Python Pathlib 模块

2024 年 8 月 29 日 | 14 分钟阅读

出于各种原因，与文件系统进行交互和处理文件至关重要。最简单的情况可能只是读取或写入文件，但有时也需要更复杂的操作。也许您需要显示某个特定类型的所有文件，查找文件的父目录，或者生成一个不存在的新文件名。

任何 Python 脚本都离不开文件系统。它可能像将数据文件读入 pandas DataFrame 一样简单，也可能像处理高度嵌套目录结构中的数百个文件一样复杂。为了实现这些目的，Python 的标准库提供了许多有用的方法，特别是 pathlib 模块。

Pathlib 模块最初出现在 Python 3.4 中，并在后续的每个版本中都得到了改进。Pathlib 是一个面向对象的 **文件系统接口**，它提供了一种更自然、与平台无关且更 Pythonic 的方式来与文件系统进行交互。我最近完成了一个简短的项目，在这个项目中，我选择使用 pathlib 和 pandas 来处理嵌套目录结构中数千个文件的排序和管理。这个项目启发了我写这篇文章。当我完成这一切时，我被 pathlib 的功能所震惊，我将来毫不犹豫地在项目中使用它。所有大于或等于 3.4 的 Python 版本都包含 pathlib 库。为了获得所有最新的升级，我建议使用最新版本的 Python。在这篇文章中，我将使用 Python 3.6。

Pathlib 模块的一个优点是，无需使用 os.joindir 即可轻松创建路径。例如，当我开始小型项目时，我使用 os.getcwd() 在当前工作目录下方创建输入和输出子目录。我将工作输入和输出文件保存在这些位置。代码可能如下所示：

语法

import os

in_dir = os.path.join(os.getcwd(), "in")
out_dir = os.path.join(os.getcwd(), "out")
in_file = os.path.join(in_dir, "input.xlsx")
out_file = os.path.join(out_dir, "output.xlsx")

传统上，Python 一直使用普通文本字符串来表示文件路径。借助 os.path 标准库（如引言中的第二个示例所示），这已经足够了，尽管有些繁琐。然而，由于路径不是字符串，关键功能分散在标准库中，包括 os、glob 和 shutil 等库。为了将所有文本文件移动到存档目录，以下示例需要三个导入语句：

语法

import glob
import os
import shutil

for file_name in glob.glob('*.txt'):
    new_path = os.path.join('archive', file_name)
    shutil.move(file_name, new_path)

使用字符串表示的路径，用标准字符串方法是可能的，但通常是一个糟糕的主意。您应该使用 os.path.join() 来连接两个路径，而不是像使用常规字符串那样使用 +，它使用操作系统正确的路径分隔符来连接路径。请记住，在 Windows 上，分隔符是 /，而在 Mac 和 Linux 上，分隔符是 /。这个区别可能会导致难以检测的问题，就像引言中的第一个示例一样，它只适用于 Windows 路径。

为了解决这些问题，Pathlib 模块在 Python 3.4 (PEP 428) 中被添加。它将所有必需的功能集中在一个地方，并通过简单的 Path 对象的方法和属性来访问。其他包最初使用字符串作为文件路径，但自 Python 3.6 以来，得益于文件系统路径协议的创建，pathlib 模块已在整个标准库中得到支持。如果您还在使用旧版 Python，也可以获取 Python 2 的向后移植版本。

代码

#Sample python code for the usage of pathlib module provided by the python

# importing the required libraries  that are used across the  program
import pathlib
import sys

# a class is written which will have different functions to perform or simulate the different functionalities of the pathlib  library provided by the python 
class FunctionalitiesOfPathlib:
	
	#Constructor is written that will be just a placeholder in case of any further actions to be taken before the object initialisation of this class
	def __init__(self):
		pass
	# this function is used to list all the subdirectories that are present in a directory this function prints all the directories that are present in the directory which is passed as a parameter to this function the part of the directory which is passed as a parameter to this function is used as a parent directory and the directory is inside the parent directory are treated as  children directories
	def list_all_subdirectories_in_a_directory(self,path_of_main_directory):
		 path_object = pathlib.Path(path_of_main_directory)
		 for item in path_object.iterdir():
		 	if item.is_dir():
		 		print(item)

	# this function is used to list all the files that are present in a particular directory to list all the files that are present in a directory this function is called with the parameter as the directory whose files we want to list the point to be noted here that it this function only list the files inside the parent directory and will not list the subdirectories for the children directories present inside the parent directory
	def list_all_files_in_a_directory(self,path_of_main_directory):
		path_object = pathlib.Path(path_of_main_directory)
		for item in path_object.iterdir():
			if not item.is_dir():
				print(item)

	# a function is written that will be used to check whether a file is present at a particular location or not the return type of this function is of the Boolean type which means the returning value of this function is determined by the presence of the file at that particular location or not if the file specified is present at the specified location then the return type of this function is true on the other hand if the specified file is not present in the particular directory the return type of this function will be changed to false type and the similar message is printed according 
	def check_file_present(self,path_to_file):
		path_object = pathlib.Path(path_to_file)
		if path_object.is_file():
			print("File is present.")
			return True
		else:
			print("File is not present.")
			return False
	# a function is written to get the current working directory of the code execution whenever the user selects the execution of this function returns and prints the current working directory where the code is getting executed point to be noted here is that if the user has performed  the change directory operation then the latest directory will be created as the current working directory of the program execution and the same will be printed and displays as the current working directory of the code
	def get_current_working_directory(self):
		code_cwd = pathlib.Path().cwd()
		print("The current working directory is: {}".format(code_cwd))
	
	# this function is used to change the current working directory of the code execution let's say if the code is executed in directory 1 And we want to change the current working directory to directory 2  so we can use this function that will change the current working directory to the new directory whose path is specified as a parameter to this function show the absolute path which is passed as a parameter to this function will be treated as the next current working directory and the return type of this function is of the Boolean type that means the returning value of this function is determined by the success or failure of the change current working directory operation if the current working directory is changed successfully then the return type is true and whereas on the other hand if Changing of the current working directory is field due to some reasons that the return type of this function will be changed to false
	def change_current_working_directory(self,path_to_new_directory):
		code_cwd = pathlib.Path().cwd()
		path_object = pathlib.Path(path_to_new_directory)
		return_code = path_object.cd()
		if return_code:
			print("The Current working directory changed successfully from {} to {}".format(code_cwd,path_to_new_directory))
			return True
		else:
			print("Unable to change the current working directory.")
			return False


# and in the end the main function is written that will provide a menu-driven approach to the user to call all the above-written functions  showing different functionalities of the pathlib module in Python  and the end this main function is called to execute our code
def main():

	# 
	while(True):
		print("Please choose one of the appropriate options::")
		print("1. To print all the sub-directories of a folder/dir.")
		print("2. To print all the files present inside a folder/directory.")
		print("3. Check the existence of a specified file")
		print("4. To check the current directory of the code execution.")
		print("5. To modify the current directory of the code execution. (using the chdir() function)")
		print("6. To exit from the code execution.")
		menu_choice = input()
		menu_choice = int(menu_choice)

		pathlib_object = FunctionalitiesOfPathlib()

		# if the user chooses the first option then the user is asked for the absolute path of the directory whose subdirectories he wants to list after entering the absolute path all the subdirectories present in the entered directory are listed one by one
		if menu_choice == 1:
			print(">Enter the absolute path of the directory whose sub-directories you want to list::")
			input_str = input()
			pathlib_object.list_all_subdirectories_in_a_directory(input_str)

		# on selecting the second option the user is again asked for the absolute path of the directory whose files the user wants to list after adding  the path of the directory all the files present in that directory are listed
		elif menu_choice == 2:
			print(">Enter the absolute path of the directory whose files you want to list::")
			input_str = input()
			pathlib_object.list_all_files_in_a_directory(input_str)
			
		#  selecting option 3 the user have to add the path of the file whose existence  the user wants to check if the file is present at the specified location the user is prompted with the successful message on the other hand if the file is not present the user is prompted with the unsuccessful message
		elif menu_choice == 3:
			print(">Enter the absolute path of the file which you want to check is present::")
			input_str = input()
			pathlib_object.check_file_present(input_str)

		# on selecting the  fourth option the current working directory of the code is printed
		elif menu_choice == 4:
			pathlib_object.get_current_working_directory()
		
		# on selecting the fifth option of the above show me menu the user is asked for the absolute path to the new directory to which the user wants to change and then that directory will be treated as the current working directory of the code execution on the successful change of the current working directory to the new specified directory a successful message is prompted to the user whereas on the other hand if the change of current working directory is unsuccessful due to any reason the same message will be prompted to the user indicating him about the unsuccessful change of directory 
		elif menu_choice == 5:
			print(">Enter the absolute path to the new directory to which you want to change::")
			input_str = input()
			pathlib_object.change_current_working_directory(input_str)
		
		print("Do you want to continue or exit the code execution?[y/n]")
		continue_or_exit = input()


		#After the completion of one round a question is prompted to the user asking whether you want to continue the code execution or you want to exit the code depending upon the input provided by the user further actions are taken if the user wants to continue the code execution and perform further operations related to dir and listing of the dir, the code is continued whereas on the other hand if the user wants to exit the code execution the exit function is called and the program is ended
		if continue_or_exit == 'y' or continue_or_exit == 'Y':
			pass
		elif continue_or_exit == 'n' or continue_or_exit == 'N':
			sys.exit()


if __name__ == '__main__':
	main()

输出

root@superbook:/# python3 /home/nirnay/code.py
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
1
>Enter the absolute path of the directory whose sub-directories you want to list::
/directory1
/directory1/directory4
/directory1/directory3
/directory1/directory2
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
2
>Enter the absolute path of the directory whose files you want to list::
/directory1
/directory1/java_code.java
/directory1/c++_code.c++
/directory1/python_code.py
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
3
>Enter the absolute path of the file which you want to check is present::
/directory1/python_code.py
The file is present.
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
4
The current working directory is: /
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
5
>Enter the absolute path to the new directory to which you want to change::
/directory1
The Current working directory changed successfully from / to /directory1
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
4
The current working directory is: /directory1
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
1
>Enter the absolute path of the directory whose sub-directories you want to list::
/directory1
/directory1/directory4
/directory1/directory3
/directory1/directory2
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
5
>Enter the absolute path to the new directory to which you want to change::
/directory1/directory2
The Current working directory changed successfully from /directory1 to /directory1/directory2
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
4
The current working directory is: /directory1/directory2
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
2
>Enter the absolute path of the directory whose files you want to list::
/directory1/directory2
/directory1/directory2/files6
/directory1/directory2/files1
/directory1/directory2/files3
/directory1/directory2/files4
/directory1/directory2/files2
/directory1/directory2/files5
/directory1/directory2/files8
/directory1/directory2/files10
/directory1/directory2/files7
/directory1/directory2/files9
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
5
>Enter the absolute path to the new directory to which you want to change::
/directory1/directory4
The Current working directory changed successfully from /directory1/directory2 to /directory1/directory4
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
5
>Enter the absolute path to the new directory to which you want to change::
/directory1/directory3
The Current working directory changed successfully from /directory1/directory4 to /directory1/directory3
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To print all the sub-directories of a folder/dir.
2. To print all the files present inside a folder/directory.
3. Check the existence of a specified file
4. To check the current directory of the code execution.
5. To modify the current directory of the code execution. (using the chdir() function)
6. To exit from the code execution.
4
The current working directory is: /directory1/directory3
Do you want to continue or exit the code execution?[y/n]
n
root@superbook:/# tree directory1

directory1/
├── c++_code.c++
├── directory2
│ ├── files1
│ ├── files10
│ ├── files2
│ ├── files3
│ ├── files4
│ ├── files5
│ ├── files6
│ ├── files7
│ ├── files8
│ └── files9
├── directory3
│ ├── files11
│ ├── files12
│ ├── files13
│ ├── files14
│ ├── files15
│ ├── files16
│ ├── files17
│ ├── files18
│ ├── files19
│ └── files20
├── directory4
│ ├── files21
│ ├── files22
│ ├── files23
│ ├── files24
│ ├── files25
│ ├── files26
│ ├── files27
│ ├── files28
│ ├── files29
│ └── files30
├── java_code.java
└── python_code.py

说明

在查看上述代码的输出之前，目录结构显示父目录名为 directory 1，其下有三个子目录，分别名为 directory 2、directory 3 和 directory 4。每个子目录中都存在 10 个文件，而在父目录中，除了这三个子目录之外，还有三个文件。

现在让我们看看上述代码的输出，在执行上述程序后，用户会看到 6 个选项：第一个选项是列出父目录下的所有子目录；第二个选项是列出特定目录下的所有文件；选项 3 是检查特定文件是否在特定位置存在；选项 4 是打印代码执行的当前工作目录；选项 5 是将代码执行的当前工作目录更改为指定为该功能方法参数的新目录。最后是第 6 个选项，用于执行代码。

结论

因此，在本文中，我们了解了 Python 的 pathlib 模块，并看到了可以利用 pathlib 模块提供的各种功能的各种用例场景。

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