This Python function is useful for argparse declarations that receive directories that both need to be verified existing and converted to absolute paths.

absolutepath.py

'''
Copyright 2017 Doug McGeehan under the GPLv3.
'''

import os


def verified_absolute_path(path):
    abs_path = os.path.abspath(path)
    assert os.path.isdir(abs_path),\
           'No directory exists at "{}"'.format(abs_path)
    return abs_path


# Demonstrate the script
if __name__ == '__main__':
    current_dir = '.'
    abs_path = verified_absolute_path(current_dir)
    print('Converted {0} to {1}'.format(current_dir, abs_path))