Creating a Script

#! /usr/bin/env python
# Usage: ./todd.py filenametoconvert.ngc
# Output: converted_filenametoconvert.ngc

import sys

def main(argv):

  openfile = open(argv[0], 'r')
  file_in = openfile.readlines()
  openfile.close()

  file_out = []
  for line in file_in:
    # print line
    if line.find('Z') != -1:
      words = line.rstrip('\n')
      words = words.split(' ')
      newword = ''
      for i in words:
        if i[0] == 'Z':
          newword = 'W'+ i[1:]
      if len(newword) > 0:
        words.append(newword)
        newline = ' '.join(words)
        file_out.append(newline)
    else:
      file_out.append(line)
  newfile = open('converted_'+argv[0], 'w')
  for item in file_out:
    newfile.write("%s\n" % item)
  newfile.close()

if __name__ == "__main__":
   main(sys.argv[1:])

cd convert_directory
./todd.py filename.ngc