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## {{{ http://code.activestate.com/recipes/578019/ (r4)
## {{{ http://code.activestate.com/recipes/578019/ (r2)
#!/usr/bin/env python

"""
Bytes to human and human to bytes converter.
"""

# Author: Giampaolo Rodola' <g.rodola [AT] gmail [DOT] com>
# License: MIT

# see: http://goo.gl/kTQMs
_customary = ('B', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y')
_customary_ext = ('byte', 'kilo', 'mega', 'giga', 'tera',
                  'peta', 'exa', 'zetta', 'iotta')
_iec = ('Bi', 'Ki', 'Mi', 'Gi', 'Ti', 'Pi', 'Ei', 'Zi', 'Yi')
_iec_ext = ('byte', 'kibi', 'mebi', 'gibi', 'tebi', 'pebi',
            'exbi', 'zebi', 'yobi')
_symbols_set = (_customary, _customary_ext, _iec, _iec_ext)
_symbols_map = dict(customary=_customary, customary_ext=_customary_ext,
                    iec=_iec, iec_ext=_iec_ext)

def bytes2human(n, format="%(value).1f %(symbol)s", symbols="customary"):
    """
    Convert n bytes into a human readable string based on format.
    symbols can be either "customary", "customary_ext", "iec" or "iec_ext",
    see: http://goo.gl/kTQMs

    Doctests:

    >>> bytes2human(0)
    '0.0 B'
    >>> bytes2human(0.9)
    '0.0 B'
    >>> bytes2human(1)
    '1.0 B'
    >>> bytes2human(1.9)
    '1.0 B'
    >>> bytes2human(1024)
    '1.0 K'
    >>> bytes2human(1048576)
    '1.0 M'
    >>> bytes2human(1099511627776127398123789121)
    '909.5 Y'

    >>> bytes2human(9856, symbols="customary")
    '9.6 K'
    >>> bytes2human(9856, symbols="customary_ext")
    '9.6 kilo'
    >>> bytes2human(9856, symbols="iec")
    '9.6 Ki'
    >>> bytes2human(9856, symbols="iec_ext")
    '9.6 kibi'

    >>> bytes2human(10000, "%(value).1f %(symbol)s/sec")
    '9.8 K/sec'

    >>> # precision can be adjusted by playing with %f operator
    >>> bytes2human(10000, format="%(value).5f %(symbol)s")
    '9.76562 K'
    """
    n = int(n)
    if n < 0:
        raise ValueError("n < 0")
    symbols = _symbols_map[symbols]
    prefix = {}
    for i, s in enumerate(symbols[1:]):
        prefix[s] = 1 << (i+1)*10
    for symbol in reversed(symbols[1:]):
        if n >= prefix[symbol]:
            value = float(n) / prefix[symbol]
            return format % locals()
    return format % dict(symbol=symbols[0], value=n)

def human2bytes(s):
    """
    Attempts to guess the string format based on default symbols
    set and return the corresponding bytes as an integer.
    If unable to recognize the format ValueError is raised.

    Doctests:

    >>> human2bytes('0 B')
    0
    >>> human2bytes('1 K')
    1024
    >>> human2bytes('1 M')
    1048576
    >>> human2bytes('1 Gi')
    1073741824
    >>> human2bytes('1 tera')
    1099511627776

    >>> human2bytes('0.5kilo')
    512
    >>> human2bytes('0.1  byte')
    0
    >>> human2bytes('1 k')  # k is an alias for K
    1024
    """
    init = s
    num = ""
    while s and s[0:1].isdigit() or s[0:1] == '.':
        num += s[0]
        s = s[1:]
    num = float(num)
    letter = s.strip()
    for sset in _symbols_set:
        if letter in sset:
            break
    else:
        if letter == 'k':
            # treat 'k' as an alias for 'K' as per: http://goo.gl/kTQMs
            sset = _customary
            letter = letter.upper()
        else:
            raise ValueError("can't interpret %r" % init)
    prefix = {sset[0]:1}
    for i, s in enumerate(sset[1:]):
        prefix[s] = 1 << (i+1)*10
    return int(num * prefix[letter])


if __name__ == "__main__":
    import doctest
    doctest.testmod()
## end of http://code.activestate.com/recipes/578019/ }}}
## end of http://code.activestate.com/recipes/578019/ }}}

Diff to Previous Revision

--- revision 4 2012-01-19 00:02:16
+++ revision 5 2012-01-19 00:03:45
@@ -1,3 +1,4 @@
+## {{{ http://code.activestate.com/recipes/578019/ (r4)
 ## {{{ http://code.activestate.com/recipes/578019/ (r2)
 #!/usr/bin/env python
 
@@ -96,14 +97,6 @@
     0
     >>> human2bytes('1 k')  # k is an alias for K
     1024
-
-    >>> human2bytes('1.5 foo')
-    Traceback (most recent call last):
-      File "<stdin>", line 1, in <module>
-      File "foo2.py", line 67, in human2bytes
-        prefix[s] = 1 << (i+1)*10
-    ValueError: can't interpret '1.5 foo'
-    >>>
     """
     init = s
     num = ""
@@ -132,3 +125,4 @@
     import doctest
     doctest.testmod()
 ## end of http://code.activestate.com/recipes/578019/ }}}
+## end of http://code.activestate.com/recipes/578019/ }}}

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