module
Example 1: Import a specific function in a module
# 只导入time模块中的sleep方法，可以直接使用sleep调用不用加time.
from time import sleep
print("hello")
sleep(500)
print("fine")
# 只导入time模块中的sleep方法,并给sleep起别名为sl
from time import sleep as sl
print("hello")
sl(500) # ！！！
print("fine")
Example 2: Custom Module
When a custom module writes test code and imports the module in other code files, the test code will also be called, namely:
Note that the following are the codes of the two files
# my_moudle.py
def add(x, y):
print(f"{
x} + {
y} = {
x+y}")
add(8, 9)
# aa.py
import my_moudle
my_moudle.add(22, 12)
Execute aa.py output:
8 + 9 = 17
22 + 12 = 34
If you don't want to execute add(8, 9) in my_moudle.py, you can modify the code:
# my_moudle.py
def add(x, y):
print(f"{
x} + {
y} = {
x+y}")
if __name__ == '__main__':
add(8, 9)
__name__It is a built-in variable of each py file, only the running py file will be__main__
Example 3: __all__ global variable
# my_moudle.py
__all__ = ['add'] # 其他文件 以from my_moudle import * 导入，则只能用add函数
def add(x, y):
print(f"{
x} + {
y} = {
x+y}")
def sub(x, y):
print(f"{
x} - {
y} = {
x-y}")
python package
The python package is a folder , which contains modules, namely python files , and an additional one__init__.py
Create a python package method
Suppose there are two module files my_moudle1.py and my_moudle2.py under the folder
# my_moudle1.py
def print1():
print("模块1功能")
# my_moudle2.py
def print2():
print("模块2功能")
used in aa.py
# 这样导入，调用函数要写包名.模块名.方法名
import my_package.my_moudle1
import my_package.my_moudle2
my_package.my_moudle1.print1()
my_package.my_moudle2.print2()
# 这样导入，调用函数要写模块名.方法名
from my_package import my_moudle1
from my_package import my_moudle2
my_moudle1.print1()
my_moudle2.print2()
# 这样导入，调用函数只要写方法名
from my_package.my_moudle1 import print1
from my_package.my_moudle2 import print2
print1()
print2()
list sort method
That is, use your own defined comparison function to sort
my_list=[["a", 33], ["b", 55], ["c", 11]]
# 基于有名函数排序
# 表明按照element 的第二个元素进行排序
def choose_sort_key(element):
return element[1]
# reverse=True 表明是降序排列
#my_list.sort(key = choose_sort_key, reverse=True)
# 基于lambda匿名函数来降序排序
my_list.sort(key=lambda element:element[1], reverse=True)
print(my_list)
Output result:
[['b', 55], ['a', 33], ['c', 11]]