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pelper - python helper functions

Project Description

pelper – python helper functions to ease measuring, ignoring, caching, piping, functional helpers, and more for python 2.7, 3.4, and 3.5.

pelper contains useful helper functions, decorators, context managers - all the things that make your python life a tiny bit easier. pelper has no dependencies, has a coverage of 100%, and is well documented.


Pipe data through unix-like/elixir-like pipes:

>>> from pelper import pipe
>>> pipe("some datat, some data", set, (sorted, {"reverse": True}))
['t', 's', 'o', 'm', 'e', 'd', 'a', ',', ' ']

Pelper offers p-functions, i.e., functions where the first argument is data. There is pmap (like map, but works with pipel):

>>> from pelper import pipe, pmap
>>> pipe(
...     range(5),
...     (pmap, lambda x: x*x),
...     list)
[0, 1, 4, 9, 16]

…and also pfilter:

>>> from pelper import pipe, pfilter
>>> pipe(
...     range(5),
...     (pfilter, lambda x: x > 2),
...     list)
[3, 4]

Take n elements from iterables (useful if you can’t use the square bracket notation, e.g., if you’re using pipe)

>>> from pelper import take
>>> take("hello world", 5)
['h', 'e', 'l', 'l', 'o']

Take the n-th elements from iterables (useful if you can’t use the square bracket notation, e.g., if you’re using pipe)

>>> from pelper import nth
>>> nth(range(5), 2)

Flatten arbitrarily nested lists:

>>> from pelper import flatten
>>> flatten([1, [2, 2, [3, 3]]])
[1, 2, 2, 3, 3]

Measure the duration of a function:

>>> from pelper import print_duration
>>> @print_duration()
...  def f(n): pass

Measure the duration of a context:

>>> from pelper import print_duration
>>> with print_duration():
...     range(4)

Ignore exceptions:

>>> from pelper import ignored
>>> with ignored(OSError):
...     raise OSError()  # this is ignored

Cache already computed results of functions:

>>> from pelper import cache
>>> @cache
>>> def fib(n):
...     return 1 if n < 2 else fib(n-1) + fib(n-2)
>>> f(500)  # this would run for quite a wile without the cache decorator

Easier printing and formating:

>>> from pelper import printf
>>> printf("Hello {name}, I'm {something}", name="Alan", something="world")
Hello Alan, I'm world


pelper is only one file and has no dependencies. You can simply drop into your project and use it.

Or install it from pypi by running:

pip install pelper

Or install it from source by running:

pip install .


Use virtualenv for working on pelper. Install the dev requrirements via:

pip install -e requirements-dev.txt


pelper uses doctest, py.test, and tox for testing. It also has coverage.

You can run the tests for all supported versions of python and build and test the docs:


Run only the tests for the specified version of python:

tox -e py27,py34,py35

Alternatively just run tests for the current version of python:



Build the docs via:

cd docs
sphinx html
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pelper-0.1.0-py2.py3-none-any.whl (9.2 kB) Copy SHA256 Checksum SHA256 py2.py3 Wheel Jan 16, 2017
pelper-0.1.0.tar.gz (6.5 kB) Copy SHA256 Checksum SHA256 Source Jan 16, 2017

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