hwms / cyordereddict

Cython implementation of OrderedDict

cyordereddict

The Python standard library's OrderedDict ported to Cython. A drop-in replacement that is 2-6x faster.

Install:

pip install cyordereddict

Dependencies:

CPython (2.6, 2.7, 3.3 or 3.4) and a C compiler. Cython is only required for the dev version.

Use:

from cyordereddict import OrderedDict

Benchmarks:

Python 2.7:

Test	Code	Ratio (stdlib / cython)
__init__ empty	OrderedDict()	1.8
__init__ list	OrderedDict(list_data)	4.8
__init__ dict	OrderedDict(dict_data)	4.6
__setitem__	ordereddict[0] = 0	8.6
__getitem__	ordereddict[0]	3
update	ordereddict.update(dict_data)	5.5
__iter__	list(ordereddict)	5.6
items	ordereddict.items()	5.9
__contains__	0 in ordereddict	2.3

Python 3.4:

Test	Code	Ratio (stdlib / cython)
__init__ empty	OrderedDict()	1.5
__init__ list	OrderedDict(list_data)	3.9
__init__ dict	OrderedDict(dict_data)	4.2
__setitem__	ordereddict[0] = 0	8.4
__getitem__	ordereddict[0]	2.9
update	ordereddict.update(dict_data)	6.5
__iter__	list(ordereddict)	2.3
items	list(ordereddict.items())	2.1
__contains__	0 in ordereddict	2.3

To run these yourself, use cyordereddict.benchmark()

Cavaets:

cyorderedddict.OrderedDict is an extension type (similar to the built-in dict) instead of a Python class. This is necessary for speed, but means that in a few pathological cases its behavior will differ from collections.OrderedDict:

• The inspect module does not work on cyorderedddict.OrderedDict methods.
• Extension types use slots instead of dictionaries, so you cannot add custom attributes without making a subclass (e.g., OrderedDict.foo = 'bar' will fail).

You can do anything else you might do with an OrderedDict, including subclassing: everything else passes the collections.OrderedDict test suite. We based the Cython code directly on the Python standard library, and thus use separate code bases for Python 2 and 3, specifically to reduce the potential for introducing new bugs.

License:

MIT. Based on the Python standard library, which is under the Python Software Foundation License.