bitmath 1.3.3.1

Description:

bitmath 1.3.3.1

bitmath
bitmath 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)
Automatic human-readable prefix selection (like in hurry.filesize)
Basic arithmetic operations (subtracting 42KiB from 50GiB)
Rich comparison operations (1024 Bytes == 1KiB)
bitwise operations (<<, >>, &, |, ^)
Reading a device’s storage capacity (Linux/OS X support only)
argparse
integration as a custom type
progressbar
integration as a better file transfer speed widget
String parsing
Sorting

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’s almost 200 unittests? Check them out for
yourself.


Installation
The easiest way to install bitmath is via dnf (or yum) if
you’re on a Fedora/RHEL based distribution. bitmath is available in
the main Fedora repositories, as well as the EPEL6
and EPEL7
repositories. There are now dual python2.x and python3.x releases
available.
Python 2.x:
$ sudo dnf install python2-bitmath
Python 3.x:
$ sudo dnf install python3-bitmath

Note
Upgrading: If you have the old python-bitmath package
installed presently, you could also run sudo dnf update python-bitmath instead

PyPi:
You could also install bitmath from PyPi if you like:
$ sudo pip install bitmath

Note
pip installs need pip >= 1.1. To workaround this, download
bitmath, from
PyPi and then pip install bitmath-x.y.z.tar.gz. See issue #57
for more information.

PPA:
Ubuntu Xenial, Wily, Vivid, Trusty, and Precise users can install
bitmath from the launchpad PPA:
$ sudo add-apt-repository ppa:tbielawa/bitmath
$ sudo apt-get update
$ sudo apt-get install python-bitmath
Source:
Or, if you want to install from source:
$ sudo python ./setup.py install
If you want the bitmath manpage installed as well:
$ sudo make install


Documentation
The main documentation lives at
http://bitmath.readthedocs.org/en/latest/.
Topics include:

The bitmath Module

Utility Functions
Context Managers
Module Variables
argparse integration
progressbar 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
>>> import bitmath
>>> log_size = bitmath.kB(137.4)
>>> log_zipped_size = bitmath.Byte(987)
>>> print "Compression saved %s space" % (log_size - log_zipped_size)
Compression saved 136.413kB space
>>> thumb_drive = bitmath.GiB(12)
>>> song_size = bitmath.MiB(5)
>>> songs_per_drive = thumb_drive / song_size
>>> print songs_per_drive
2457.6


Convert Units
File size unit conversion:
>>> from bitmath import *
>>> dvd_size = GiB(4.7)
>>> print "DVD Size in MiB: %s" % dvd_size.to_MiB()
DVD Size in MiB: 4812.8 MiB


Select a human-readable unit
>>> small_number = kB(100)
>>> ugly_number = small_number.to_TiB()

>>> print ugly_number
9.09494701773e-08 TiB
>>> print ugly_number.best_prefix()
97.65625 KiB


Rich Comparison
>>> cd_size = MiB(700)
>>> cd_size > dvd_size
False
>>> cd_size < dvd_size
True
>>> MiB(1) == KiB(1024)
True
>>> MiB(1) <= KiB(1024)
True


Sorting
>>> 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:
>>> 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 ugly_number.format(longer_format)
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()
>>> print bitmath.getsize('python-bitmath.spec')
3.7060546875 KiB
bitmath.parse_string()
Parse a string with standard units:
>>> import bitmath
>>> a_dvd = bitmath.parse_string("4.7 GiB")
>>> print type(a_dvd)
<class 'bitmath.GiB'>
>>> print a_dvd
4.7 GiB
bitmath.parse_string_unsafe()
Parse a string with ambiguous units:
>>> import bitmath
>>> a_gig = bitmath.parse_string_unsafe("1gb")
>>> print type(a_gig)
<class 'bitmath.GB'>
>>> a_gig == bitmath.GB(1)
True
>>> bitmath.parse_string_unsafe('1gb') == bitmath.parse_string_unsafe('1g')
True
bitmath.query_device_capacity()
>>> import bitmath
>>> with open('/dev/sda') as fp:
... root_disk = bitmath.query_device_capacity(fp)
... print root_disk.best_prefix()
...
238.474937439 GiB
bitmath.listdir()
>>> for i in bitmath.listdir('./tests/', followlinks=True, relpath=True, bestprefix=True):
... print i
...
('tests/test_file_size.py', KiB(9.2900390625))
('tests/test_basic_math.py', KiB(7.1767578125))
('tests/__init__.py', KiB(1.974609375))
('tests/test_bitwise_operations.py', KiB(2.6376953125))
('tests/test_context_manager.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/test_future_math.py', KiB(2.2001953125))
('tests/test_best_prefix_BASE.py', KiB(2.1044921875))
('tests/test_rich_comparison.py', KiB(3.9423828125))
('tests/test_best_prefix_NIST.py', KiB(5.431640625))
('tests/test_unique_testcase_names.sh', Byte(311.0))
('tests/.coverage', KiB(3.1708984375))
('tests/test_best_prefix_SI.py', KiB(5.34375))
('tests/test_to_built_in_conversion.py', KiB(1.798828125))
('tests/test_to_Type_conversion.py', KiB(8.0185546875))
('tests/test_sorting.py', KiB(4.2197265625))
('tests/listdir_symlinks/10_byte_file_link', Byte(10.0))
('tests/listdir_symlinks/depth1/depth2/10_byte_file', Byte(10.0))
('tests/listdir_nosymlinks/depth1/depth2/10_byte_file', Byte(10.0))
('tests/listdir_nosymlinks/depth1/depth2/1024_byte_file', KiB(1.0))
('tests/file_sizes/kbytes.test', KiB(1.0))
('tests/file_sizes/bytes.test', Byte(38.0))
('tests/listdir/10_byte_file', Byte(10.0))


Formatting
>>> 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
Example script using bitmath.integrations.BitmathType as an
argparser argument type:
import argparse
import bitmath
parser = argparse.ArgumentParser(
description="Arg parser with a bitmath type argument")
parser.add_argument('--block-size',
type=bitmath.integrations.BitmathType,
required=True)

results = parser.parse_args()
print "Parsed in: {PARSED}; Which looks like {TOKIB} as a Kibibit".format(
PARSED=results.block_size,
TOKIB=results.block_size.Kib)
If ran as a script the results would be similar to this:
$ python ./bmargparse.py --block-size 100MiB
Parsed in: 100.0 MiB; Which looks like 819200.0 Kib as a Kibibit


progressbar Integration
Use bitmath.integrations.BitmathFileTransferSpeed as a
progressbar file transfer speed widget to monitor download speeds:
import requests
import progressbar
import bitmath
import bitmath.integrations

FETCH = 'https://www.kernel.org/pub/linux/kernel/v3.0/patch-3.16.gz'
widgets = ['Bitmath Progress Bar Demo: ', ' ',
progressbar.Bar(marker=progressbar.RotatingMarker()), ' ',
bitmath.integrations.BitmathFileTransferSpeed()]

r = requests.get(FETCH, stream=True)
size = bitmath.Byte(int(r.headers['Content-Length']))
pbar = progressbar.ProgressBar(widgets=widgets, maxval=int(size),
term_width=80).start()
chunk_size = 2048
with open('/dev/null', 'wb') as fd:
for chunk in r.iter_content(chunk_size):
fd.write(chunk)
if (pbar.currval + chunk_size) < pbar.maxval:
pbar.update(pbar.currval + chunk_size)
pbar.finish()
If ran as a script the results would be similar to this:
$ python ./smalldl.py
Bitmath Progress Bar Demo: ||||||||||||||||||||||||||||||||||||||||| 1.58 MiB/s