Summary of how to quickly traverse all files in folders using Python

1. Why do you need to traverse all files in a folder?

In many practical application scenarios, we need to operate on all files in the folder. Here are some common examples:

File processing and conversion: For example, converting a batch of image files from one format to another, or performing content analysis and processing of large numbers of text files.
Data collection and sorting: When it is necessary to collect data from multiple files and organize and analyze it, traversing all files in the folder can help us quickly find the data we need.
Automation tasks: For example, regularly backup important files in folders, or automatically classify and archive specific types of files.
Program debugging and error handling: When debugging a program, you may need to check all files under a specific folder to determine whether there are errors or exceptions.

2. Methods to traverse folders in Python

Python provides multiple ways to iterate through all files in a folder. Below we will introduce several commonly used methods and compare their advantages and disadvantages.

1. Use the os module

osModules are standard library modules in Python for interaction with operating systems. It provides many functions and methods for handling file and directory operations. The following is usedosBasic methods for modules to traverse folders:

import os

def traverse_folder(folder_path):
    for root, dirs, files in (folder_path):
        for file in files:
            file_path = (root, file)
            print(file_path)

traverse_folder('/path/to/folder')

In the above code, we use()The function traverses all files under the specified folder and its subfolders.()The function returns a triple(root, dirs, files),inrootIndicates the directory path currently traversed,dirsis a list of subdirectories in the current directory.filesIt is the file list in the current directory. We can loop throughfilesList, get the path to each file, and perform corresponding processing.

advantage：

Simple and easy to use, it is the most basic method of traversing folders in Python.
You can traverse files under a specified folder and all of its subfolders.

shortcoming：

For large folders, the traversal speed may be slow.
The depth and order of traversal cannot be directly controlled.

2. Use the glob module

globModules are modules in Python for file path matching. It provides an easy way to find file paths that match a specific pattern. The following is usedglobHow to traverse folders for modules:

import glob

def traverse_folder(folder_path):
    for file_path in (folder_path + '/**/*', recursive=True):
        print(file_path)

traverse_folder('/path/to/folder')

In the above code, we use()Functions find all files under the specified folder and its subfolders.()The function takes a file path pattern as an argument and returns a list of matching file paths. We can use wildcards*to represent any character, use**to represent a subdirectory of any depth. By settingrecursive=TrueParameters, we can recursively look up files under subfolders.

advantage：

It is possible to use wildcard characters for file path matching, which is very flexible.
For a specific file path mode, the traversal speed may be higher than()Faster.

shortcoming：

Can't be like()In this way, you can directly obtain the subdirectory list in the current directory.
For complex folder structures, multiple wildcards may be required to match, and the code may become more complex.

3. Use the pathlib module

pathlibModules are new in Python 3.4 and above, which provides an object-oriented way to handle file and directory paths. The following is usedpathlibHow to traverse folders for modules:

from pathlib import Path

def traverse_folder(folder_path):
    folder = Path(folder_path)
    for file_path in ('*'):
        print(file_path)

traverse_folder('/path/to/folder')

In the above code, we usePathClasses represent file and directory paths. By calling('*')Method, we can recursively find all files under the specified folder and its subfolders.rglob()The method takes a file path pattern as a parameter and returns a generator object. We can use a loop to traverse the generator object and get the path to each file.

advantage：

Provides an object-oriented way to handle file and directory paths, and the code is more concise and easy to read.
It can conveniently perform files and directories operations, such as creation, deletion, movement, etc.

shortcoming：

Incompatible with Python 3.4 or below.
In some cases, the traversal speed may be lower than()andglobModule.

3. Performance optimization of traversal folders

The performance of traversing folders can become a problem when dealing with large amounts of files. Here are some ways to optimize the performance of a folder:

1. Avoid repeated traversals

When traversing folders, try to avoid repeatedly traversing the same files and directories. You can use a collection or dictionary to record the paths of files and directories that have been traversed so that they can be skipped in subsequent traversals.

import os

visited = set()

def traverse_folder(folder_path):
    for root, dirs, files in (folder_path):
        for file in files:
            file_path = (root, file)
            if file_path not in visited:
                (file_path)
                print(file_path)

traverse_folder('/path/to/folder')

In the above code, we use a collectionvisitedTo record the file path that has been traversed. When iterating through each file, we check if the file path is already in the collection, and if not in the collection, print the file path and add it to the collection. This avoids repeated traversal of the same file.

2. Parallel traversal

If your computer has multiple CPU cores, consider using parallel programming techniques to speed up the process of traversing folders. In PythonmultiprocessingandThe module provides a convenient parallel programming interface.

import os
import multiprocessing

def process_file(file_path):
    # Code for processing files    print(file_path)

def traverse_folder(folder_path):
    pool = ()
    for root, dirs, files in (folder_path):
        for file in files:
            file_path = (root, file)
            pool.apply_async(process_file, args=(file_path,))
    ()
    ()

traverse_folder('/path/to/folder')

In the above code, we define aprocess_file()Function, used to process a single file. When iterating through the folder, we use()Create a process pool and submit the processing tasks of each file to a process in the process pool for execution. This allows you to make full use of multiple CPU cores of your computer and improve the speed of traversing folders.

3. Reduce unnecessary file operations

When traversing folders, try to minimize unnecessary file operations, such as opening, reading, writing files, etc. If you only need to obtain the path information of the file, you can directly use the file path to process it without opening the file.

import os

def traverse_folder(folder_path):
    for root, dirs, files in (folder_path):
        for file in files:
            file_path = (root, file)
            # Use the file path directly to process without opening the file            print(file_path)

traverse_folder('/path/to/folder')

In the above code, we only print the path information of the file without performing any file operations. This can reduce unnecessary file operations and improve the speed of traversing folders.

4. Things to note when traversing folders

When traversing folders, you need to pay attention to the following points:

Permissions issues: Make sure your program has sufficient permissions to access specified folders and files. If you encounter insufficient permissions, you can try running the program as an administrator, or adjusting the permission settings for folders and files.
File Type Filtering: If you only need to traverse a specific type of file, you can filter the file type during the traversal. For example, you can use a file extension to determine the file type and only process files that meet the criteria.
Exception handling: When traversing the folder, you may encounter various abnormal situations, such as the file does not exist, insufficient permissions, and file corruption. In order to ensure the stability of the program, appropriate exception handling should be carried out during the traversal process.
Recursive depth limit: If the folder structure is very deep, it may cause the recursive depth to exceed Python's default limit. In this case, consider using a non-recursive approach to iterating over folders, or adjusting Python's recursive depth limit.

5. Summary

This article describes how to use Python to quickly traverse all files in a folder. We have introduced three commonly used methods to traverse folders, including usingosModule,globModules andpathlibmodules and compare their pros and cons. We also introduce some methods to optimize the performance of traversal folders, such as avoiding repeated traversals, parallel traversals, and reducing unnecessary file operations. Finally, we reminded some issues that need to be paid attention to when traversing folders, such as permission issues, file type filtering, exception handling, and recursive depth limitations. Hope this article will be helpful to you when using Python for file operations.

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