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cynamedtuple-0.1.0
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مشاهده بیشترتوضیحات
Memory efficient and fast namedtuple implementation using Cython
| ویژگی | مقدار |
|---|---|
| سیستم عامل | - |
| نام فایل | cynamedtuple-0.1.0 |
| نام | cynamedtuple |
| نسخه کتابخانه | 0.1.0 |
| نگهدارنده | [] |
| ایمیل نگهدارنده | [] |
| نویسنده | Egor Dranischnikow |
| ایمیل نویسنده | - |
| آدرس صفحه اصلی | https://github.com/realead/cynamedtuple |
| آدرس اینترنتی | https://pypi.org/project/cynamedtuple/ |
| مجوز | MIT |
# cynamedtuple
Memory efficient and fast `namedtuple` implementation using `Cython`.
## Installation
To install last released version:
pip install cynamedtuple
As `cynamedtuple` uses `Cython` under the hood, right C-compler/tool-chain is needed in order to be able to create `cynamedtuple`s.
To install the most current version use:
pip install https://github.com/realead/cynamedtuple/zipball/master
The necessary `Cython`-module will be installed as well, if not already in the installation.
## Usage
When providing the types of fields, the resulting tuple is not only named but also typed, i.e. the underlying fields backed by corresponding c-types thus needing less memory:
from cynamedtuple import typed_namedtuple
MyStruct = typed_namedtuple("MyStruct", dict(a="int", b="int", c="int"), defaults=[2,3])
s = MyStruct(5)
print(s.a, s.b, s.c) # results in 5 2 3
print(s[0], s[1], s[-1]) # results in 5 2 3
For Python versions with non-ordered `dict`s (i.e. prior to Py3.6), version with name-type-pairs iterable can be used:
...
typed_namedtuple("MyStruct", [("a","int"), ("b","int"), ("c","int")])
...
When the fields cannot be statically typed, `untyped_namedtuple` can be used, which uses slightly less memory and is somewhat faster than Python's original `namedtuple`:
from cynamedtuple import untyped_namedtuple
MyStruct = untyped_namedtuple("MyStruct", ["a", "b", "c"], defaults=[2,3])
s = MyStruct(5)
print(s.a, s.b, s.c) # results in 5 2 3
print(s[0], s[1], s[-1]) # results in 5 2 3
## Performance
Let's compare the performance of the following implementation
P=collections.namedtuple("P",["a", "b"])
T=cynamedtuple.typed_namedtuple("T", [("a", "int"), ("b", "int")])
U=cynamedtuple.untyped_namedtuple("U", ["a", "b"])
with the built-in (unnamed) `tuple`.
### Memory usage
Memory usage depends on the used types, using `int` instead of Python's integer means 3-4 times smaller memory footprint. For `1e7` elements in a list following memory was used:
| Class | Used memory (in MB)|
|-----------|--------------------|
|typed(T) | 308 |
|untyped(U) | 927 |
|Python's(P)| 1082 |
|tuple | 1006 |
### Timings
#### Creation
For creation of `1e6` elements, typed cynamedtuple is almost as fast as usual tuple and about 4 times faster than Python's `namedtuple`:
| Class | Times |
|------------|--------------------|
|typed(T) | 128 ms |
|untyped(U) | 171 ms |
|Python's(P) | 504 ms |
|tuple | 118 ms |
#### Accessing fields
For accessing a field, typed and untyped versions are about 30% faster than Python's `namedtuple` but slightly slower than the usual `tuple`:
| Class | Times |
|-----------|--------------------|
|typed(T) | 51.5 ns |
|untyped(U) | 45.5 ns |
|Python's(P)| 68.4 ns |
|tuple | 49.9 ns |
#### Accessing via index
Warning: `cynamedtuple`s aren't optimized for access via index - it is linear in number of fields, thus should not be used if there are many fields.
## Producing pyx-code
Under the hood cynamedtuple uses string code snippets from Cython (aka `cython.inline`), and with that some constrains come into play:
* Cython doesn't not yet supporting any cimports/includes from string code snippets
* it is not possible to define any types via `ctypedef` e.g. `ctypedef int myint` and use them in a `cynamedtuple`, thus the types of `cynamedtuple` are limited to the built-in types.
A workaround is to use `typed_namedtuple_cycode` to produce the Cython code and to build a cython module from it. Use `cython_header`-argument to insert needed definitions, e.g.
typed_namedtuple_cycode("A", (("a", "myint"),), cython_header = ["ctypedef int myint"])
will yield the following cython-code:
ctypedef int myint
cdef class A:
cdef public myint a
def __init__(self,a):
self.a = a
def __getitem__(self, i):
if i==0 or i==-1: return self.a
raise IndexError('tuple index out of range')
There is also `untyped_namedtuple_cycode`-function as well.
## Trivia:
* This project was inspired by the following SO-question: https://stackoverflow.com/q/65159938/5769463.
* While Python's `namedtuple` was an inspiration, `cynamedtuple`isn't a simple drop-in replacement.
* While cnamedtuple (https://pypi.org/project/cnamedtuple/) is all about speed, `cynamedtuple` is more about smaller memory footprint.
## History:
* 0.1.0: 13.12.2020:
* introducing basic functionality
نحوه نصب
نصب پکیج whl cynamedtuple-0.1.0:
pip install cynamedtuple-0.1.0.whl
نصب پکیج tar.gz cynamedtuple-0.1.0:
pip install cynamedtuple-0.1.0.tar.gz