example of how i like to pass arguments to python programs

starting_right.py

# these are the libraries needed
import sys, getopt
from Tkinter import Tk
from tkFileDialog import askopenfilename
import numpy as np

# get list of input arguments and pre-allocate arrays
argv = sys.argv[1:]
inputfile = ''; arg2 = ''
arg3 = ''; arg4 = ''

# parse inputs to variables
try:
   opts, args = getopt.getopt(argv,"ha:b:c:d:")
except getopt.GetoptError:
     print 'my_script.py -a <inputfile> -b <arg2> -c <arg3> -d <arg4>'
     sys.exit(2)
for opt, arg in opts:
   if opt == '-h': # h is 'help'
      print 'my_script.py -a <inputfile> -b <arg2> -c <arg3> -d <arg4>'
      sys.exit()
   elif opt in ("-a"):
      inputfile = arg
   elif opt in ("-b"):
      arg2 = arg
   elif opt in ("-c"):
      arg3 = arg
   elif opt in ("-d"):
      arg4 = arg

# prompt user to supply file if no input file given
if not inputfile:
   print 'An input file is required!!!!!!'
   # we don't want a full GUI, so keep the root window from appearing
   Tk().withdraw() 
   # show an "Open" dialog box and return the path to the selected file
   inputfile = askopenfilename(filetypes=[("JPG files","*.jpg")]) 
   

# print given arguments to screen and convert data type where necessary
# let's assume arg2 is meant to be an integer, arg3 is a float, and arg4 is a string

# let's further assume arg2 and arg3 are meant to be numpy arrays

if inputfile:
   print 'Input file is %s' % (inputfile)
if arg2:
   arg2 = np.asarray(arg2,int)
   print 'Argument 2 is %s' % (str(arg2))
if arg3:
   arg3 = np.asarray(arg3,float)
   print 'Argument 3 is %s' % (str(arg2))
if arg4:
   print 'Argument 4 is %s' % (arg4)

# if arguments not supplied, use defaults
if not arg2:
   arg2 = 100
   print '[Default] Argument 2 is %s' % (str(arg2))

if not arg3:
   arg3 = 0.1
   print '[Default] Argument 3 is %s' % (str(arg3))

if not arg4:
   arg4 = 'hello'
   print '[Default] Argument 4 is %s' % (arg4)