indices ANN* RBF* 
Traceback (most recent call last):
  File "pareto.py", line 485, in <module>
    cli(get_args(sys.argv))
  File "pareto.py", line 112, in get_args
    args.maximize = [-1 -ob for ob in args.maximize]
TypeError: 'NoneType' object is not iterable

I'm glad to give you any help I can

[jdherman]

I'm guessing this just needs a:
if args.maximize is not None:
in front of it.

Try it now. Sorry about that.

[matthewjwoodruff]

Oops! Should have tested that without a maximization objective! Thanks for the fix Jon, that's exactly the problem.

[jdherman]

Cool. I also put in the check for objectives, because if I remember right objectives aren't a required argument ... the default behavior is to sort all columns, right?

[matthewjwoodruff]

Yes, that's quite right, and a good catch as well. I just made an issue for better testing --- this is a corner case we easily could have let slip.

[matthewjwoodruff]

Emanuele, let us know if you have any more trouble. Thanks!

[Lordmzn]

Now it works like perfectly on my case study, thank you!

[matthewjwoodruff]

Thanks for the feedback, and for helping to make pareto.py better!