Python3 functools partial 偏函数

本文主要是介绍Python3 functools partial 偏函数，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

今天我们要讲的偏函数，其实是函数的辅佐，什么意思呢，我们借助Python的help帮助函数，看一下

Shell

| <a href="https://www.168seo.cn/tag/partial" title="View all posts in partial" target="_blank">partial</a>(func, *args, **keywords) - new function with <a href="https://www.168seo.cn/tag/partial" title="View all posts in partial" target="_blank">partial</a> application | of the given arguments and keywords.

1 2	\| partial ( func , * args , * * keywords ) - new function with partial application \| of the given arguments and keywords .

Python

# -*- coding: utf-8 -*- """ @author:songhao @file: func.py @time: 2018/01/03 """ import <a href="https://www.168seo.cn/tag/functools" title="View all posts in functools" target="_blank">functools</a> # print(dir(<a href="https://www.168seo.cn/tag/functools" title="View all posts in functools" target="_blank">functools</a>)) from _operator import add fc = [x for x in dir(functools) if not x.startswith('_')] print(fc) # print(help(functools.partial)) def say(name, age): return (name, age) d = functools.partial(say, age=18) print(d('songhao')) print(d('songhao',age=28)) # /usr/local/bin/<a href="https://www.168seo.cn/tag/python" title="View all posts in python" target="_blank">python</a>3 "/Users/songhao/Desktop/<a href="http://www.168seo.cn/python" title="python">python</a> scrapy/func.py" # ['MappingProxyType', 'RLock', 'WRAPPER_ASSIGNMENTS', 'WRAPPER_UPDATES', 'WeakKeyDictionary', 'cmp_to_key', 'get_cache_token', 'lru_cache', 'namedtuple', 'partial', 'partialmethod', 'recursive_repr', 'reduce', 'singledispatch', 'total_ordering', 'update_wrapper', 'wraps'] # ('songhao', 18) # ('songhao', 28)

# -*- coding: utf-8 -*-

"""

@author:songhao

@file: func.py

@time: 2018/01/03

"""

import functools

# print(dir(functools))

from _operator import add

fc = [ x for x in dir ( functools ) if not x . startswith ( '_' ) ]

print ( fc )

# print(help(functools.partial))

def say ( name , age ) :

return ( name , age )

d = functools . partial ( say , age = 18 )

print ( d ( 'songhao' ) )

print ( d ( 'songhao' , age = 28 ) )

# /usr/local/bin/python3 "/Users/songhao/Desktop/python scrapy/func.py"

# ['MappingProxyType', 'RLock', 'WRAPPER_ASSIGNMENTS', 'WRAPPER_UPDATES', 'WeakKeyDictionary', 'cmp_to_key', 'get_cache_token', 'lru_cache', 'namedtuple', 'partial', 'partialmethod', 'recursive_repr', 'reduce', 'singledispatch', 'total_ordering', 'update_wrapper', 'wraps']

# ('songhao', 18)

# ('songhao', 28)

functools.partial的作用就是，把一个函数的某些参数给固定住（也就是设置默认值），返回一个新的函数，调用这个新函数会更简单。
冻结参数把多个函数的部分函数进行默认赋值