sys.argv is itself a list. You can directly access the `quality` field as sys.argv[2].
quality = int(sys.argv[2]) However, if you want to use more command line options, then using `argparse` module is better than accessing arguments using `sys.argv`. Import `argparse` module and create a parser import argparse parser = argparse.ArgumentParser(description='My example command line option parser') #Add as many arguments as you want to parse (from the command line) parser.add_argument('--quality', type=int, help='Quality score') parser.add_argument("--some-other-option", help="Some other option for example") ... ... #Parse the arguments (to be)given on the command line(when the script is invoked) args = parser.parse_args() #Access all the arguments or options as `args.quality`, `args.some_other_option`, etc. print("quality =", args.quality) print("some-other-option =", args.some_other_option) Read the documentation of argparse for better understanding. https://docs.python.org/2/library/argparse.html On 10 April 2014 00:53, rohan bareja <rohan_1...@yahoo.co.in> wrote: > I want to write a function in Python for a tab delimited file I am dealing > with,to filter out values from a column, and put that parameter as a command > line option while running the script. > > So,if the limit is 10,the filter out all the rows with values less than 10. > Also,I want to check if the number entered is numeric or not else display > the message "its not numeric". > > > So,the command line would be: > > python script.py file --quality [limit] > > > The Python script: > > import sys > arg = [] > for a in sys.argv: > arg.append(a) > quality = arg[2] > > > To be more specific,the file I am dealing with is a Samfile,and using > package > Pysam,which has mapping quality limits in the 5th column. > > https://media.readthedocs.org/pdf/pysam/latest/pysam.pdf > > Commandline: > > python script.py samfile --quality [limit] > > I am reading the samfile using this: > > samfile = pysam.Samfile(arg[1], "rb" ) > mapqlim = arg[2] > > I am a Python beginner,but saw one of the modules,argparse. How can I > accomplish this using argparse in Python? > > > > -- > https://mail.python.org/mailman/listinfo/python-list > -- :-)balaji -- https://mail.python.org/mailman/listinfo/python-list