https://github.com/jwodder/derange
Compress lists of integers to range objects
https://github.com/jwodder/derange
available-on-pypi compression connected-component connected-components consecutive distribution-sort gaps-and-islands interval python range sequential sorting sparse-array streak
Last synced: 3 months ago
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Compress lists of integers to range objects
- Host: GitHub
- URL: https://github.com/jwodder/derange
- Owner: jwodder
- License: mit
- Created: 2017-10-08T19:15:00.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2025-01-23T14:41:57.000Z (5 months ago)
- Last Synced: 2025-03-28T23:35:38.814Z (3 months ago)
- Topics: available-on-pypi, compression, connected-component, connected-components, consecutive, distribution-sort, gaps-and-islands, interval, python, range, sequential, sorting, sparse-array, streak
- Language: Python
- Size: 78.1 KB
- Stars: 4
- Watchers: 3
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.rst
- Changelog: CHANGELOG.md
- License: LICENSE
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`GitHub `_
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Do you have a list of integers? Do you want to know what ranges of consecutive
values the list covers? Do you need to solve a `gaps and islands
`_ problem outside of
SQL? Maybe you have a list of dates and need to find the longest streak of
consecutive days on which something happened. No? Why not? Well, either way,
the ``derange`` module is here for you, ready to solve all these problems and a
couple more.
Installation
============
``derange`` requires Python 3.8 or higher. Just use `pip
`_ for Python 3 (You have pip, right?) to install it::
python3 -m pip install derange
Examples
========
Condense commit years obtained from ``git log`` or the like into ``range``
objects:
>>> import derange
>>> derange.derange([2015, 2015, 2015, 2014, 2014, 2011, 2010, 2010, 2009, 2009])
[range(2009, 2012), range(2014, 2016)]
If the input is already sorted, you can condense it slightly faster with
``derange_sorted()``:
>>> derange.derange_sorted([2009, 2009, 2010, 2010, 2011, 2014, 2014, 2015, 2015, 2015])
[range(2009, 2012), range(2014, 2016)]
Organize non-integer values into closed intervals (represented as pairs of
endpoints) with ``deinterval()``:
>>> import datetime
>>> # deinterval() requires a callable for determining when two values are "adjacent":
>>> def within_24_hours(a,b):
... return abs(a-b) <= datetime.timedelta(hours=24)
...
>>> timestamps = [
... datetime.datetime(2017, 11, 2, 12, 0),
... datetime.datetime(2017, 11, 3, 11, 0),
... datetime.datetime(2017, 11, 4, 10, 0),
... datetime.datetime(2017, 11, 5, 9, 0),
... datetime.datetime(2017, 11, 6, 9, 0),
... datetime.datetime(2017, 11, 7, 10, 0),
... ]
>>> derange.deinterval(within_24_hours, timestamps)
[(datetime.datetime(2017, 11, 2, 12, 0), datetime.datetime(2017, 11, 6, 9, 0)), (datetime.datetime(2017, 11, 7, 10, 0), datetime.datetime(2017, 11, 7, 10, 0))]
… which also has a ``deinterval_sorted()`` variant:
>>> derange.deinterval_sorted(within_24_hours, timestamps)
[(datetime.datetime(2017, 11, 2, 12, 0), datetime.datetime(2017, 11, 6, 9, 0)), (datetime.datetime(2017, 11, 7, 10, 0), datetime.datetime(2017, 11, 7, 10, 0))]
>>> derange.deinterval_sorted(within_24_hours, reversed(timestamps))
Traceback (most recent call last):
...
ValueError: sequence not in ascending order
API
===
.. code:: python
derange.derange(iterable: Iterable[int]) -> List[range]
Convert a sequence of integers to a minimal list of ``range`` objects that
together contain all of the input elements.
Output is in strictly ascending order. Input need not be in order (but see
also ``derange_sorted()``). Duplicate input values are ignored.
.. code:: python
derange.derange_sorted(iterable: Iterable[int]) -> List[range]
Convert a *non-decreasing* sequence of integers to a minimal list of ``range``
objects that together contain all of the input elements. This is faster than
``derange()`` but only accepts sorted input.
.. code:: python
derange.deinterval(
adjacent: Callable[[T,T], bool],
iterable: Iterable[T],
) -> List[Tuple[T,T]]
Convert a sequence of totally-ordered values to a minimal list of closed
intervals (represented as pairs of endpoints) that together contain all of the
input elements. This is a generalization of ``derange()`` for arbitrary types.
Two input values will be placed in the same interval iff they are directly
adjacent or there exists a chain of adjacent input values connecting them,
where adjacency is defined by the given ``adjacent`` callable.
``adjacent`` will be called with two elements of ``iterable`` at a time to test
whether they should be placed in the same interval. The binary relation
implied by ``adjacent`` must be reflexive and symmetric, and for all ``x < y <
z``, if ``adjacent(x, z)`` is true, then both ``adjacent(x, y)`` and
``adjacent(y, z)`` must also be true.
Output is in strictly ascending order. Input need not be in order (but see
also ``deinterval_sorted()``). Duplicate input values are ignored.
Note that, unlike with ``range`` objects, intervals returned from
``deinterval()`` contain their upper bounds.
.. code:: python
derange.deinterval_sorted(
adjacent: Callable[[T,T], bool],
iterable: Iterable[T],
) -> List[Tuple[T,T]]
Convert a *non-decreasing* sequence of totally-ordered values to a minimal list
of closed intervals that together contain all of the input elements. This is
faster than ``deinterval()`` but only accepts sorted input.