search
HomeBackend DevelopmentPython TutorialAnalysis of common functions in the functools module in Python

1.partial

The first is the partial function, which can rebind the optional parameters of the function and generate a callable partial object:

>>> int('10') # 实际上等同于int('10', base=10)和int('10', 10) 
10 
>>> int('10', 2) # 实际上是int('10', base=2)的缩写 
2 
>>> from functools import partial 
>>> int2 = partial(int, 2) # 这里我没写base,结果就出错了 
>>> int2('10') 
Traceback (most recent call last): 
 File "<stdin>", line 1, in <module> 
TypeError: an integer is required 
>>> int2 = partial(int, base=2) # 把base参数绑定在int2这个函数里 
>>> int2(&#39;10&#39;) # 现在缺省参数base被设为2了 
2 
>>> int2(&#39;10&#39;, 3) # 没加base,结果又出错了 
Traceback (most recent call last): 
 File "<stdin>", line 1, in <module> 
TypeError: keyword parameter &#39;base&#39; was given by position and by name 
>>> int2(&#39;10&#39;, base=3) 
3 
>>> type(int2) 
<type &#39;functools.partial&#39;>

As can be seen from this, the only thing to note is that the optional parameter must write the parameter name.

2.update_wrapper
Then there is the update_wrapper function, which can copy the __name__, __module__, __doc__ and __dict__ of the encapsulated function to the encapsulating function:

#-*- coding: gbk -*- 
 
def thisIsliving(fun): 
 def living(*args, **kw): 
  return fun(*args, **kw) + &#39;活着就是吃嘛。&#39; 
 return living 
 
@thisIsliving 
def whatIsLiving(): 
 "什么是活着" 
 return &#39;对啊,怎样才算活着呢?&#39; 
 
print whatIsLiving() 
print whatIsLiving.__doc__ 
 
print 
 
from functools import update_wrapper 
def thisIsliving(fun): 
 def living(*args, **kw): 
  return fun(*args, **kw) + &#39;活着就是吃嘛。&#39; 
 return update_wrapper(living, fun) 
 
@thisIsliving 
def whatIsLiving(): 
 "什么是活着" 
 return &#39;对啊,怎样才算活着呢?&#39; 
 
print whatIsLiving() 
print whatIsLiving.__doc__

Result:

对啊,怎样才算活着呢?活着就是吃嘛。
None

对啊,怎样才算活着呢?活着就是吃嘛。
什么是活着

But it’s not much use, after all, it’s just a little Just wrote 4 lines of assignment statements.

3.wraps
Then there is the wraps function, which also encapsulates update_wrapper:

#-*- coding: gbk -*- 
 
from functools import wraps 
 
def thisIsliving(fun): 
 @wraps(fun) 
 def living(*args, **kw): 
  return fun(*args, **kw) + &#39;活着就是吃嘛。&#39; 
 return living 
 
@thisIsliving 
def whatIsLiving(): 
 "什么是活着" 
 return &#39;对啊,怎样才算活着呢?&#39; 
 
print whatIsLiving() 
print whatIsLiving.__doc__

The result is still the same:

对啊,怎样才算活着呢?活着就是吃嘛。
什么是活着

4.total_ordering
Finally, the total_ordering function gives a rich sorting method, using decorators simplifies operations. If used, a __lt__(), __le__(), __gt__(), or __ge__() must be defined in the class. An __eq__() method should be added to the class.

from functools import total_ordering

@total_ordering
class Student(object):
  def __init__(self, name):
    self.name = name

  def __eq__(self, other):
    return self.name.lower() == other.name.lower()

  def __lt__(self, other):
    return self.name.lower() < other.name.lower()

a = Student(&#39;dan&#39;)
b = Student(&#39;mink&#39;)

print a > b
print a
print sorted([b, a])

Print results

False
<__main__.Student object at 0x7f16ecb194d0>
[<__main__.Student object at 0x7f16ecb194d0>, <__main__.Student object at 0x7f16ecb195d0>]


##More For articles related to analysis of common functions of the functools module in Python, please pay attention to the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
What are some common reasons why a Python script might not execute on Unix?What are some common reasons why a Python script might not execute on Unix?Apr 28, 2025 am 12:18 AM

The reasons why Python scripts cannot run on Unix systems include: 1) Insufficient permissions, using chmod xyour_script.py to grant execution permissions; 2) Shebang line is incorrect or missing, you should use #!/usr/bin/envpython; 3) The environment variables are not set properly, and you can print os.environ debugging; 4) Using the wrong Python version, you can specify the version on the Shebang line or the command line; 5) Dependency problems, using virtual environment to isolate dependencies; 6) Syntax errors, using python-mpy_compileyour_script.py to detect.

Give an example of a scenario where using a Python array would be more appropriate than using a list.Give an example of a scenario where using a Python array would be more appropriate than using a list.Apr 28, 2025 am 12:15 AM

Using Python arrays is more suitable for processing large amounts of numerical data than lists. 1) Arrays save more memory, 2) Arrays are faster to operate by numerical values, 3) Arrays force type consistency, 4) Arrays are compatible with C arrays, but are not as flexible and convenient as lists.

What are the performance implications of using lists versus arrays in Python?What are the performance implications of using lists versus arrays in Python?Apr 28, 2025 am 12:10 AM

Listsare Better ForeflexibilityandMixdatatatypes, Whilearraysares Superior Sumerical Computation Sand Larged Datasets.1) Unselable List Xibility, MixedDatatypes, andfrequent elementchanges.2) Usarray's sensory -sensical operations, Largedatasets, AndwhenMemoryEfficiency

How does NumPy handle memory management for large arrays?How does NumPy handle memory management for large arrays?Apr 28, 2025 am 12:07 AM

NumPymanagesmemoryforlargearraysefficientlyusingviews,copies,andmemory-mappedfiles.1)Viewsallowslicingwithoutcopying,directlymodifyingtheoriginalarray.2)Copiescanbecreatedwiththecopy()methodforpreservingdata.3)Memory-mappedfileshandlemassivedatasetsb

Which requires importing a module: lists or arrays?Which requires importing a module: lists or arrays?Apr 28, 2025 am 12:06 AM

ListsinPythondonotrequireimportingamodule,whilearraysfromthearraymoduledoneedanimport.1)Listsarebuilt-in,versatile,andcanholdmixeddatatypes.2)Arraysaremorememory-efficientfornumericdatabutlessflexible,requiringallelementstobeofthesametype.

What data types can be stored in a Python array?What data types can be stored in a Python array?Apr 27, 2025 am 12:11 AM

Pythonlistscanstoreanydatatype,arraymodulearraysstoreonetype,andNumPyarraysarefornumericalcomputations.1)Listsareversatilebutlessmemory-efficient.2)Arraymodulearraysarememory-efficientforhomogeneousdata.3)NumPyarraysareoptimizedforperformanceinscient

What happens if you try to store a value of the wrong data type in a Python array?What happens if you try to store a value of the wrong data type in a Python array?Apr 27, 2025 am 12:10 AM

WhenyouattempttostoreavalueofthewrongdatatypeinaPythonarray,you'llencounteraTypeError.Thisisduetothearraymodule'sstricttypeenforcement,whichrequiresallelementstobeofthesametypeasspecifiedbythetypecode.Forperformancereasons,arraysaremoreefficientthanl

Which is part of the Python standard library: lists or arrays?Which is part of the Python standard library: lists or arrays?Apr 27, 2025 am 12:03 AM

Pythonlistsarepartofthestandardlibrary,whilearraysarenot.Listsarebuilt-in,versatile,andusedforstoringcollections,whereasarraysareprovidedbythearraymoduleandlesscommonlyusedduetolimitedfunctionality.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

WebStorm Mac version

WebStorm Mac version

Useful JavaScript development tools

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft