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This article is to share with you about the way Python modules are imported. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

Concept

The Python module is a Python file that ends in .py and contains Python object definitions and Python statements. Each module is treated as a separate file in python. The module can be introduced by other programs to use functions and other functions in the module, which is also the way to use the python standard library.

Module import

Modules can import other modules, and it is customary to place all import statements at the beginning of the module (not required). There are several ways to import modules:

Method 1: use import statements to introduce modules

Import module1 [, module2 [,... ModuleN]] # for example, import a path module import path

Directly use the keyword import, followed by a specific module name, you can import a module. No matter how many times the import is executed, the same module will only be imported once to prevent the module from being executed over and over again.

After the module is introduced, if you want to call the functions in the module, you must be as follows:

Module name. Function name

Method 2: use from … Import statement to introduce the module

From modname import name1 [, name2 [,... NameN]] # for example, the pprintfrom pprint import pprint to import the pprint module

When you import a module using the import statement, the entire module is introduced, while using from... The import statement imports a specified part from the module into the current namespace. As in the above code, only the pprint function in the pprint module will be imported, and other functions will not be imported.

After the import statement is introduced into the module, if you need to use the function method in the module, you need to add the qualified name of the module, while the from...import statement directly uses its function method without adding the qualified name of the module.

# the first method import pprintpprint.pprint ("hello world") # the second method from pprint import pprintpprint ("hello world")

Method 3: use from … Import* statement to introduce the module

From... The import* statement means to import all the contents of a module into the current namespace.

From modname import *

In most cases, Python programmers will not use this feature because it introduces an unknown set of names into the interpreter, and they are likely to overwrite something you have already defined.

Note that it is generally not acceptable to call * from a module or package because it usually results in poor readability of the code. However, this can be used in interactive compilers to save typing.

Module search path

The search path consists of a series of directory names from which the Python interpreter looks for the introduced modules. When a module is imported, the search path for the module is:

The root directory of the program

The directory set by the PYTHONPATH environment variable

Directory of the standard library

The contents of any file .pth that can be found

Third-party extended site-package directory

PYTHONPATH variable

PYTHONPATH is an important environment variable in Python, which is used to search the path when the module is imported. It can be accessed in the following ways:

Import syssys.path

As an environment variable, PYTHONPATH consists of many directories in a list. The syntax of PYTHONPATH is the same as that of the shell variable PATH.

On Windows systems, a typical PYTHONPATH is as follows:

Set PYTHONPATH=c:\ python37\ lib; Thank you for reading! This is the end of this article on "what are the ways to import Python modules?". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it out for more people to see!

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