从字节大小返回人类可读大小的函数:
>>> human_readable(2048)
'2 kilobytes'
>>>
如何做到这一点?
从字节大小返回人类可读大小的函数:
>>> human_readable(2048)
'2 kilobytes'
>>>
如何做到这一点?
当前回答
我喜欢senderle的十进制版本的固定精度,所以这里有一种与上面joctee的答案的混合(你知道你可以取非整数底数的对数吗?):
from math import log
def human_readable_bytes(x):
# hybrid of https://stackoverflow.com/a/10171475/2595465
# with https://stackoverflow.com/a/5414105/2595465
if x == 0: return '0'
magnitude = int(log(abs(x),10.24))
if magnitude > 16:
format_str = '%iP'
denominator_mag = 15
else:
float_fmt = '%2.1f' if magnitude % 3 == 1 else '%1.2f'
illion = (magnitude + 1) // 3
format_str = float_fmt + ['', 'K', 'M', 'G', 'T', 'P'][illion]
return (format_str % (x * 1.0 / (1024 ** illion))).lstrip('0')
其他回答
这是我为另一个问题写的东西……
与xApple的答案非常相似,该对象总是以人类可读的格式打印。不同的是,它也是一个适当的int,所以你可以用它做数学! 它将格式说明符直接传递给数字格式,并附加后缀,因此几乎可以保证请求的长度将超出两到三个字符。我从来没有使用过这个代码,所以我没有费心去修复它!
class ByteSize(int):
_KB = 1024
_suffixes = 'B', 'KB', 'MB', 'GB', 'PB'
def __new__(cls, *args, **kwargs):
return super().__new__(cls, *args, **kwargs)
def __init__(self, *args, **kwargs):
self.bytes = self.B = int(self)
self.kilobytes = self.KB = self / self._KB**1
self.megabytes = self.MB = self / self._KB**2
self.gigabytes = self.GB = self / self._KB**3
self.petabytes = self.PB = self / self._KB**4
*suffixes, last = self._suffixes
suffix = next((
suffix
for suffix in suffixes
if 1 < getattr(self, suffix) < self._KB
), last)
self.readable = suffix, getattr(self, suffix)
super().__init__()
def __str__(self):
return self.__format__('.2f')
def __repr__(self):
return '{}({})'.format(self.__class__.__name__, super().__repr__())
def __format__(self, format_spec):
suffix, val = self.readable
return '{val:{fmt}} {suf}'.format(val=val, fmt=format_spec, suf=suffix)
def __sub__(self, other):
return self.__class__(super().__sub__(other))
def __add__(self, other):
return self.__class__(super().__add__(other))
def __mul__(self, other):
return self.__class__(super().__mul__(other))
def __rsub__(self, other):
return self.__class__(super().__sub__(other))
def __radd__(self, other):
return self.__class__(super().__add__(other))
def __rmul__(self, other):
return self.__class__(super().__rmul__(other))
用法:
>>> size = 6239397620
>>> print(size)
5.81 GB
>>> size.GB
5.810891855508089
>>> size.gigabytes
5.810891855508089
>>> size.PB
0.005674699077644618
>>> size.MB
5950.353260040283
>>> size
ByteSize(6239397620)
如果有人想知道,要将@Sridhar Ratnakumar的答案转换回字节,您可以执行以下操作:
import math
def format_back_to_bytes(value):
for power, unit in enumerate(["", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi"]):
if value[-3:-1] == unit:
return round(float(value[:-3])*math.pow(2, 10*power))
用法:
>>> format_back_to_bytes('212.4GiB')
228062763418
您将在下面发现的决不是已经发布的解决方案中性能最好或最短的解决方案。相反,它专注于一个许多其他答案都忽略的特定问题。
即输入如999_995时的情况:
Python 3.6.1 ...
...
>>> value = 999_995
>>> base = 1000
>>> math.log(value, base)
1.999999276174054
哪个,被截断为最近的整数,并应用回输入给出
>>> order = int(math.log(value, base))
>>> value/base**order
999.995
这似乎正是我们所期望的,直到我们被要求控制输出精度。这就是事情开始变得有点困难的时候。
将精度设置为2位,我们得到:
>>> round(value/base**order, 2)
1000 # K
而不是1M。
我们该如何应对呢?
当然,我们可以显式地检查它:
if round(value/base**order, 2) == base:
order += 1
但我们能做得更好吗?在我们做最后一步之前,我们能知道订单应该怎么削减吗?
事实证明我们可以。
假设0.5十进制舍入规则,则上述if条件转化为:
导致
def abbreviate(value, base=1000, precision=2, suffixes=None):
if suffixes is None:
suffixes = ['', 'K', 'M', 'B', 'T']
if value == 0:
return f'{0}{suffixes[0]}'
order_max = len(suffixes) - 1
order = log(abs(value), base)
order_corr = order - int(order) >= log(base - 0.5/10**precision, base)
order = min(int(order) + order_corr, order_max)
factored = round(value/base**order, precision)
return f'{factored:,g}{suffixes[order]}'
给
>>> abbreviate(999_994)
'999.99K'
>>> abbreviate(999_995)
'1M'
>>> abbreviate(999_995, precision=3)
'999.995K'
>>> abbreviate(2042, base=1024)
'1.99K'
>>> abbreviate(2043, base=1024)
'2K'
根据之前所有的答案,以下是我的看法。它是一个以字节为单位以整数形式存储文件大小的对象。但是当你尝试打印对象时,你会自动得到一个人类可读的版本。
class Filesize(object):
"""
Container for a size in bytes with a human readable representation
Use it like this::
>>> size = Filesize(123123123)
>>> print size
'117.4 MB'
"""
chunk = 1024
units = ['bytes', 'KB', 'MB', 'GB', 'TB', 'PB']
precisions = [0, 0, 1, 2, 2, 2]
def __init__(self, size):
self.size = size
def __int__(self):
return self.size
def __str__(self):
if self.size == 0: return '0 bytes'
from math import log
unit = self.units[min(int(log(self.size, self.chunk)), len(self.units) - 1)]
return self.format(unit)
def format(self, unit):
if unit not in self.units: raise Exception("Not a valid file size unit: %s" % unit)
if self.size == 1 and unit == 'bytes': return '1 byte'
exponent = self.units.index(unit)
quotient = float(self.size) / self.chunk**exponent
precision = self.precisions[exponent]
format_string = '{:.%sf} {}' % (precision)
return format_string.format(quotient, unit)
总有一个这样的人。今天轮到我了。这是一行代码——如果算上函数签名的话是两行。
def human_size(bytes, units=[' bytes','KB','MB','GB','TB', 'PB', 'EB']):
""" Returns a human readable string representation of bytes """
return str(bytes) + units[0] if bytes < 1024 else human_size(bytes>>10, units[1:])
>>> human_size(123)
123 bytes
>>> human_size(123456789)
117GB
如果你需要大于1艾字节的大小,那就有点麻烦了:
def human_size(bytes, units=[' bytes','KB','MB','GB','TB', 'PB', 'EB']):
return str(bytes) + units[0] if bytes < 1024 else human_size(bytes>>10, units[1:]) if units[1:] else f'{bytes>>10}ZB'