views -- efficient tools for generators and sequences

The views module provides additions to the existing python comprehensions and generator expressions. (Chained) sequence views can be made using seq and generators can be chained with gen, as shown in the examples below.

Any feedback or suggestions are very welcome.

• Email: koos.zevenhoven@aalto.fi
• Twitter: @k7hoven

Getting Started

Requirements

• Python 3.6+

Installation

The package can be installed with pip (make sure you have it installed):

pip3 install git+http://github.com/k7hoven/views

Or if your default python is Python 3:

pip install git+http://github.com/k7hoven/views

Basic Usage

Basic introductory examples here, but they should get you started.

Sequence view comprehension syntax

You can change chain single objects and sequences into one sequence view. Use :: just like you would use * in tuple (un)packing. The resulting object supports slicing and indexing.

Example:

>>> from views import seq
>>> seq[::range(3), None, ::"abc", "Hi!"]
<sequence view 8: [0, 1, 2, None, 'a', 'b', 'c', 'Hi!'] >
>>> seq[::range(100)]
<sequence view 100: [0, 1, 2, 3, 4, ..., 96, 97, 98, 99] >

Generator comprehension syntax

Use like seq. The resulting object is a generator.

Example:

>>> from views import gen
>>> list(gen[::range(3), 3, 4, ::range(5,7), 7])
[0, 1, 2, 3, 4, 5, 6, 7]

Chaining sequences and generators/iterables

You can chain an arbitrary number of sequences with seq.chain(*sequences) and of generators with gen.chain(*iterables). The latter is equivalent to itertools.chain(*iterables).

Example:

>>> from views import seq, gen
>>> seq.chain([1, 2, 3], [4, 5, 6])
<sequence view 6: [1, 2, 3, 4, 5, 6] >
>>> list(gen.chain([1, 2, 3], [4, 5, 6]))
[1, 2, 3, 4, 5, 6]

Improved range objects

For a more capable and understandable replacement for the builtin range, you can use views.range, which takes any arguments the builtin function takes, or alternatively a first, second, ..., last[, step=step] argument list. Also the repr uses the more learning-friendly variant.

Examples:

>>> from views import range
>>> range(5)
range(0, ..., 4)
>>> range(1, 10, 3)
range(1, ..., 7, step=3)
>>> range(1, ..., 5)
range(1, ..., 5)
>>> range(1, 3, ..., 10)
range(1, ..., 9, step=2)
>>> range(2, ..., 15, step=3)
range(2, ..., 14, step=3)
>>> range(9, ..., 4, step=-1)
range(9, ..., 4, step=-1)

Have fun!