How to import and use modules and packages in Python?

In Python, modules and packages can be imported and used using the import keyword.

1. import module:

import module_name

This will import the specified module and allow access to the functions, classes, and other content defined in the module using module_name.

1. Import the module and specify an alias:

import module_name as alias_name

This will import the specified module and allow access to the content defined within the module using an alias_name.

1. Import specific content from a module.

from module_name import function_name, class_name

This will only import the functions, classes, etc. specified in the module, enabling you to use them directly without needing to prefix them with the module name.

1. Importing modules from a package:

from package_name import module_name

This will import the specified module from the package, which can be accessed through module_name to access the content defined in the package.

1. Import modules from the package and specify an alias:

from package_name import module_name as alias_name

This will import the specified module from the package, and the contents defined in the package can be accessed through alias_name.

1. Import all modules in the package.

from package_name import *

This will import all modules in the package, allowing access to all contents defined in the package.

Once you have imported a module or package, you can then use the functions, classes, variables, etc. that are defined within it. For example:

import math

print(math.sqrt(16))  # 计算平方根

I hope the above information is helpful to you. If you need further assistance with importing and using modules and packages in Python, please feel free to let me know.