I am using a library that reads a file and returns its size in bytes.
This file size is then displayed to the end user; to make it easier for them to understand it, I am explicitly converting the file size to MB by dividing it by 1024.0 * 1024.0. Of course this works, but I am wondering is there a better way to do this in Python?
By better, I mean perhaps a stdlib function that can manipulate sizes according to the type I want. Like if I specify MB, it automatically divides it by 1024.0 * 1024.0. Somethign on these lines.
I wanted 2 way conversion, and I wanted to use Python 3 format() support to be most pythonic. Maybe try datasize library module? https://pypi.org/project/datasize/
$ pip install -qqq datasize
$ python
...
>>> from datasize import DataSize
>>> 'My new {:GB} SSD really only stores {:.2GiB} of data.'.format(DataSize('750GB'),DataSize(DataSize('750GB') * 0.8))
'My new 750GB SSD really only stores 558.79GiB of data.'
Instead of a size divisor of 1024 * 1024 you could use the << bitwise shifting operator, i.e. 1<<20 to get megabytes, 1<<30 to get gigabytes, etc.
In the simplest scenario you can have e.g. a constant MBFACTOR = float(1<<20) which can then be used with bytes, i.e.: megas = size_in_bytes/MBFACTOR.
Megabytes are usually all that you need, or otherwise something like this can be used:
# bytes pretty-printing
UNITS_MAPPING = [
(1<<50, ' PB'),
(1<<40, ' TB'),
(1<<30, ' GB'),
(1<<20, ' MB'),
(1<<10, ' KB'),
(1, (' byte', ' bytes')),
]
def pretty_size(bytes, units=UNITS_MAPPING):
"""Get human-readable file sizes.
simplified version of https://pypi.python.org/pypi/hurry.filesize/
"""
for factor, suffix in units:
if bytes >= factor:
break
amount = int(bytes / factor)
if isinstance(suffix, tuple):
singular, multiple = suffix
if amount == 1:
suffix = singular
else:
suffix = multiple
return str(amount) + suffix
print(pretty_size(1))
print(pretty_size(42))
print(pretty_size(4096))
print(pretty_size(238048577))
print(pretty_size(334073741824))
print(pretty_size(96995116277763))
print(pretty_size(3125899904842624))
## [Out] ###########################
1 byte
42 bytes
4 KB
227 MB
311 GB
88 TB
2 PB
Here is my implementation:
from bisect import bisect
def to_filesize(bytes_num, si=True):
decade = 1000 if si else 1024
partitions = tuple(decade ** n for n in range(1, 6))
suffixes = tuple('BKMGTP')
i = bisect(partitions, bytes_num)
s = suffixes[i]
for n in range(i):
bytes_num /= decade
f = '{:.3f}'.format(bytes_num)
return '{}{}'.format(f.rstrip('0').rstrip('.'), s)
It will print up to three decimals and it strips trailing zeros and periods. The boolean parameter si will toggle usage of 10-based vs. 2-based size magnitude.
This is its counterpart. It allows to write clean configuration files like {'maximum_filesize': from_filesize('10M'). It returns an integer that approximates the intended filesize. I am not using bit shifting because the source value is a floating point number (it will accept from_filesize('2.15M') just fine). Converting it to an integer/decimal would work but makes the code more complicated and it already works as it is.
def from_filesize(spec, si=True):
decade = 1000 if si else 1024
suffixes = tuple('BKMGTP')
num = float(spec[:-1])
s = spec[-1]
i = suffixes.index(s)
for n in range(i):
num *= decade
return int(num)
Here's a version that matches the output of ls -lh.
def human_size(num: int) -> str:
base = 1
for unit in ['B', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y']:
n = num / base
if n < 9.95 and unit != 'B':
# Less than 10 then keep 1 decimal place
value = "{:.1f}{}".format(n, unit)
return value
if round(n) < 1000:
# Less than 4 digits so use this
value = "{}{}".format(round(n), unit)
return value
base *= 1024
value = "{}{}".format(round(n), unit)
return value
Here are some easy-to-copy one liners to use if you already know what unit size you want. If you're looking for in a more generic function with a few nice options, see my FEB 2021 update further on...
print ('{:,.0f}'.format(os.path.getsize(filepath))+" B")
print ('{:,.0f}'.format(os.path.getsize(filepath)/float(1<<7))+" kb")
print ('{:,.0f}'.format(os.path.getsize(filepath)/float(1<<10))+" KB")
print ('{:,.0f}'.format(os.path.getsize(filepath)/float(1<<17))+" mb")
print ('{:,.0f}'.format(os.path.getsize(filepath)/float(1<<20))+" MB")
print ('{:,.0f}'.format(os.path.getsize(filepath)/float(1<<27))+" gb")
print ('{:,.0f}'.format(os.path.getsize(filepath)/float(1<<30))+" GB")
print ('{:,.0f}'.format(os.path.getsize(filepath)/float(1<<40))+" TB")
UPDATE FEB 2021 Here are my updated and fleshed-out functions to a) get file/folder size, b) convert into desired units:
from pathlib import Path
def get_path_size(path = Path('.'), recursive=False):
"""
Gets file size, or total directory size
Parameters
----------
path: str | pathlib.Path
File path or directory/folder path
recursive: bool
True -> use .rglob i.e. include nested files and directories
False -> use .glob i.e. only process current directory/folder
Returns
-------
int:
File size or recursive directory size in bytes
Use cleverutils.format_bytes to convert to other units e.g. MB
"""
path = Path(path)
if path.is_file():
size = path.stat().st_size
elif path.is_dir():
path_glob = path.rglob('*.*') if recursive else path.glob('*.*')
size = sum(file.stat().st_size for file in path_glob)
return size
def format_bytes(bytes, unit, SI=False):
"""
Converts bytes to common units such as kb, kib, KB, mb, mib, MB
Parameters
---------
bytes: int
Number of bytes to be converted
unit: str
Desired unit of measure for output
SI: bool
True -> Use SI standard e.g. KB = 1000 bytes
False -> Use JEDEC standard e.g. KB = 1024 bytes
Returns
-------
str:
E.g. "7 MiB" where MiB is the original unit abbreviation supplied
"""
if unit.lower() in "b bit bits".split():
return f"{bytes*8} {unit}"
unitN = unit[0].upper()+unit[1:].replace("s","") # Normalised
reference = {"Kb Kib Kibibit Kilobit": (7, 1),
"KB KiB Kibibyte Kilobyte": (10, 1),
"Mb Mib Mebibit Megabit": (17, 2),
"MB MiB Mebibyte Megabyte": (20, 2),
"Gb Gib Gibibit Gigabit": (27, 3),
"GB GiB Gibibyte Gigabyte": (30, 3),
"Tb Tib Tebibit Terabit": (37, 4),
"TB TiB Tebibyte Terabyte": (40, 4),
"Pb Pib Pebibit Petabit": (47, 5),
"PB PiB Pebibyte Petabyte": (50, 5),
"Eb Eib Exbibit Exabit": (57, 6),
"EB EiB Exbibyte Exabyte": (60, 6),
"Zb Zib Zebibit Zettabit": (67, 7),
"ZB ZiB Zebibyte Zettabyte": (70, 7),
"Yb Yib Yobibit Yottabit": (77, 8),
"YB YiB Yobibyte Yottabyte": (80, 8),
}
key_list = '\n'.join([" b Bit"] + [x for x in reference.keys()]) +"\n"
if unitN not in key_list:
raise IndexError(f"\n\nConversion unit must be one of:\n\n{key_list}")
units, divisors = [(k,v) for k,v in reference.items() if unitN in k][0]
if SI:
divisor = 1000**divisors[1]/8 if "bit" in units else 1000**divisors[1]
else:
divisor = float(1 << divisors[0])
value = bytes / divisor
if value != 1 and len(unitN) > 3:
unitN += "s" # Create plural unit of measure
return "{:,.0f}".format(value) + " " + unitN
# Tests
>>> assert format_bytes(1,"b") == '8 b'
>>> assert format_bytes(1,"bits") == '8 bits'
>>> assert format_bytes(1024, "kilobyte") == "1 Kilobyte"
>>> assert format_bytes(1024, "kB") == "1 KB"
>>> assert format_bytes(7141000, "mb") == '54 Mb'
>>> assert format_bytes(7141000, "mib") == '54 Mib'
>>> assert format_bytes(7141000, "Mb") == '54 Mb'
>>> assert format_bytes(7141000, "MB") == '7 MB'
>>> assert format_bytes(7141000, "mebibytes") == '7 Mebibytes'
>>> assert format_bytes(7141000, "gb") == '0 Gb'
>>> assert format_bytes(1000000, "kB") == '977 KB'
>>> assert format_bytes(1000000, "kB", SI=True) == '1,000 KB'
>>> assert format_bytes(1000000, "kb") == '7,812 Kb'
>>> assert format_bytes(1000000, "kb", SI=True) == '8,000 Kb'
>>> assert format_bytes(125000, "kb") == '977 Kb'
>>> assert format_bytes(125000, "kb", SI=True) == '1,000 Kb'
>>> assert format_bytes(125*1024, "kb") == '1,000 Kb'
>>> assert format_bytes(125*1024, "kb", SI=True) == '1,024 Kb'
Here is what I use:
import math
def convert_size(size_bytes):
if size_bytes == 0:
return "0B"
size_name = ("B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB")
i = int(math.floor(math.log(size_bytes, 1024)))
p = math.pow(1024, i)
s = round(size_bytes / p, 2)
return "%s %s" % (s, size_name[i])
NB : size should be sent in Bytes.
Just in case anyone's searching for the reverse of this problem (as I sure did) here's what works for me:
def get_bytes(size, suffix):
size = int(float(size))
suffix = suffix.lower()
if suffix == 'kb' or suffix == 'kib':
return size << 10
elif suffix == 'mb' or suffix == 'mib':
return size << 20
elif suffix == 'gb' or suffix == 'gib':
return size << 30
return False
Here it is:
def convert_bytes(size):
for x in ['bytes', 'KB', 'MB', 'GB', 'TB']:
if size < 1024.0:
return "%3.1f %s" % (size, x)
size /= 1024.0
return size
Here is the compact function to calculate size
def GetHumanReadable(size,precision=2):
suffixes=['B','KB','MB','GB','TB']
suffixIndex = 0
while size > 1024 and suffixIndex < 4:
suffixIndex += 1 #increment the index of the suffix
size = size/1024.0 #apply the division
return "%.*f%s"%(precision,size,suffixes[suffixIndex])
For more detailed output and vice versa operation please refer: http://code.activestate.com/recipes/578019-bytes-to-human-human-to-bytes-converter/
Here my two cents, which permits casting up and down, and adds customizable precision:
def convertFloatToDecimal(f=0.0, precision=2):
'''
Convert a float to string of decimal.
precision: by default 2.
If no arg provided, return "0.00".
'''
return ("%." + str(precision) + "f") % f
def formatFileSize(size, sizeIn, sizeOut, precision=0):
'''
Convert file size to a string representing its value in B, KB, MB and GB.
The convention is based on sizeIn as original unit and sizeOut
as final unit.
'''
assert sizeIn.upper() in {"B", "KB", "MB", "GB"}, "sizeIn type error"
assert sizeOut.upper() in {"B", "KB", "MB", "GB"}, "sizeOut type error"
if sizeIn == "B":
if sizeOut == "KB":
return convertFloatToDecimal((size/1024.0), precision)
elif sizeOut == "MB":
return convertFloatToDecimal((size/1024.0**2), precision)
elif sizeOut == "GB":
return convertFloatToDecimal((size/1024.0**3), precision)
elif sizeIn == "KB":
if sizeOut == "B":
return convertFloatToDecimal((size*1024.0), precision)
elif sizeOut == "MB":
return convertFloatToDecimal((size/1024.0), precision)
elif sizeOut == "GB":
return convertFloatToDecimal((size/1024.0**2), precision)
elif sizeIn == "MB":
if sizeOut == "B":
return convertFloatToDecimal((size*1024.0**2), precision)
elif sizeOut == "KB":
return convertFloatToDecimal((size*1024.0), precision)
elif sizeOut == "GB":
return convertFloatToDecimal((size/1024.0), precision)
elif sizeIn == "GB":
if sizeOut == "B":
return convertFloatToDecimal((size*1024.0**3), precision)
elif sizeOut == "KB":
return convertFloatToDecimal((size*1024.0**2), precision)
elif sizeOut == "MB":
return convertFloatToDecimal((size*1024.0), precision)
Add TB, etc, as you wish.
UNITS = {1000: ['KB', 'MB', 'GB'],
1024: ['KiB', 'MiB', 'GiB']}
def approximate_size(size, flag_1024_or_1000=True):
mult = 1024 if flag_1024_or_1000 else 1000
for unit in UNITS[mult]:
size = size / mult
if size < mult:
return '{0:.3f} {1}'.format(size, unit)
approximate_size(2123, False)
Source: Stackoverflow.com