Useful Python Utils

Python Utils is a collection of small Python functions and classes which make common patterns shorter and easier. It is by no means a complete collection but it has served me quite a bit in the past and I will keep extending it.

One of the libraries using Python Utils is Django Utils.

Documentation is available at: https://python-utils.readthedocs.org/en/latest/

Links

• The source: https://github.com/WoLpH/python-utils
• Project page: https://pypi.python.org/pypi/python-utils
• Reporting bugs: https://github.com/WoLpH/python-utils/issues
• Documentation: https://python-utils.readthedocs.io/en/latest/
• My blog: https://wol.ph/

Requirements for installing:

For the Python 3+ release (i.e. v3.0.0 or higher) there are no requirements. For the Python 2 compatible version (v2.x.x) the six package is needed.

Installation:

The package can be installed through pip (this is the recommended method):

pip install python-utils

Or if pip is not available, easy_install should work as well:

easy_install python-utils

Or download the latest release from Pypi (https://pypi.python.org/pypi/python-utils) or Github.

Note that the releases on Pypi are signed with my GPG key (https://pgp.mit.edu/pks/lookup?op=vindex&search=0xE81444E9CE1F695D) and can be checked using GPG:

gpg –verify python-utils-<version>.tar.gz.asc python-utils-<version>.tar.gz

Quickstart

This module makes it easy to execute common tasks in Python scripts such as converting text to numbers and making sure a string is in unicode or bytes format.

Examples

To easily retry a block of code with a configurable timeout, you can use the time.timeout_generator:

>>> for i in time.timeout_generator(10):
...     try:
...         # Run your code here
...     except Exception as e:
...         # Handle the exception

Easy formatting of timestamps and calculating the time since:

>>> time.format_time('1')
'0:00:01'
>>> time.format_time(1.234)
'0:00:01'
>>> time.format_time(1)
'0:00:01'
>>> time.format_time(datetime.datetime(2000, 1, 2, 3, 4, 5, 6))
'2000-01-02 03:04:05'
>>> time.format_time(datetime.date(2000, 1, 2))
'2000-01-02'
>>> time.format_time(datetime.timedelta(seconds=3661))
'1:01:01'
>>> time.format_time(None)
'--:--:--'

>>> formatters.timesince(now)
'just now'
>>> formatters.timesince(now - datetime.timedelta(seconds=1))
'1 second ago'
>>> formatters.timesince(now - datetime.timedelta(seconds=2))
'2 seconds ago'
>>> formatters.timesince(now - datetime.timedelta(seconds=60))
'1 minute ago'

Converting your test from camel-case to underscores:

>>> camel_to_underscore('SpamEggsAndBacon')
'spam_eggs_and_bacon'

A convenient decorator to set function attributes using a decorator:

You can use:
>>> @decorators.set_attributes(short_description='Name')
... def upper_case_name(self, obj):
...     return ("%s %s" % (obj.first_name, obj.last_name)).upper()

Instead of:
>>> def upper_case_name(obj):
...     return ("%s %s" % (obj.first_name, obj.last_name)).upper()

>>> upper_case_name.short_description = 'Name'

Or to scale numbers:

>>> converters.remap(500, old_min=0, old_max=1000, new_min=0, new_max=100)
50

# Or with decimals:
>>> remap(decimal.Decimal('250.0'), 0.0, 1000.0, 0.0, 100.0)
Decimal('25.0')

To get the screen/window/terminal size in characters:

>>> terminal.get_terminal_size()
(80, 24)

That method supports IPython and Jupyter as well as regular shells, using blessings and other modules depending on what is available.

To extract a number from nearly every string:

>>> converters.to_int('spam15eggs')
15
>>> converters.to_int('spam')
0
>>> number = converters.to_int('spam', default=1)
1

To do a global import programmatically you can use the import_global function. This effectively emulates a from … import *

from python_utils.import_ import import_global

# The following is  the equivalent of `from some_module import *`
import_global('some_module')

Or add a correclty named logger to your classes which can be easily accessed:

class MyClass(Logged):
    def __init__(self):
        Logged.__init__(self)

my_class = MyClass()

# Accessing the logging method:
my_class.error('error')

# With formatting:
my_class.error('The logger supports %(formatting)s',
               formatting='named parameters')

# Or to access the actual log function (overwriting the log formatting can
# be done n the log method)
import logging
my_class.log(logging.ERROR, 'log')