如何扩展此python脚本以通过命令行而不是提示来接受用户输入？

Question

Currently, I have a python script which takes in a text file, checks for passages enclosed by a tag ##Somethinghere## and asks the user how many times does he/she want to copy it. So for instance if I have the text file:

Random Text File

##RandomLine1##
Random Line 1
##RandomLine1##

Random Line 2

##RandomLine3##
Random Line 2
##RandomLine3##

End of file

The user is prompted:

Loop "RandomLine1" how many times?
Loop "RandomLine3" how many times?

Once the user enters the numbers, the specific enclosed lines are copied the indicated number of times, and the tags are removed. The text after being copied however many times is output to a designated output file.

To start the script, the command looks like this:

python script.py inputfile outputfile

What I want to do is instead of prompting the user for input, the user can optionally input the number of loops as optional command line parameters. Something like:

python script.py inputfile outputfile --RandomLine1 2 --RandomLine3 2

Is this possible for a python script? I am attaching the current version of the script below:

import re
import argparse

pattern = '##([^#]*)##'

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('infile', type=argparse.FileType('r'))
    parser.add_argument('outfile', type=argparse.FileType('w'))
    args = parser.parse_args()

    matcher = re.compile(pattern)
    tagChecker = False
    strList = []
    for line in args.infile:
        if tagChecker is True:
            lineTest = matcher.search(line)
            if lineTest:
                tagChecker = False
                for _ in range(int(raw_input('Loop ' + lineTest.string[2:-3] + ' how many times?')) - 1):
                    for copyLine in strList:
                        args.outfile.write(copyLine)
                new_line = matcher.sub("", line)
                args.outfile.write(new_line)
                strList = []
                continue
            else:
                strList.append(line)
                args.outfile.write(line)
        if tagChecker is False:
            lineTest = matcher.search(line)
            if lineTest:
                tagChecker = True
                new_line = matcher.sub("", line)
                args.outfile.write(new_line)
            else:
                args.outfile.write(line)

    args.infile.close()
    args.outfile.close()

if __name__ == '__main__':
    main()

Answer 1

Yes you can do this by adding default values to your arguments:

parser.add_argument("--RandomLine1", default=None)
# same for RandomLine2

# ...

if args.RandomLine1 is not None:
    # use args.RandomLine1 as a number
    #...
else:
    # RandomNumber1 is not given in the args
    #...

Answer 2

How about using sys.argv ?

sys.argv returns a list of the arguments your script is passed separated by space, with sys.argv[0] being the name of the script.

So for the following program:

import sys
print sys.argv

when run in the following way:

python script.py inputfile outputfile --RandomLine1 2 --RandomLine3 2

will produce the following output:

['script.py', 'inputfile', 'outputfile', '--RandomLine1', '2', '--Randomline3', '2']

If you would like to create a dictionary of the lines and the corresponding arguments try something along the lines of the following:

# Get portion of list that isn't the script name or input/output file name
args = sys.argv[3:]
args_dict = {}

i = 0
while i < len(args):
    if args[i].startswith('--'):
        line = args[i].replace('--', '')
        try:
             args_dict[line] = int(arg[i+1])
        except IndexError:
             print "%s has no argument" % line
        i += 1

For your input example we would get args_dict == {'RandomLine1': 2, 'RandomLine3': 2} . I think it's pretty easy to see how to use the dictionary for whatever purpose you wish from there.

The above code could of course be done more/less thoroughly depending on how reliable you expect the input to be.