How to use the Python file system module pathlib library

1. Official definition of pathlib library

pathlib is a built-in library of Python. The definition given by the Python documentation is Object-oriented filesystem paths. pathlib provides classes representing file system paths, with semantics applicable to different operating systems.

The path classes are divided between pure paths, which provide pure computational operations without I/O, and concrete paths, which inherit pure paths but also provide I/O operations.

2. Pathlib cheats

1. Basic usage

• Path.iterdir() # Traverse the subdirectories of the directory or File

• Path.is_dir() # Determine whether it is a directory

• ##Path.

  glob () # Filter directory (return to generator)

##Path.
• resolve

  () # Return absolute path

Path .
• exists

  () # Determine whether the path exists

Path.
• open

  () # Open the file (supports with)

Path.
• unlink

  () # Delete a file or directory (the directory is not empty and triggers an exception)

2. Basic attributes

Path.
• parts

  # Splitting the path is similar to os.path.split(), but returns a tuple

Path.
• drive

  # Returns the drive name

Path.
• root

  # Returns the root directory of the path

Path.
• anchor

  # Automatically determine and return drive or root

Path.
• parents

  # Return a list of all parent directories

3. Change path

Path.
• with_name

  () # Change the path name, change the last level path name

Path.
• with_suffix

  () # Change path suffix

4, Splice path

Path.
• joinpath

  () #Join path

Path.
• relative_to

  () #Calculate relative path

  ##5 , Test path

Path.

match
• () # Test whether the path matches pattern
  Path.
is_dir
• () # Whether it is a file

  ##Path.

  is_absolute
() # Whether it is an absolute path

• Path .

  is_reserved
() # Whether it is a reserved path

• Path.

  exists
() # Determine whether the path actually exists

• 6. Other methods

Path.

cwd

() # Return the path object of the current directory

• Path.

  home
() # Return the current user’s home path object

• Path.

  stat
() # Return path information, Same as os.stat()

• Path.

  chmod
() # Change path permissions, similar to os.chmod()

• Path.

  expanduser
() # Expand~Return full path object

• Path.

  mkdir
() # Create directory

• Path.

  rename
() # Rename the path

• Path.

  rglob
() # Recursively traverse all Files in subdirectories

• 3. The difference between os and pathlib.Path

Compared with the path method of the os module, the Path of the Python3 standard library pathlib module operates on the path. It will be simpler.

1. Get the current file path

When using the os module, you can directly get the current file path through the

getcwd()

method

In Pycharm, You can use os.path.dirname(__file__) to get the current file path, because Python does not provide the concept of __file__, which is provided by Pycharm:

import os

print(os.getcwd())  # C:\Users\bobin.yang\PycharmProjects\untitled
print(os.path.dirname(__file__))  # C:/Users/bobin.yang/PycharmProjects/untitled

In the pathlib module, pass Path.cwd() method can directly obtain the current file path, we can give it a try:

import pathlib

print(pathlib.Path.cwd())  # C:\Users\bobin.yang\PycharmProjects\untitled

Through Pycharm we can use shortcut keys ctrl left mouse button Click to view a detailed introduction to this method.

As can be seen from the above picture, the cwd() method is just an encapsulation of the

getcwd()

method in the os library. It looks even worse. But the official launch is definitely not a fiction. Now let us reveal the secret together. 2. Get the upper/upper directory The above case seems to make the use of the pashlib library more complicated. In order to reveal the secret, we can only feel the composition of the pathlib library and understand pathlib How libraries bring us convenience.

In the os module, if we want to get the parent directory of a certain file, the os module is written as:

import os

print(os.path.dirname(os.path.dirname(os.getcwd())))  # C:\PycharmProjects

In the pathlib library, it can be achieved in this simple way:

import pathlib

print(pathlib.Path.cwd().parent)   # C:\PycharmProjects

And if you need to find his grandfather, just ask for another

.parent

. Compared with the os module's

os.path.dirname()

, is it too convenient? 3. Path splicingIf you want to splice the path in its parent directory, you may need to write such a long string of code through the os module:

import os

print(os.path.join(os.path.dirname(os.getcwd()), '路径拼接', '真麻烦'))  # C:\PycharmProjects\路径拼接\真麻烦

When you use pathlib, let’s experience its convenience together!

# /Users/mac/test.py
import os

paths = ('路径拼接', '真麻烦')
print(pathlib.Path.cwd().parent.joinpath(*paths))  # C:\PycharmProjects\路径拼接\真麻烦

通过 pathlib 库拼接路径，你可以很方便的调节他在他祖辈的位置，妙哉。

4、 其他封装

pathlib 封装了很多的 os.path 中的方法，如下所示：

• os.path.expanduser() --> pathlib.Path.home()

• os.path.expanduser() --> pathlib.Path.expanduser()

• os.stat() --> pathlib.Path.stat()

• os.chmod() --> pathlib.Path.chmod()

四、pathlib.PurePath的使用

上一节的操作大部分都是通过 pathlib 库中的 Path 实现，其实他还有一个更加高大上的模块，也就是我们这一节的主角：pathlib.PurePath。

PurePath 是一个纯路径对象，纯路径对象提供了实际上不访问文件系统的路径处理操作。

有三种方法可以访问这些类，我们也称之为 flavor 。

1、 PurePath.match

下面让我们来实现一个神奇的功能，判断当前的路径下是否有符合'*.py'规则的文件。

import pathlib

print(pathlib.PurePath(__file__).match('*.py'))  # True

输出为什么会是 True 呢？因为当前文件夹下不就有一个 test.py 吗？

2、 PurePath的子类：PurePosixPath（非Windows系统）、PureWindowsPath

看见 pathlib.PurePath 后面跟着 match，那是不是能说明他是个对象，而不是一个单纯的路径字符串，因此我们可以试着打印 pathlib.PurePath 看一看。

import pathlib

os_path = os.path.dirname(__file__)
print(os_path)  # C:/PycharmProjects/untitled

pure_path = pathlib.PurePath(__file__)
print(pure_path)  # C:\PycharmProjects\untitled\run.py
print(type(pure_path))  # <class &#39;pathlib.PureWindowsPath&#39;>


print(pathlib.PurePath(__file__).match(&#39;*.py&#39;))  # True

通过打印 os.path 获取当前路径的结果，得到一个路径字符串；而通过 pathlib.PurePath 则获得了一个 PurePosixPath 对象，并且由此得到的路径包括了当前文件 run.py。

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