python/human-readable.py

   1 #!/usr/bin/env python
   2
   3 """
   4 Bytes-to-human / human-to-bytes converter.
   5 Based on: http://goo.gl/kTQMs
   6 Working with Python 2.x and 3.x.
   7
   8 Author: Giampaolo Rodola' <g.rodola [AT] gmail [DOT] com>
   9 License: MIT
  10
  11 http://code.activestate.com/recipes/578019-bytes-to-human-human-to-bytes-converter/
  12 """
  13
  14 # see: http://goo.gl/kTQMs
  15 SYMBOLS = {
  16     'customary'     : ('B', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'),
  17     'customary_ext' : ('byte', 'kilo', 'mega', 'giga', 'tera', 'peta', 'exa',
  18                        'zetta', 'iotta'),
  19     'iec'           : ('Bi', 'Ki', 'Mi', 'Gi', 'Ti', 'Pi', 'Ei', 'Zi', 'Yi'),
  20     'iec_ext'       : ('byte', 'kibi', 'mebi', 'gibi', 'tebi', 'pebi', 'exbi',
  21                        'zebi', 'yobi'),
  22 }
  23
  24 def bytes2human(n, format='%(value).1f %(symbol)s', symbols='customary'):
  25     """
  26     Convert n bytes into a human readable string based on format.
  27     symbols can be either "customary", "customary_ext", "iec" or "iec_ext",
  28     see: http://goo.gl/kTQMs
  29
  30       >>> bytes2human(0)
  31       '0.0 B'
  32       >>> bytes2human(0.9)
  33       '0.0 B'
  34       >>> bytes2human(1)
  35       '1.0 B'
  36       >>> bytes2human(1.9)
  37       '1.0 B'
  38       >>> bytes2human(1024)
  39       '1.0 K'
  40       >>> bytes2human(1048576)
  41       '1.0 M'
  42       >>> bytes2human(1099511627776127398123789121)
  43       '909.5 Y'
  44
  45       >>> bytes2human(9856, symbols="customary")
  46       '9.6 K'
  47       >>> bytes2human(9856, symbols="customary_ext")
  48       '9.6 kilo'
  49       >>> bytes2human(9856, symbols="iec")
  50       '9.6 Ki'
  51       >>> bytes2human(9856, symbols="iec_ext")
  52       '9.6 kibi'
  53
  54       >>> bytes2human(10000, "%(value).1f %(symbol)s/sec")
  55       '9.8 K/sec'
  56
  57       >>> # precision can be adjusted by playing with %f operator
  58       >>> bytes2human(10000, format="%(value).5f %(symbol)s")
  59       '9.76562 K'
  60     """
  61     n = int(n)
  62     if n < 0:
  63         raise ValueError("n < 0")
  64     symbols = SYMBOLS[symbols]
  65     prefix = {}
  66     for i, s in enumerate(symbols[1:]):
  67         prefix[s] = 1 << (i+1)*10
  68     for symbol in reversed(symbols[1:]):
  69         if n >= prefix[symbol]:
  70             value = float(n) / prefix[symbol]
  71             return format % locals()
  72     return format % dict(symbol=symbols[0], value=n)
  73
  74 def human2bytes(s):
  75     """
  76     Attempts to guess the string format based on default symbols
  77     set and return the corresponding bytes as an integer.
  78     When unable to recognize the format ValueError is raised.
  79
  80       >>> human2bytes('0 B')
  81       0
  82       >>> human2bytes('1 K')
  83       1024
  84       >>> human2bytes('1 M')
  85       1048576
  86       >>> human2bytes('1 Gi')
  87       1073741824
  88       >>> human2bytes('1 tera')
  89       1099511627776
  90
  91       >>> human2bytes('0.5kilo')
  92       512
  93       >>> human2bytes('0.1  byte')
  94       0
  95       >>> human2bytes('1 k')  # k is an alias for K
  96       1024
  97       >>> human2bytes('12 foo')
  98       Traceback (most recent call last):
  99           ...
 100       ValueError: can't interpret '12 foo'
 101     """
 102     init = s
 103     num = ""
 104     while s and s[0:1].isdigit() or s[0:1] == '.':
 105         num += s[0]
 106         s = s[1:]
 107     num = float(num)
 108     letter = s.strip()
 109     for name, sset in SYMBOLS.items():
 110         if letter in sset:
 111             break
 112     else:
 113         if letter == 'k':
 114             # treat 'k' as an alias for 'K' as per: http://goo.gl/kTQMs
 115             sset = SYMBOLS['customary']
 116             letter = letter.upper()
 117         else:
 118             raise ValueError("can't interpret %r" % init)
 119     prefix = {sset[0]:1}
 120     for i, s in enumerate(sset[1:]):
 121         prefix[s] = 1 << (i+1)*10
 122     return int(num * prefix[letter])
 123
 124
 125 if __name__ == "__main__":
 126     #import doctest
 127     #doctest.testmod()
 128     import sys
 129     print(bytes2human(sys.argv[1]))
 130     print(human2bytes(sys.argv[2]))
 131