python基础

Posted 2020-11-22 anyux

目录

• 匿名函数
• 正则表达式
  • match提取内容
• 模块的导入导出
  • 查找模块顺序
  • 导入方法及别名
• 装饰器
  • 简单装饰器
  • 装饰器语法糖
  • 初级装饰器传参

匿名函数

匿名是因为不需要以标准的方式来声明，如使用def语句
lambda [arg1,[ar2,...argN]:expression

#定义匿名函数
In [1]: a = lambda x,y: x+y

In [2]: ?a
Signature: a(x, y)
Docstring: <no docstring>
File:      ~/<ipython-input-1-07b4826b0230>
Type:      function

#直接返回结果
In [3]: a(2,4)
Out[3]: 6

正则表达式

search()方法，搜索123，只要"abc123milk"中存在，就返回结果
match()方法，默认是从开头查找，

In [4]: import re

In [5]: re.search("123","abc123milk")
Out[5]: <_sre.SRE_Match object; span=(3, 6), match='123'>

In [6]: re.search("123","abc1c3milk")

In [7]: re.search("1.3","abc1c3milk")
Out[7]: <_sre.SRE_Match object; span=(3, 6), match='1c3'>

In [8]: re.match("1.3","abc1c3milk")

In [9]: re.match("[0-9]{3}1.3","abc1c3milk")

In [10]: re.match("[a-w]{3}1.3","abc1c3milk")
Out[10]: <_sre.SRE_Match object; span=(0, 6), match='abc1c3'>

match提取内容

提取内容：使用小括号将内容括起来, [a-w]{3}(1.3)取出内容
groups()取得结果，得到无组

In [11]: re.match("[a-w]{3}(1.3)","abc1c3milk").groups()
Out[11]: ('1c3',)

group(0)取出整个正则匹配到的结果
group(1)取出想要取出第一个小括号中的结果
group(2)取出想要取出第二个小括号中的结果

In [12]: re.match("[a-w]{3}(1.3)","abc1c3milk").group(0)
Out[12]: 'abc1c3'

In [13]: re.match("[a-w]{3}(1.3)","abc1c3milk").group(1)
Out[13]: '1c3'

In [17]: re.match("[a-w]{3}(1.3)([a-z]{4})","abc1c3milk").group(2)
Out[17]: 'milk'

模块的导入导出

import module from module import name [,name2,nam3,...nameN] import as

查找模块顺序

In [18]: import sys

In [19]: sys.path
Out[19]: 
['',
 '/usr/lib64/python36.zip',
 '/usr/lib64/python3.6',
 '/usr/lib64/python3.6/lib-dynload',
 '/usr/local/lib64/python3.6/site-packages',
 '/usr/local/lib/python3.6/site-packages',
 '/usr/lib64/python3.6/site-packages',
 '/usr/lib/python3.6/site-packages',
 '/usr/local/lib/python3.6/site-packages/IPython/extensions',
 '/root/.ipython']

‘‘,代表先查找当前目录，然后向下查找

导入方法及别名

In [20]: from re import search

In [21]: from re import search as sss

In [22]: sss("abc","123abcmilk")
Out[22]: <_sre.SRE_Match object; span=(3, 6), match='abc'>

装饰器

装饰器本质上是一个Python函数
装饰器的返回值也是一个函数对象
它可以让其他函数在不需要做任何代码变动的前提下增加额外功能

简单装饰器

def debug(func):
    def wrapper():
        print("[DEBUG]: enter {}()".format(func.__name__))
        return func()
    return wrapper

def say_hello():
    print("hello!")

say_hello = debug(say_hello)  # 添加功能并保持原函数名不变

装饰器语法糖

def debug(func):
    def wrapper():
        print("[DEBUG]: enter {}()".format(func.__name__))
        return func()
    return wrapper

@debug
def say_hello():
    print("hello!")

初级装饰器传参

def debug(func):
    def wrapper(*args, **kwargs):  # 指定宇宙无敌参数
        print("[DEBUG]: enter {}()".format(func.__name__))
        print('Prepare and say...',)
        return func(*args, **kwargs)
    return wrapper  # 返回

@debug
def say(something):
    print("hello {}!".format(something))