Python Sortedcontainers Save

Python Sorted Container Types: Sorted List, Sorted Dict, and Sorted Set

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Python Sorted Containers

Sorted Containers_ is an Apache2 licensed sorted collections library_, written in pure-Python, and fast as C-extensions.

Python's standard library is great until you need a sorted collections type. Many will attest that you can get really far without one, but the moment you really need a sorted list, sorted dict, or sorted set, you're faced with a dozen different implementations, most using C-extensions without great documentation and benchmarking.

In Python, we can do better. And we can do it in pure-Python!

.. code-block:: python

>>> from sortedcontainers import SortedList
>>> sl = SortedList(['e', 'a', 'c', 'd', 'b'])
>>> sl
SortedList(['a', 'b', 'c', 'd', 'e'])
>>> sl *= 10_000_000
>>> sl.count('c')
>>> sl[-3:]
['e', 'e', 'e']
>>> from sortedcontainers import SortedDict
>>> sd = SortedDict({'c': -3, 'a': 1, 'b': 2})
>>> sd
SortedDict({'a': 1, 'b': 2, 'c': -3})
>>> sd.popitem(index=-1)
('c', -3)
>>> from sortedcontainers import SortedSet
>>> ss = SortedSet('abracadabra')
>>> ss
SortedSet(['a', 'b', 'c', 'd', 'r'])
>>> ss.bisect_left('c')

All of the operations shown above run in faster than linear time. The above demo also takes nearly a gigabyte of memory to run. When the sorted list is multiplied by ten million, it stores ten million references to each of "a" through "e". Each reference requires eight bytes in the sorted container. That's pretty hard to beat as it's the cost of a pointer to each object. It's also 66% less overhead than a typical binary tree implementation (e.g. Red-Black Tree, AVL-Tree, AA-Tree, Splay-Tree, Treap, etc.) for which every node must also store two pointers to children nodes.

Sorted Containers_ takes all of the work out of Python sorted collections - making your deployment and use of Python easy. There's no need to install a C compiler or pre-build and distribute custom extensions. Performance is a feature and testing has 100% coverage with unit tests and hours of stress.

.. _Sorted Containers: .. _sorted collections library:


Alex Martelli, Fellow of the Python Software Foundation_

"Good stuff! ... I like the simple, effective implementation_ idea of splitting the sorted containers into smaller "fragments" to avoid the O(N) insertion costs."

Jeff Knupp, author of Writing Idiomatic Python and Python Trainer_

"That last part, "fast as C-extensions," was difficult to believe. I would need some sort of Performance Comparison_ to be convinced this is true. The author includes this in the docs. It is."

Kevin Samuel, Python and Django Trainer_

I'm quite amazed, not just by the code quality (it's incredibly readable and has more comment than code, wow), but the actual amount of work you put at stuff that is not code: documentation, benchmarking, implementation explanations. Even the git log is clean and the unit tests run out of the box on Python 2 and 3.

Mark Summerfield, a short plea for Python Sorted Collections_

Python's "batteries included" standard library seems to have a battery missing. And the argument that "we never had it before" has worn thin. It is time that Python offered a full range of collection classes out of the box, including sorted ones.

Sorted Containers_ is used in popular open source projects such as: Zipline, an algorithmic trading library from Quantopian; Angr, a binary analysis platform from UC Santa Barbara; Trio, an async I/O library; and Dask Distributed, a distributed computation library supported by Continuum Analytics.

.. _Fellow of the Python Software Foundation: .. _simple, effective implementation: .. _author of Writing Idiomatic Python and Python Trainer: .. _Python and Django Trainer: .. _Python Sorted Collections: .. _Zipline: .. _Angr: .. _Trio: .. _Dask Distributed:


  • Pure-Python
  • Fully documented
  • Benchmark comparison (alternatives, runtimes, load-factors)
  • 100% test coverage
  • Hours of stress testing
  • Performance matters (often faster than C implementations)
  • Compatible API (nearly identical to older blist and bintrees modules)
  • Feature-rich (e.g. get the five largest keys in a sorted dict: d.keys()[-5:])
  • Pragmatic design (e.g. SortedSet is a Python set with a SortedList index)
  • Developed on Python 3.10
  • Tested with CPython 3.7, 3.8, 3.9, 3.10 and PyPy3
  • Tested on Linux, Mac OSX, and Windows

.. image:: :target:

.. image:: :target:


Installing Sorted Containers_ is simple with pip <>_::

$ pip install sortedcontainers

You can access documentation in the interpreter with Python's built-in help function. The help works on modules, classes and methods in Sorted Containers_.

.. code-block:: python

>>> import sortedcontainers
>>> help(sortedcontainers)
>>> from sortedcontainers import SortedDict
>>> help(SortedDict)
>>> help(SortedDict.popitem)


Complete documentation for Sorted Containers_ is available at

User Guide ..........

The user guide provides an introduction to Sorted Containers_ and extensive performance comparisons and analysis.

  • Introduction_
  • Performance Comparison_
  • Load Factor Performance Comparison_
  • Runtime Performance Comparison_
  • Simulated Workload Performance Comparison_
  • Performance at Scale_

.. _Introduction: .. _Performance Comparison: .. _Load Factor Performance Comparison: .. _Runtime Performance Comparison: .. _Simulated Workload Performance Comparison: .. _Performance at Scale:

Community Guide ...............

The community guide provides information on the development of Sorted Containers_ along with support, implementation, and history details.

  • Development and Support_
  • Implementation Details_
  • Release History_

.. _Development and Support: .. _Implementation Details: .. _Release History:

API Documentation .................

The API documentation provides information on specific functions, classes, and modules in the Sorted Containers_ package.

  • Sorted List_
  • Sorted Dict_
  • Sorted Set_

.. _Sorted List: .. _Sorted Dict: .. _Sorted Set:


  • Python Sorted Collections | PyCon 2016 Talk_
  • SF Python Holiday Party 2015 Lightning Talk_
  • DjangoCon 2015 Lightning Talk_

.. _Python Sorted Collections | PyCon 2016 Talk: .. _SF Python Holiday Party 2015 Lightning Talk: .. _DjangoCon 2015 Lightning Talk:


  • Sorted Containers Documentation_
  • Sorted Containers at PyPI_
  • Sorted Containers at Github_
  • Sorted Containers Issue Tracker_

.. _Sorted Containers Documentation: .. _Sorted Containers at PyPI: .. _Sorted Containers at Github: .. _Sorted Containers Issue Tracker:

Sorted Containers License

Copyright 2014-2019 Grant Jenks

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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