# A module is the highest-level organizational unit in Python. It packages program code and data for reuse, and contains multiple functions and attributes to implement a certain type of business. # A module is a toolkit to implement a certain type of business . To use the tools in the toolkit (usually functions), you need to import this module. Modules are also called packages or libraries. #How to import modules? # import module name is essentially introducing another python file into a python file # The introduced module can also set an alias in the document: import module name as alias # Introduce part of a complex module from module name import submodule # 1. Built-in module random import random r=random.randint(1,6)#randint means randomly generating an integer between 1 and 6 print(r) r1=random.uniform(1,6)#means 1 to 6 Randomly generate a decimal print(r1) r3=random.choice([1,132,32,43,43,454,46,56,55,76,7]) #Randomly obtain a value in a sequence r4=random.random () #Generate 0-1 random floating point number #2. Built-in module time import time #Countdown i=10 while i>=0: print("Countdown:",i) time.sleep(1) i-=1 #3. Built-in module datetime import datetime #Get the current date and time now=datetime.datetime.now() print(now) #Get a specified time d1=datetime.datetime(2018,2,13,5,23,45) print(d1) #Convert date to string s1=d1.strftime("%Y year-%m month-%d day %H:%M:%S") print(s1) #Convert string to date (the format must be Consistent) s2="2018/02/13 05:23:45" d2=datetime.datetime.strptime(s2,"%Y/%m/%d %H:%M:%S") print(d2,type (d2)) #Return as follows: 2022-06-28 11:22:48.655992 2018-02-13 05:23:45 2018-02-13 05:23:45 2018-02-13 05:23: 45 <class 'datetime.datetime'> 4. Built-in module urllib from urllib import request url="http://www.baidu.com" data=request.urlopen(url).read() #Send the request and read the data print(data.decode()) #decode() decoding: convert binary into characters with open(r"0413.html","wb") as f: f.write(data)#Write the content in the Baidu link In 0413, #python modules are placed in the lib folder: C:\Users\username\AppData\Local\Programs\Python\Python310\Lib #Introduce the python file you wrote import supermarket system #If you introduce it directly like this , the default programs in the module will be executed.
When introducing a module, the default code is also executed. At this time, the imported module must be transformed and the default executed statement is placed in the main function. def main():
Default
executed function module
if __name__== '__main__':
main()
#This statement means: the main function will only be executed when the python file of the module itself is executed. The main function will not be executed when the module is referenced by the outside world. Modules are divided into
: built-in modules: such as random, and Third-party modules: need to be downloaded before they can be introduced
Python third-party package installation method
Method 1 (using pip, you need to upgrade before using it for the first time):
Open cmd directly and enter the command.
pip tool upgrade: python -m pip install --upgrade pip
Install module: pip install module name
Uninstall the module: pip uninstall module name
View installed third-party packages: pip list
Display module information: pip show module name
pip installation can specify the version: pip install django==3.1.5
Method 2 (Tsinghua Mirror):
pip install -i https://pypi.tuna.tsinghua.edu.cn/simple module name
Method 3 (online download):
Step1: Find the required package https://pypi.python.org online and download it.
Step2:
Whl installation method: cmd enter the directory where the whl file is located, execute pip install file name
Folder installation method (setup): cmd enter the directory of the installed package, find the setup.py file, and then enter python setup.py install
(You can also use this method to install pip when you don’t have the pip tool)
The 4th method (download from pycharm):
【File】→【Settings】→【Project】→【Project Interpreter】