timlnx/bitmath — 96 Stars

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#files #filesystem #math-library #python #python3 #size-calculation #sizes

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bitmath =======

Free software: MIT License
Documentation: https://bitmath.readthedocs.io/en/latest/
Source: https://github.com/timlnx/bitmath
Bugs: https://github.com/timlnx/bitmath/issues
Contributing: https://bitmath.readthedocs.io/en/latest/contributing.html

bitmath <https://bitmath.readthedocs.io/en/latest/>_ simplifies many facets of interacting with file sizes in various units. Originally focusing on file size unit conversion, functionality now includes:

Converting between SI and NIST prefix units (`kB to GiB)


Converting between units of the same type (SI to SI, or NIST to NIST)
Full NIST unit coverage including ZiB, YiB, Zib, and Yib

Automatic human-readable prefix selection (like in hurry.filesize _)


Basic arithmetic operations (subtracting 42KiB from 50GiB)

Capacity math with floor division, modulo, and divmod (GiB(1) // MiB(300), GiB(1) % MiB(300))

Rich comparison operations (1024 Bytes == 1KiB)

Bitwise operations (<<, >>, &, |, ^)

Rounding via math.floor, math.ceil, and round


Reading a device's storage capacity (Linux/macOS support only)
String parsing, including flexible non-strict parsing of ambiguous input
Sorting

Summing iterables via built-in sum or bitmath.sum for unit-normalised results

f-string and format support via the standard Python formatting protocol

argparse _

  integration as a custom type

In addition to the conversion and math operations, bitmath provides human readable representations of values which are suitable for use in interactive shells as well as larger scripts and applications. The format produced for these representations is customizable via the functionality included in stdlibs string.format _.

In discussion we will refer to the NIST units primarily. I.e., instead of "megabyte" we will refer to "mebibyte". The former is 10^3 = 1,000,000 bytes, whereas the second is 2^20 = 1,048,576 bytes. When you see file sizes or transfer rates in your web browser, most of the time what you're really seeing are the base-2 sizes/rates.

Don't Forget! The source for bitmath is available on GitHub _.

And did we mention there are nearly 300 unit tests? Check them out for yourself _.

Running the tests should be as simple as calling the ci target in the Makefile: make ci. Please file a bug report if you run into issues.



Installation ============
.. admonition:: Seeking a Debian Maintainer

bitmath is not currently packaged for Debian or Ubuntu. If you're interested in maintaining the package for those distributions, please see issue #117 _.


Requires Python 3.9 or newer. No runtime dependencies outside the standard library.
PyPI (the typical path):
.. code-block:: bash
pip install bitmath
Fedora and EPEL
.. code-block:: bash
sudo dnf install python3-bitmath
From source
.. code-block:: bash
git clone https://github.com/timlnx/bitmath.git    pip install ./bitmath
Documentation =============

The main documentation lives at https://bitmath.readthedocs.io/en/latest/ _.


Topics include:

The bitmath Module


  * Utility Functions
  * Context Managers
  * Module Variables
  *

argparse

 integration

The bitmath command-line Tool


Classes

  * Initializing
  * Available Classes
  * Class Methods
Instances

  * Instance Attributes
  * Instance Methods
  * Instance Properties
  * The Formatting Mini-Language
Getting Started

  * Tables of Supported Operations
  * Basic Math
  * Unit Conversion
  * Rich Comparison
  * Sorting
Real Life Examples

  * Download Speeds
  * Calculating how many files fit on a device
  * Printing Human-Readable File Sizes in Python
  * Calculating Linux BDP and TCP Window Scaling
Contributing to bitmath
Appendices

  * Rules for Math
  * On Units
  * Who uses Bitmath
  * Related Projects
NEWS

Copyright

Examples ========
Arithmetic 

.. code-block:: python
>>> import bitmath    >>> log_size = bitmath.kB(137.4)    >>> logzippedsize = bitmath.Byte(987)    >>> print("Compression saved %s space" % (logsize - logzipped_size))    Compression saved 136.413kB space    >>> thumb_drive = bitmath.GiB(12)    >>> song_size = bitmath.MiB(5)    >>> songsperdrive = thumbdrive / songsize    >>> print(songsperdrive)    2457.6
Capacity Planning

Floor division (//), modulo (%), and divmod() are handy for chunk-and-remainder capacity math. bm1 // bm2 returns an int (how many whole chunks fit); bm1 % bm2 returns a bitmath of the left-hand operand's type (the leftover).


.. code-block:: python
>>> from bitmath import GiB, MiB, TiB    >>> disk = GiB(1)    >>> chunk = MiB(300)
>>> disk // chunk        # how many whole 300 MiB chunks fit?    3    >>> disk % chunk         # leftover, typed as the LHS (GiB)    GiB(0.12109375)    >>> divmod(disk, chunk)  # both at once    (3, GiB(0.12109375))

Re-express the remainder in a human-readable unit with bestprefix() (or coerce directly with toMiB(), etc.):


.. code-block:: python
>>> (GiB(1) % MiB(300)).best_prefix()    MiB(124.0)

Pair with the bitmath.format context manager for clean reporting across a block of capacity calculations:


.. code-block:: python
>>> import bitmath    >>> volume = TiB(1)    >>> block = GiB(7)    >>> with bitmath.format(fmt_str="{value:.2f} {unit}", bestprefix=True):    ...     whole, leftover = divmod(volume, block)    ...     print(f"{whole} whole blocks of {block} fit in {volume}")    ...     print(f"leftover: {leftover}")    146 whole blocks of 7.00 GiB fit in 1.00 TiB    leftover: 2.00 GiB

The identity (a // b) * b + (a % b) == a holds, so divmod round-trips.


Convert Units 

File size unit conversion:
.. code-block:: python
>>> from bitmath import *    >>> dvd_size = GiB(4.7)    >>> print("DVD Size in MiB: %s" % dvdsize.toMiB())    DVD Size in MiB: 4812.8 MiB
Select a human-readable unit 

.. code-block:: python
>>> small_number = kB(100)    >>> uglynumber = smallnumber.to_TiB()
>>> print(ugly_number)    9.09494701773e-08 TiB    >>> print(uglynumber.bestprefix())    97.65625 KiB
Rich Comparison 

.. code-block:: python
>>> cd_size = MiB(700)    >>> cdsize > dvdsize    False    >>> cdsize < dvdsize    True    >>> MiB(1) == KiB(1024)    True    >>> MiB(1) <= KiB(1024)    True
Sorting 

.. code-block:: python
>>> sizes = [KiB(7337.0), KiB(1441.0), KiB(2126.0), KiB(2178.0),                      KiB(2326.0), KiB(4003.0), KiB(48.0), KiB(1770.0),                      KiB(7892.0), KiB(4190.0)]
>>> print(sorted(sizes))    [KiB(48.0), KiB(1441.0), KiB(1770.0), KiB(2126.0), KiB(2178.0),    KiB(2326.0), KiB(4003.0), KiB(4190.0), KiB(7337.0), KiB(7892.0)]
Custom Formatting 

Use of the custom formatting system
All of the available instance properties

Example:
.. code-block:: python
>>> longer_format = """Formatting attributes for %s       ...: This instances prefix unit is {unit}, which is a {system} type unit       ...: The unit value is {value}       ...: This value can be truncated to just 1 digit of precision: {value:.1f}       ...: In binary this looks like: {binary}       ...: The prefix unit is derived from a base of {base}       ...: Which is raised to the power {power}       ...: There are {bytes} bytes in this instance       ...: The instance is {bits} bits large       ...: bytes/bits without trailing decimals: {bytes:.0f}/{bits:.0f}""" % str(ugly_number)
>>> print(uglynumber.format(longerformat))    Formatting attributes for 5.96046447754 MiB    This instances prefix unit is MiB, which is a NIST type unit    The unit value is 5.96046447754    This value can be truncated to just 1 digit of precision: 6.0    In binary this looks like: 0b10111110101111000010000000    The prefix unit is derived from a base of 2    Which is raised to the power 20    There are 6250000.0 bytes in this instance    The instance is 50000000.0 bits large    bytes/bits without trailing decimals: 6250000/50000000
Utility Functions 

bitmath.getsize()
.. code-block:: python
>>> print(bitmath.getsize('python-bitmath.spec'))    3.7060546875 KiB
bitmath.parse_string()
Parse a string with standard units:
.. code-block:: python
>>> import bitmath    >>> advd = bitmath.parsestring("4.7 GiB")    >>> print(type(a_dvd))    <class 'bitmath.GiB'>    >>> print(a_dvd)    4.7 GiB
bitmath.parsestringunsafe()
Parse a string with ambiguous units:
.. code-block:: python
>>> import bitmath    >>> agig = bitmath.parsestring_unsafe("1gb")    >>> print(type(a_gig))    <class 'bitmath.GB'>    >>> a_gig == bitmath.GB(1)    True    >>> bitmath.parsestringunsafe('1gb') == bitmath.parsestringunsafe('1g')    True
bitmath.querydevicecapacity()
.. code-block:: python
>>> import bitmath    >>> with open('/dev/sda') as fp:    ...     rootdisk = bitmath.querydevice_capacity(fp)    ...     print(rootdisk.bestprefix())    ...    238.474937439 GiB
bitmath.listdir()
.. code-block:: python
>>> for i in bitmath.listdir('./tests/', followlinks=True, relpath=True, bestprefix=True):    ...     print(i)    ...    ('tests/testfilesize.py', KiB(9.2900390625))    ('tests/testbasicmath.py', KiB(7.1767578125))    ('tests/init.py', KiB(1.974609375))    ('tests/testbitwiseoperations.py', KiB(2.6376953125))    ('tests/testcontextmanager.py', KiB(3.7744140625))    ('tests/test_representation.py', KiB(5.2568359375))    ('tests/test_properties.py', KiB(2.03125))    ('tests/test_instantiating.py', KiB(3.4580078125))    ('tests/testfuturemath.py', KiB(2.2001953125))    ('tests/testbestprefix_BASE.py', KiB(2.1044921875))    ('tests/testrichcomparison.py', KiB(3.9423828125))    ('tests/testbestprefix_NIST.py', KiB(5.431640625))    ('tests/testuniquetestcase_names.sh', Byte(311.0))    ('tests/.coverage', KiB(3.1708984375))    ('tests/testbestprefix_SI.py', KiB(5.34375))    ('tests/testtobuiltinconversion.py', KiB(1.798828125))    ('tests/testtoType_conversion.py', KiB(8.0185546875))    ('tests/test_sorting.py', KiB(4.2197265625))    ('tests/listdirsymlinks/10bytefilelink', Byte(10.0))    ('tests/listdirsymlinks/depth1/depth2/10byte_file', Byte(10.0))    ('tests/listdirnosymlinks/depth1/depth2/10byte_file', Byte(10.0))    ('tests/listdirnosymlinks/depth1/depth2/1024byte_file', KiB(1.0))    ('tests/file_sizes/kbytes.test', KiB(1.0))    ('tests/file_sizes/bytes.test', Byte(38.0))    ('tests/listdir/10bytefile', Byte(10.0))
Formatting 

.. code-block:: python
>>> with bitmath.format(fmt_str="[{value:.3f}@{unit}]"):    ...     for i in bitmath.listdir('./tests/', followlinks=True, relpath=True, bestprefix=True):    ...         print(i[1])    ...    [9.290@KiB]    [7.177@KiB]    [1.975@KiB]    [2.638@KiB]    [3.774@KiB]    [5.257@KiB]    [2.031@KiB]    [3.458@KiB]    [2.200@KiB]    [2.104@KiB]    [3.942@KiB]    [5.432@KiB]    [311.000@Byte]    [3.171@KiB]    [5.344@KiB]    [1.799@KiB]    [8.019@KiB]    [4.220@KiB]    [10.000@Byte]    [10.000@Byte]    [10.000@Byte]    [1.000@KiB]    [1.000@KiB]    [38.000@Byte]    [10.000@Byte]

argparse Integration

A self-contained example showing how to use bitmath as an argparse argument type is available in the Integration Examples examples.html#argparse>` chapter of the documentation.

.. code-block:: python

import argparse import bitmath

def BitmathType(value): try: return bitmath.parse_string(value) except ValueError: raise argparse.ArgumentTypeError( f"{value!r} is not a recognized bitmath unit string" )

parser = argparse.ArgumentParser() parser.add_argument('--block-size', type=BitmathType, required=True) args = parser.parse_args(['--block-size', '10MiB']) print(args.block_size) # 10.0 MiB

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