du.py

__main__.py

import sys
from du import main

if __name__=='__main__':
    if len(sys.argv) > 1:
        main.main(sys.argv[1])
    else:
        main.main()

main.py

import os
import os.path
import sys

def humanize(num):
    """
    >>> humanize(500)
    '500'
    >>> humanize(1000)
    '1.0k'
    >>> humanize(21000)
    '21k'
    >>> humanize(321000)
    '321k'
    >>> humanize(4321000)
    '4.3m'
    >>> humanize(54321000)
    '54m'
    >>> humanize(654321000)
    '654m'
    >>> humanize(7654321000)
    '7.6g'
    """
    if num < 1000:
        return str(num)
    order = " kmgt"[(len(str(num)) - 1) // 3]
    head = str(num)[0:len(str(num)) - ((len(str(num)) - 1) // 3) * 3]
    if len(head) == 1:
        head += "." + str(num)[1]
    return head + order

def total_size(path):
    total = 0
    if os.path.isdir(path):
      for dirpath, dirnames, filenames in os.walk(path):
          for f in filenames + dirnames:
              try:
                  total += os.stat(os.path.join(dirpath, f)).st_size
              except FileNotFoundError:
                  pass
    else:
        total = os.stat(path).st_size
    return total

def main(start=None):
    if start:
        dirs = [start]
    else:
        dirs = os.listdir(start)

    for path in dirs:
        print("{0:>4} {1}".format(humanize(total_size(path)), path))

if __name__=='__main__':
    if len(sys.argv) > 1:
        main(sys.argv[1])
    else:
        main()